Maine Birds

2010-02-21T13:39:00.000-05:00

New address

Hello,

I have moved the Maine Birds blog to a new site. Please come visit at http://web.colby.edu/mainebirds/

Herb Wilson

2010-02-13T11:29:00.000-05:00

For the Birds - Maine Christmas Bird Count Highlights II

This column is the second in a series of three documenting the highlights of Christmas Bird Counts in Maine, held between mid-December and early January. Let’s take a trip along the coast of Maine, visiting six Christmas Count circles.

The Biddeford count tallied a fine total of 82 species on January 5. Snow Geese in Maine during the winter are unusual, so the two found here were good finds. Twelve other, more expected species of waterfowl were found.

Red-throated Loons are usually much less common than Common Loons during the winter in Maine; 13 and 146 of these species, respectively, fit this pattern. Red-necked Grebes (93) were outnumbered by Horned Grebes (176).

The 377 Purple Sandpipers were joined by a lone Dunlin for the only shorebirds found this year. Regularly occurring Black Guillemots along with the more unusual 14 Razorbills and two Thick-billed Murres made for a nice trio of alcids.

Some migratory breeding birds or migrants linger in Maine into the winter. Such birds included a Great Blue Hero, a Northern Flicker, a Gray Catbird, a Field Sparrow, three Savannah Sparrows and a Lincoln’s Sparrow. The total of 675 American Robins was impressive.

Four finch species were found with the nine Purple Finches and nine Pine Siskins being the most notable. These two species are tough to find this winter in Maine so far.

The count held in the Pemaquid/Damariscotta area produced a list of 69 species. This area usually has abundant Common Eiders so the 1,421 found this year were expected. Not expected were a King Eider and a Ring-necked Duck.

This area is also a good place to look for foraging Northern Gannets just offshore; 87 were counted this year.

A Turkey Vulture was an exceptional find this year; most have migrated from Maine by the end of October.

The rocky shores in this area are great for Purple Sandpipers and 223 were present this year. Less expected were the dozen Ruddy Turnstones.

Three species of alcids were found with three Dovekies and a singleton Razorbill joining the 22 Black Guillemots.

Three Belted Kingfishers either found open freshwater or fished in the ocean for their food. Lingering landbirds included an extraordinary nine Chipping Sparrows, a Fox Sparrow, a White-crowned Sparrow and two Common Grackles.

The Thomaston/Rockland count produced 72 species. The 15 species of waterfowl included a Snow Goose, an impressive 541 Buffleheads and three Ruddy Ducks. A Pacific Loon was an excellent find.

Six species of raptors were found including a couple of Rough-legged Hawk and an impressive total of 20 Red-tailed Hawks.

Four Bonaparte’s Gulls and a single Black-legged Kittiwake were present along with much more numerous and common Herring Gulls, Ring-billed Gulls and Great Black-backed Gulls.

Lingering birds included four Northern Flickers, a Belted Kingfisher, a Ruby-crowned Kinglet, and a Swamp Sparrow,

The North Penobscot Bay count, including the town of Belfast, yielded 50 species. Waterfowl diversity was good with 12 species recorded. American Black Ducks (206) outnumbered Mallards (140). This region is reliable for Barrow’s Goldeneye. One was tallied this year along with 173 Common Goldeneyes.

Loon and grebe abundance was low with only five Common Loons and a single Horned Grebe found.

A Red-bellied Woodpecker was a nice find; this species continues to make inroads into Maine. A Carolina Wren was unexpected. This species is sometimes described as “half-hardy”; they can tolerate a moderate New England winter but not a severe one.

As I noted in the last column, this winter does not seem to be particularly promising for invasions by Pine Siskins, Common Redpolls and other northern finches. But in the Belfast area, Pine Siskins (26) and Common Redpolls (25) nearly outnumbered the 35 House Finches.

Further downeast, the Schoodic Point count yielded 62 species. A Northern Pintail was the most unusual of 12 species of waterfowl. The 244 Red-necked Grebes were particularly abundant this year.

Less common gulls included two Bonaparte’s Gulls, a Glaucous Gull and 14 Black-legged Kittiwakes.

Most of the landbirds found this year were either residents or regular wintering species. The few lingering birds were two Belted Kingfishers, a Northern Flicker and five Common Grackles.

I’ll end with the northernmost count in Maine, the Presque Isle count. Participants found 29 species, about the average number of species on this count. The 180 Common Ravens outnumbered the 54 American Crows. Two Gray Jays were good additions.

Bohemian Waxwings had invaded with 412 counted. This area has lots of open fields, providing habitat for 2,342 Snow Buntings. The only finches were 39 Purple Finches and 14 Pine Siskins.

[Originally published on January 24, 2010]

2010-02-13T11:27:00.000-05:00

For the Birds - Maine Christmas Bird Count Highlights I

Christmas Count season is upon us. Organized by the National Audubon Society, this census effort has given us a valuable snapshot of early winter bird distribution for over the past 100 years. Over 20 counts are held in Maine. This column is the first in a series describing the highlights of the 2009/2010 counts.

Each winter, bird abundance in Maine is increased by varying numbers of irruptive (meaning moving into) birds from our north. Such species include Common Redpolls, Pine Grosbeaks and other northern finches as well as Bohemian Waxwings. In some years, Snowy Owls, Great Gray Owls and Northern Hawk Owls grace us with their presence for the winter. Alas, this year is a poor one so far for these erratic winter visitors.

Maine’s southernmost count, the York count, was held on December 14 and produced a fine list of 86 species. With lots of coastal and freshwater habitat, this count circle usually produces a nice diversity of waterfowl. This year’s count was no exception with 16 species found. The most notable waterfowl were three Snow Geese and two Gadwall. Harlequin Ducks in eastern North America seem to be declining so the 86 individuals of these handsome birds on the York count were nice to see.

The combination of the southerly location of this count and early date for this count in the nearly three-week counting period resulted in a number of birds that were lingering later than normal for this species. I am sure most of these birds have found their way farther south now!

These lingerers included Double-crested Cormorant, Great Blue Heron, Black-crowned Night-Heron, Northern Harrier, Wilson’s Snipe, Belted Kingfisher, Yellow-bellied Sapsucker, American Pipit, and Savannah Sparrow. I suspect many of the 51 Eastern Bluebirds tallied have sought warmer climes now.

Six species of gulls were counted. The most unusual was a Black-headed Gull. Black-legged Kittiwakes were represented by a fine total of 35.

Shorebird diversity was excellent with the expected Purple Sandpipers and Sanderlings joined by a Killdeer, two Ruddy Turnstones and two Dunlin.

The most common alcid in coastal waters is the Black Guillemot and 10 were found this year. Razorbills usually winter well offshore so the count of 22 birds is noteworthy.

The best rarity on the count was a Yellow-throated Warbler.

The Lewiston/Auburn count was held on December 19. A total of 43 species were found by the 25 participants. The 326 Mallards were by far the most common of the six species of waterfowl found. Two lingering Common Loons were nice finds. Five species of diurnal raptors were found with the dozen Red-tailed Hawks and the two Peregrine Falcons being the most notable.

Red-breasted Nuthatch abundance varies greatly from winter to winter. This year seems to be a bit of a down year; only 14 were found in Lewiston/Auburn.

Lingering birds included a Hermit Thrush and a Field Sparrow. Three Northern Mockingbirds and 60 Cedar Waxwings were good additions to the count. The 50 Northern Cardinals indicate this species continues to increase in Maine; the species was quite uncommon in Maine only 30 years ago. Only two finch species (American Goldfinch and House Finch) were found this year.

The Bunker Hill (in Lincoln County) count produced 50 species on December 21. Eleven species of waterfowl were tallied with a Redhead, a Ring-necked Duck and a dozen Greater Scaup being the most notable.

Birds that normally depart from Maine by this time included a Great Blue Heron, two Eastern Bluebirds and, most unusually, a Vesper Sparrow.

Three Red-bellied Woodpeckers were found along with three other species of woodpeckers: Downy Woodpecker, Hairy Woodpecker and Pileated Woodpecker.

Only two species of finches were found: 114 American Goldfinches and a single House Finch.

The Waterville count was held on December 20 and produced 53 species. Open water was limited but counters were able to find a Greater Scaup, a lingering Ring-necked Duck and a single Barrow’s Goldeneye (multiple individuals of this species are usually found on the Kennebec River here).

Diurnal raptor diversity was good with the highlights being a Rough-legged Hawk, several Red-tailed Hawks and a Merlin.

Two observers must have been amazed to find an Eastern Phoebe, pumping its tail, at this late date. Other unexpected birds included a Lincoln’s Sparrow and a pair of Rusty Blackbirds.

One Bohemian Waxwing was picked out of a flock of Cedar Waxwings. A large dairy farm north of Fairfield usually produces a nice mix of ground-feeding seedeaters. The counters were not disappointed this year, finding Horned Larks, Snow Buntings, and a single Lapland Longspur.

[Originally published on January 10, 2010]

2010-02-13T11:24:00.001-05:00

For the Birds - Life Lists

Shopping lists, grocery lists, to-do lists. People love to keep lists. That habit is found in many birders who keep lists of birds they have seen. Such lists are called life lists.

The first mention of a bird life list that I can find appeared in an editorial in 1927 in the Wilson Journal of Ornithology. A life list was defined as “a total list of birds with which the observer has made a field acquaintance”. The editorial writer advocated listing of species but not subspecies because the latter cannot often be identified in the field. The writer thought that a life list of 150-250 birds would be a reasonable expectation for most regions of the United States. Higher totals would require the observer to travel.

The editorial concluded with thoughts on the value of a life list. Keeping the list and adding to it is certainly enjoyable. But is knowing a few species well better than having a passing acquaintance with many species?

Although the concept of the life list was associated with ornithologists, most people who keep bird life lists are not professional ornithologists. For a portion of these birders, a life list represents the medium of a competitive sport.

The American Birdwatchers’ Association (now the American Birding Association) was organized in 1968 primarily to support birding (and listing) as a hobby. List totals of subscribers were published so members could see how their lists compared to others. The game was on!

A great milestone was reached in 1972. Joe Taylor reported a North American list of 700 species, the first person to reach this then lofty goal.

The ABA continued to grow, fueling the growth of competitive birding, but also through the pages of Birding magazine, providing tips on identification of tricky species and site guides to birding hotspots.

Each year, ABA members have the option of reporting their list totals for publication. Much has changed since Joe Taylor first cracked the 700 species barrier. Increased communication has made reporting of rarities much more efficient. In the 1970’s and 1980’s, one could pay to subscribe to a North American telephone rare-bird-alert to learn of unusual birds on our continent. With the development of the Internet, cell phones and digital cameras, reporting of rarities became even more timely. Now, a birder on a remote Alaskan island can send photographs of a Terek Sandpiper to the world only minutes after taking the photograph.

The twin effects of increased competition and efficient communication can be seen by looking at the most recent Life List report, reporting totals through 2008. One can see that 282 birders have cracked the 700 species barrier and 28 birders have seen 800 species or more. The highest total reported is that of Macklin Smith, an English Professor at the University of Michigan; Smith reports 879 species. The next closest is Ted Koundakjian of California at 868 species.

Competing at this level is difficult because of the time and financial resources required. If a super-rarity shows up in southeastern Arizona, these birders need to make a special trip because their competitors will likely be making the trip.

Both Smith’s and Koundakjian’s lists are notable because they do not contain any heard-only birds. The ABA allows the listing of birds that are heard but not seen. In part, this rule is an effort to minimize disturbance of nocturnal birds like owls or secretive birds like Yellow Rails or Black Rails. These species can usually be reliably identified by voice. There are purists, however, who will not put a species on their life lists unless they see the bird.

For birders with more limited time and money, life lists can be kept at more local levels. People can report state lists for the ABA Life List Report. For Maine, 423 species have been reported in the state. Julie Suchecki reported the highest total of 349 species with Frank Paul a close second at 338. I suspect other birders in the state have comparably impressive lists but choose not to report their totals.

Some people keep county or township lists. Yard lists are popular as well.

Annual lists are kept by many birders. These lists can be over large geographic areas (world list, North American list) or more local areas. For 2008, Doug Hitchcox reported the highest total of species in Maine (219 species).

Some birders do not bother to keep any life lists. Others will maintain lists for their own personal satisfaction but do not report them. And yet others enjoy the competitive side of birding that listing provides.

[Originally published on December 27, 2009]

2010-02-13T11:21:00.000-05:00

For the Birds - Species Concepts III

In the last column, I began a discussion of the different concepts of species used by biologists. How do we know what a “good species” is? The column ended with the Biological Species Concept (BSC, for short), in which the ability to interbreed determines if two populations should be combined into one species.

Determining species limits is tricky because hybrids often occur when two presumed species overlap. Orioles provide a nice example of the changing winds of bird taxonomy. Prior to 1983, birders could see Baltimore Orioles in eastern North America and Bullock’s Orioles in the west. Based on the fact that these two species interbreed at their region of overlap in the Great Plains, the AOU Check-list Committee combined the two species into one, called the Northern Oriole. Subsequent work revealed that the two species have very different molting patterns. DNA comparisons indicate that Baltimore Oriole and Bullock’s Oriole are not even their closest relatives. So the Check-list Committee reversed itself and split Northern Oriole back to two species.

Our current taxonomy has some inconsistencies. The American Black Duck and Mallard interbreed freely. Waterfowl biologists are concerned that hybridization with Mallards may be swamping the genetic constitution of the black ducks. Similarly, the Golden-winged Warbler is declining throughout much of its range, due in part to extensive hybridization with the Blue-winged Warbler (a species that is rapidly increasing its range). So despite the ability of these two pairs of species to interbreed freely, we recognize each pair as two separate species.

Compare that situation to the Yellow-rumped Warbler, one of the most familiar warblers nesting in Maine and indeed throughout North America. Two forms of this species are recognized, our eastern Myrtle Warbler and the western Audubon’s Warbler. Male Myrtle Warblers have white throats and male Audubon’s have yellow throats. The two types of yellow-rumps interbreed in a very limited area in the southern Canadian Rockies. Despite the more limited interbreeding than the two species pairs above, the two distinct forms are combined into a single species.

This discussion leads us to consideration of the last species concept, the Phylogenetic Species Concept (PSC, for short). Advocates of the PSC argue that the ability to interbreed is a misguided approach. Rather, these advocates define a species as a group of individuals that all share at least one characteristic found uniquely in that group. If individuals sometimes interbreed with other species but still maintain those unique characteristics, it’s no big deal. Each species has its own history (or phylogeny). Use of the PSC would cause the Myrtle Warbler and Audubon’s Warblers to be split into two species. The limited interbreeding does not alter that fact that the two types of yellow-rumps have unique throat colors.

Unique songs or calls can be used to define a species under this approach. From the work of Jeff Groth and Tom Hahn, we know that there are at least nine populations of Red Crossbills with distinctive flight calls. The different call types do show some morphological differences and differences in choice of cones they feed on. The PSC would result in these nine call types being split into nine species.

Genetic differences can be used to define species using the PSC. If all individuals in a population have a unique sequence of DNA, that information can be used to define a species. Of course, a DNA sequencer is a bit unwieldy for birders to carry in the field!

One upshot of using the PSC is that the number of recognized species of birds will increase. I have seen one estimate that the number of bird species could be doubled to about 20,000. That is one way to work on your life list.

Regardless of the species definition chosen, biologists will continue to be confused for some species or groups of species. Populations change and diverge through time in response to changing climate, increases in competition or changes in predator numbers. To drive this point home, let us end with Herring Gulls.

Herring Gulls occur around the globe in higher latitudes of the northern hemisphere. European Herring Gulls are the lightest in color. They interbreed with the slightly darker American Herring Gulls. American Herring Gulls from Alaska interbreed with even darker Vega Herring Gulls in Siberia. The Vega gulls interbreed with the darker yet Herring Gulls in central Russia and they interbreed with Lesser Black-backed Gulls in Europe. But at the end of this ring, the Lesser Black-backed Gulls and European Herring Gulls can’t interbreed! Where do we draw the species line?

[Originally published on December 13, 2009]

2010-02-13T11:19:00.000-05:00

For the Birds - Species Concepts II

In the last column, I wrote about the scientific classification of birds. I pointed out that the families and orders into which birds are classified are pigeonholes defined by scientists. The only taxonomic unit that is defined by nature is the species. Recognizing species is not as easy as one might think. We’ll begin to explore this prickly subject today.

A recent scientific review showed that there are over 60 definitions of species. I will collapse this list to three basic concepts and discuss the strengths and weaknesses of each.

The morphological species concept is based on the idea that all members of a species should be similar. Of course similar is a subjective adjective. I like to show my introductory biology class a portrait of the basketball player Wilt Chamberlain next to the jockey Willie Shoemaker. An alien would scarcely suspect that these two mean, differing so much in height and skin color, belong to the same species. Strike one for the morphological species concept.

Sibling species, species that are deceptively similar, also pose a problem for the morphological species concept. Prior to 1973, certain flycatchers with eye-rings and wing-bars were identified as Traill’s Flycatchers. Fieldwork showed that some male Traill’s Flycatchers gave a sneezy fitz-bew song and others gave a fee-bee-o song. Researchers found that some Traill’s females responded only to the fitz-bew songs and others only to the fee-bee-o songs. Traill’s Flycatcher is actually two very similar species: the Willow Flycatcher and the Alder Flycatcher. Distinguishing the two species in the field is nearly impossible and even in-hand identification is not always possible. Strike two for the morphological species concept.

Ernst Mayr, one of the greatest biologists of the 20^th century, developed the biological species concept, defining a species as a population of interbreeding organisms that are reproductively isolated from other populations. This concept is widely held and is the predominant view of the members of the American Ornithologists Union Check-list Committee that rules on taxonomic changes for the birds of the Americas.

The critical aspect of this concept is the ability to breed with other individuals to produce viable offspring. Different species should be unable to hybridize; they should be reproductively isolated even if they are found in the same area. Isolating mechanisms include songs, displays and infertility that prevent members of different species from mating or producing viable young.

Two problems arise with his concept. First, how do you treat populations that are geographically separate from each other? Consider the scrub jay complex. Scrub Jays are very common birds west of the Rocky Mountains, essentially occupying the ecological role of our Blue Jays. But there is a population of Scrub Jays in south Florida. Also, the Scrub Jays on Catalina Island, off the coast of Southern California, look a bit different from western Scrub Jays. How can you apply a test of the ability to interbreed for populations that are not in contact with each other? The answer is that it becomes a judgment call. Formerly, these jays were all treated as one species, the Scrub Jay. More recent work, based in part on DNA differences, has split the scrub jays into the Florida Scrub Jay, Western Scrub Jay and Island Scrub Jay. We still don’t know if these different populations can interbreed. Strike one against the biological species concept.

Another problem is that a lot of birds do hybridize. More than 10% of bird species care capable of creating viable offspring with members of other species. Ducks are the most notorious birds in this regard with over 400 hybrid combinations known. Mallards hybridize with over 50 species of ducks and geese. Wood Ducks hybridize with over 40 species. Over 10% of the American Black Ducks and Mallards in New England are hybrids.

Hybrids occur regularly in wood warblers as well. Lawrence’s Warbler is a well-known hybrid between a Golden-winged Warbler and a Blue-winged Warbler. The Cincinnati Warbler described by Audubon is now known to be a cross between a Blue-winged Warbler and a more distantly related species, the Kentucky Warbler.

Even though hybrids often are capable of reproduction, in some cases their mixed-parentage offspring are not fertile. Some hybrids capable of reproduction may have more difficulty in securing a mate than pure-breed individuals.

But many hybrids can secure mates and produce offspring that are fertile. In such cases, ornithologists measure the proportions of hybrid to “pure” offspring where two populations overlap. The two populations are judged to be the same species if hybrids are common. In the next column, we will see this rule in action. I will also present a third, more controversial, species concept.

[Originally published on November 29, 2009]

2010-02-13T11:16:00.000-05:00

For the Birds - Species Concepts I

Taxonomy is the branch of biological science that is concerned with the classification of organisms. To use birds as an example, all birds are classified into the Class Aves within the Subphylum Vertebrata (which includes all animals with backbones) and the Phylum Chordata (which includes sea squirts as well as vertebrates).

The Class Aves is divided into a number of orders. For example, the Order Gaviiformes includes the loons while the Passeriformes includes all the perching birds. In turn, each order is broken into a number of families. The Corvidae (jays and crows) and the Vireonidae (the vireos) are but two of the many families in the Order Passeriformes. Families are broken down into genera (the singular is genus). Finally, each genus contains one or more species. Following the convention developed by the Swedish taxonomist, Carolus Linnaeus, every species is referred to by its genus and species name. The scientific name of the Black-billed Cuckoo is Coccyzus erythropthalmus. It’s a good thing we have standardized common names for our birds!

Ideally, the taxonomic system should reflect the relatedness of the species within a group of organisms. So, all species that belong to a particular genus are more closely related to each other than they are to other members of their family that are in different genera. Let’s consider the sparrow family, the Emberizidae. Within this family, the White-throated Sparrow and White-crowned Sparrow both belong to the genus Zonotrichia. Our classification suggests these two species are more closely related to each other than either is to the Chipping Sparrow, classified into the genus Spizella. But all the sparrows, classified into many different genera, are all considered more closely related to each other than to any member of another family like the finches (Fringillidae) or tanagers (Thraupidae).

Of all the different levels of a taxonomic system, the species is the only one that is defined by nature. We have techniques that allow us to determine if a population of organisms constitutes a species. All of the other levels are defined by humans. There is no formal definition of what constitutes a genus or a family or an order.

Taxonomy operates on a system of priority. The first classification of a group of organisms is the one that is usually followed. Revisions to taxonomy can be published to reflect better understanding and new discoveries but such revisions have to be reviewed and approved by other taxonomists before an older taxonomy can be changed. As an example, barnacles used to be classified in the Phylum Mollusca, the group that contains snails, clams and squids. Like most mollusks, barnacles have a calcareous shell around the body. Careful examination of the internal structures of barnacles showed them to be crustaceans, more closely related to lobsters, shrimp and crabs. Barnacles were re-classified into the Phylum Arthropoda. The rapid increase in our knowledge of DNA sequences of many organisms has caused us to revise many taxonomic classifications.

Different groups of organisms were originally classified by different taxonomists. Each taxonomist had a subjective notion of how similar species should be to allow them to be classified into the same genus. There are 500 species of marine tropical snails called cone shells. All 500 of these species are classified into the genus Conus. The frog genus Pristimantis contains over 400 species of frogs native to South America and northern Central America. Different taxonomists might have defined each genus more narrowly and might have established ten or more genera for the same groups of species. At the other extreme, some species are considered so distinctive that they are put into their own genus. The Gray Hawk is the only species in the genus Asturina. The distinctive Shoebill from Africa is not only the sole species in its genus but the only member of the family Balaenicipitidae. The Black Skimmer is one of only three species in the family Ryncopidae. Birds are split into smaller genera than many other groups of organisms.

In the end, taxonomy is a way of organizing earth’s biodiversity. A taxonomic system is really a collection of pigeonholes, nested within larger pigeonholes. It is up to each taxonomist to decide how large a genus pigeonhole or a family pigeonhole should be. In other words, all taxonomic units above the level of the species are artificial groupings created by taxonomists.

We recognize the species level as the base of all taxonomy. Species are not artificial units created by scientists but groups determined by the biology of the organisms. However, recognizing a species is tricky and often controversial. We’ll jump into that fray in the next column.

[Originally published on November 15, 2009]

2010-02-13T11:12:00.000-05:00

For the Birds - Bird Sleep

With the arrival of cool weather, I expect activity at your feeders has increased. I like to monitor when the chickadees, goldfinches and other feeder birds leave the feeder in the afternoon. The birds are going off to their roosts and the timing of their departure for their roost, relative to sundown, is remarkably constant from day to day.

At their night-time roosts, most birds spend most of the night sleeping. Birds spend about half of their lives sleeping but the amount of sleep they get depends greatly on the latitude and the season of the year. During the early part of the Maine summer, birds may sleep less than nine hours when the night is so short. On the other hand, Maine birds in the winter sleep more than 15 hours a night.

Birds living in the vicinity of the equator experience near equal days and nights each day so spend twelve hours a day sleeping throughout the year.

Some birds spend the night in communal roosts. European Starlings and American Crows are good local examples. In more southern parts of North America, huge roosting flocks of Common Grackles and Red-winged Blackbirds are common.

Migration poses a real challenge for birds in terms of getting adequate sleep. Most songbird migration occurs at night and then the birds must forage during the following day to restock their fat reserves. Not a lot of time for sleeping.

A recent study of migrating Swainson’s Thrushes revealed a behavior that helps these birds fight sleep deprivation. The birds take minute-long naps through the day. During these short siestas, a thrush will puff its feathers out and squint their eyes. A migrating Swainson’s Thrush will spend up 15% of its day sleeping in these very short bouts.

Many birds choose solitary roosts. Red-tailed Hawks, Bald Eagles, Black-capped Chickadees and Purple Finches are good examples.

Particularly during the winter, the choice of roost site can mean the difference between life and death. Many of our northern finches (Common Redpolls, Pine Siskins, Purple Finches) roost in evergreen trees. Such trees offer protection from the chilling effect of winter winds. The birds can also absorb a little of the infrared radiation emitted by the trees. In the brutal economy of a Maine winter, the little bit of heat absorbed from the environment can be critical for a wintering bird.

Woodpeckers, nuthatches and chickadees will spend the night in cavities, often the same cavities used for nesting during the breeding season. House Finches will seek out the eaves of houses for a relatively warm roost site.

Some birds sleep on the ground. Members of the grouse family are typical of this sleep behavior. Northern Bobwhite arrange themselves in tight circles on the ground with the heads facing outward. If a predator disturbs the roost, the birds explode in all directions, certainly giving the predator a dramatic shock.

The posture of a sleeping bird can important in conserving heat during a long winter night. The unfeathered bill is a potential source of heat loss. Many sleeping birds will turn their head under their scapular feathers while they sleep. Mourning Doves turn their head down, nestling it in their dense breast feathers. Some birds sleep while standing on one leg, reducing by half the heat loss across the unfeathered legs.

Aquatic birds may sleep while floating on the water. The Common Eider, abundant along the Maine coast in the winter, snoozes while bobbing on the ocean surface at night. The down feathers of the eiders, renowned for their warmth, keep the eiders warm.

Some birds are able to sleep while on the wing. Some species of swift spend months in the air without landing. Albatrosses often spend months at sea. Sleeping on the surface of the ocean is possible exposes the birds to fish and whale predators. Similarly, Sooty Terns are reported to stay airborne from the end of one nesting season to the beginning of the next breeding season. Ornithologists believe these birds spend time sleeping in flight.

Have you ever wondered why birds do not fall off their perches while they are sleeping? Songbirds have a flexor tendon in the lower part of each leg. When they perch, the flexor tendon tightens, causing the toes to curl around the perch. The tendon essentially locks, keeping the toes firmly around the perch during sleep. The same type of tendon is useful in raptors when they are carrying prey. Once a fish is in the talons of an Osprey, that fish has no chance.

[Originally published on November 1, 2009]

2010-02-13T11:09:00.000-05:00

For the Birds - Recent Ornithological Literature

This post is a review of recently published articles in ornithology that I hope will be of interest.

Foot waggling in Common Loons

If you have spent much time watching Common Loons, you surely have seen a loon on the water raise one foot into the air and either hold it there briefly or shake it, often several times in succession. This behavior is called a foot waggle. After waggling the foot, a loon may put the foot under the wing, a behavior called shipping.

The reasons for foot waggling have been discussed for years but not adequately tested. Some ornithologists suggest foot waggling occurs most frequently in birds that are about to sleep or rest and interpret foot waggling as a comfort movement. Other scientists think that the large foot of the loon with its extensive system of capillaries may be used to regulate body temperature. A foot out of the water might lose heat quickly by evaporation of water into the air. Other ornithologists have suggested that food waggling may function as a social signal.

A recent paper in the Condor by James Paruk describes his work to investigate the function of the loon foot waggle at several sites in the Upper Peninsula of Michigan. He found that 81% of the foot waggles observed occurred while a loon was either preening or resting. Foot waggling was therefore judged to be primarily a comfort movement. Occasionally, a loon would give a single foot waggle in a stressful situation such as after encounters with boaters or a Bald Eagle or after loud thunder. Because only some loons used the foot waggle in such situations, Paruk claims that the behaviors are idiosyncratic – some birds use the behavior and others do not.

The loons did waggle their feet more on sunny days than on cloudy days. The dark bodies of loons heat up more in direct sunlight. This relationship suggests that regulating body temperature may be a secondary function of foot waggling. By the way, foot waggling is seen in other aquatic birds as well including grebes, Ruddy Ducks, scaups and their relatives, and mergansers.

Tail pumping in Eastern Phoebes

The tail-pumping behavior of a perched phoebe is a good feature to use in identifying this flycatcher. The function of this behavior has been the subject of much conjecture. Michelle Carder and Gary Ritchison recently published an article in the Journal of Field Ornithology that presents a test of possible explanations for the behavior.

They tested four hypotheses by extensive field observations. The first is that phoebes use tail pumping to maintain their balance on a perch. The authors measured tail-pumping rates on perches of different stability (thin versus thick branches) and under different wind speeds. They found no correlations and reject this explanation. A second hypothesis was that phoebes use tail pumping as a territorial display to other males. Through playback experiments, this explanation was also rejected.

Thirdly, tail pumping might be use to aid foraging by flushing insects. The authors found no support for this hypothesis.

The predator-deterrent hypothesis was supported by the author’s data. A phoebe should increase its tail wagging in the presence of a predator to let the predator know “I see you”. Lower rates of tail wagging when predators are not seen may discourage those predators from attacking a phoebe.

Altitudinal ranges of birds and climate change

As global warming proceeds, marked changes occur in the climate of mountains. The warming means that species restricted by temperature can move higher up a mountain.

For mobile species like birds, scientists expect that the distribution along an altitudinal gradient will occur. Birds must move higher up a mountain to find the temperature regime that best suits them.

Recently, Morgan Tingley and colleagues published a paper that explores this phenomenon. They resurveyed bird abundance in the Sierra Nevada mountains of California along four elevational transects, first established nearly a century ago. Climate information indicates that any site along the transects is warmer now than it was a century ago. The workers focused on 53 bird species and found that 48 of them had shifted their range higher up the mountains over the past century.

[Originally published on October 18, 2009]

2009-10-20T10:45:00.002-04:00

For the Birds - Monarch migration

In today’s column, the Monarch Butterfly will serve as an honorary bird. Certainly one of the most easily recognized butterflies, Monarchs occur broadly across the United States and southern Canada.

However, the chances are pretty good that you have seen very few Monarchs this year in Maine. The cool and wet weather may have been a contributing factor to their poor success this year. I recently surveyed volunteers in the Maine Butterfly Survey project. Not one of the 25 respondents reported seeing as many as ten Monarchs this year, although the season may be a bit delayed.

Other species of butterflies like Common Ringlets, Common Wood Nymphs and Silvery Blues that live their entire lives in Maine took a big hit this summer because of our inhospitable June and July weather. These species will likely take a few years to recover their former population sizes.

The Monarch, however, is a migrant. Poor reproduction in Maine will not necessarily translate into lower numbers of Monarchs next year.

The amazing southward migration of Monarchs has been appreciated for quite a while. We have long known that populations west of the Rocky Mountains moved south to winter in about 150 winter roost sites between San Francisco south to northern Baja California. These roost sites are usually within a couple of miles of the Pacific Ocean. Each site usually has between 10,000 and 40,000 butterflies. As you can well imagine, coastal development has threatened a number of these roost sites.

But, where do the eastern migrating Monarchs spend the winter? The answer was not known until 1975 when a researcher named Fred Urquhart announced a surprising discovery. Each fall all of the eastern Monarchs in Canada and the United States empty out, migrating to Oyamel fir forests in the mountains of central Mexico. The fall migration commences in August and continues into December. Urquhart amazed everyone with pictures of millions of Monarchs roosting in layers on trees, weighting down branches.

Ten overwintering sites are known in Mexico. All are within an area of about 500 square miles in a belt of volcanic mountains stretching across Mexico. Conservation biologists are working hard to preserve these habitats and ecotourism is flourishing at these sites. Nevertheless, logging pressure poses a major threat.

As winter gives way to spring, the Monarchs become more active and start to mate. After mating, northward migration begins. Once mated, the butterflies have only a month or so to live. Along the northward migration, the females lay eggs on milkweeds along the way. Milkweed leaves provide the nutrition for the caterpillars. The migrating butterflies continue north and east with some reaching the Gulf coast states before they die. Meanwhile, the eggs laid along the way have hatched and the gluttonous caterpillars grow rapidly. Nine to 14 days after hatching, the caterpillar enters the pupal or chrysalis stage. During the next eight to 11 days, the tissues of the caterpillar are transformed into the body of an adult butterfly.

These newly emerged Monarchs (the offspring of the overwintering generation) continue northward, laying eggs along the way and ultimately perishing. Each female can lay 500 eggs. Most are laid singly on a milkweed plant. In this leapfrog manner, all of the eastern United States and southern Canada are repopulated. The Monarchs that reach us may be the great-grandchildren of the overwintering population!

The Monarchs that will migrate back to central Mexico emerge in the fall. These butterflies do not become reproductive but rather go into reproductive diapause. They will not be able to mate until the following spring on the wintering grounds in Mexico. Unlike the other adults from other generations that have only a month or so to live, these overwintering Monarchs may live for seven months.

Perhaps the most remarkable aspect of this tale is the “hard-wiring” in the migrating Monarchs. Even though they have never made the journey to central Mexico, the migratory behavior and direction are genetically encoded.

Since 1990, Dick Walton and Lincoln Brower have been conducting a Monarch Monitoring Survey at Cape May, New Jersey. At times, more than 300 Monarchs per hour have streamed past the hawk watch platform at Cape May Point. You can see find year-by-year accounts of the Monarch migration there at: http://www.concord.org/~dick/mon.html Numbers for 2009 indicate average to above average counts, lightening the dismal season for Monarchs in northern New England.

I encourage anyone wishing to learn more about these remarkable butterflies to read Sue Halpern’s marvelous book, Four Wings and a Prayer. Her prose is lyrical and her accounts of field expeditions with established Monarch researchers are fascinating.

[First published October 3, 2009]

2009-10-20T10:38:00.002-04:00

For the Birds - Birds and Window Collisions

Human-related activities account for a significant number of bird deaths. Habitat destruction is clearly the most important but the next most important factor is collisions with clear and reflective sheet glass. Such collisions account for at least a billion bird deaths each year in the United States. These deaths are spread over at least 225 species. Compare this mortality with deaths from other human-related factors: 120 million from hunting, 60 million from collisions with moving vehicles, 400,000 from wind turbines and potentially hundreds of millions by cats.

Dan Klem, a professor of biology at Muhlenberg College, has been studying bird kills from glass collisions for the past 35 years. Much of today’s column comes from Klem’s extensive research.

Why do so many birds die from flying into windows? There is little evidence to indicate that birds that hit windows have faulty eyesight. Reduced vision in fog and smoke also plays only a minor role in explaining window kills. The chief explanation seems to be that birds perceive clear windows as open space and attempt to fly through. The likelihood of window kills is increased if there are windows on both sides of a building, producing a see-through effect. Windows with reflective surfaces act as mirrors, fooling birds into thinking that flight is possible through the window.

Bird feeding increases window kills by attracting birds to buildings. The high concentrations of birds at feeders, particularly in the winter, attract bird predators like Sharp-shinned Hawks or Cooper’s Hawks. The appearance of such a predator, loud noises or sudden movements, may cause a panic flight of birds from a feeder with the possibility of fatal window strikes. A short flight of only one meter can produce a fatal collision.

Klem examined 300 fatalities and 31 survivors to determine the types of injury, causes of death, and recovery from collisions. Every fatality showed intracranial bleeding, suggesting that death was caused by ruptured blood vessels in the head and brain damage. Survivors often sustained intracranial bleeding as well and may have died later on from the injury. Bone fractures were relatively rare, indicating the surprising strength of the light bones of birds.

If you find a stunned bird after a window collision, place the bird in a protected enclosure (I use a paper bag), keep the enclosure warm, and provide the bird with food and water.

What can homeowners do to minimize window strikes by birds? The best solution, to eliminate windows altogether, is not acceptable. Covering windows with netting can be expensive and affects the aesthetics of a building. Making windows obvious as obstacles that should be avoided can reduce window kills. Spiders use this strategy to protect their webs. The webs of many spiders have thick, highly visible strands. Flying birds easily see these strands and avoid flying through the webs. Klem's research has shown that placing vertical strips of tape on windows cuts down on window strikes dramatically, particularly if the strips are separated by four inches or less. Horizontal strips are less effective. The black silhouettes of hawks and falcons that can be purchased for placement on windows are not effective unless they are stacked closely together. These silhouettes do not provide enough contrast for birds to realize that windows are obstacles. In new or remodeled homes, architects are encouraged to install windows at a slight angle so that they reflect the ground rather than trees or the sky. Birds are not likely to try to fly into a reflection of the ground. In addition, birds are likely to hit an angled window at an angle and thus soften the force from the collision with the glass.

The placement of bird feeders can also curtail window kills. Klem's studies have shown that placing feeders very close to a window reduces fatal window strikes during panic flights. Although birds may hit the window after they fly up in response to a loud noise or a predator, the birds will not be flying fast enough to suffer harm or death from the collision. An alternative solution is to place your feeders well away from the nearest window. So, the best advice is to either place your feeders within three feet of a window or at least 30 feet away from the window.

One of Klem’s recent publications involved the assistance of 30 trained volunteers from the New York City Audubon Society. The purpose of the study was to determine building and landscape characteristics associated with higher risk of collisions with migrating birds in an urban environment. The research was done in Manhattan. The volunteers monitored 73 facades of buildings throughout the island borough.

The team recorded 475 bird collisions in the fall of 2006 and 74 collisions were in the spring of 2007. Their analyses provide good advice for architectural and landscape designs to reduce collisions: reducing the number of reflective panes in windows, keeping trees away from walls, and reducing ground cover.

[First published September 19, 2009]

2009-10-20T10:35:00.003-04:00

For the Birds - Birder Demography and AOU Check-list Updates

Who Are We?

The U. S. Fish and Wildlife Service has recently released their report, “Birding in the United States: A Demographic and Economic Analysis”. This document offers interesting insight into the popularity and demographics of birding.

Birder is defined rather broadly for the purposes of this report. A birder is someone who has driven at least a mile for the primary purpose of watching birds or someone who closely watches and tries to identify birds around the home. People who happen to see birds while mowing the lawn or kayaking do not qualify as birders.

The report indicates that 48 million of us, 16 years of age or older, are birders. That number translates to 21% of the North American adult population. Backyard birders include 42 million birders. Twenty million birders travel to see birds.

The average birder is 50 years old. Only 8% of citizens between 16 and 24 years of age and only 13% of citizens between 25 and 34 years old are birders. For citizens above 55, birding is more popular with 27% of this age group participating.

The data show a clear pattern of birding participation rate increasing with income level. Birding interest increases with education as well. Only 12% of citizens without a high school degree are birders while 28% of college graduates are birders. Female birders outnumber male birders, 54% to 46%.

Birding is primarily an activity of white people. Over 24% of white citizens classified themselves as birders, contrasting with 8% for Hispanics, 6% for African-Americans and 7% for Asians.

One might expect that people who live outside of major urban areas would be more likely to be birders. That expectation is borne out by the survey. Only 17% of citizens in major urban areas are birders compared to 27% of Americans who live in townships under a population size of 250,000.

The popularity of birding varies greatly among the 50 states. I am pleased to report that Maine with a 39% participation rate is second only to Montana with a 40% participation rate. Other high-ranking states are Vermont (38%), Minnesota (33%), Iowa (33%), South Dakota (32%) and New Hampshire (32%). Birding is least popular in Hawaii (10% participation rate). Four of our most bird-rich states (Florida, Arizona, California and Texas) are near the bottom of the list with participation rates of 17% or lower. Lots of out-of-state birders do visit these states.

Changes to North America bird names

The American Ornithologists Union (AOU) publishes the official Check-list of North American Birds. North America is defined broadly as all countries from Panama north. The Caribbean Islands, Bermuda and the Hawaiian Islands are included as well.

The most recent Check-list, the seventh edition, was published in 1998. Scientific and common names are given for each species along with a brief habitat description and a textual description of the geographic distribution.

The AOU has a Check-list Committee that is responsible for updating the Check-list. Bird distributions change. Ornithological research, especially the analyses of DNA, forces ornithologist to reassess the classification of birds at the genus, family and order level.

The most recent supplement to the Check-list was just published in the Auk, the journal of the AOU. Most of the changes pertain to Central American species. However, some changes are made to birds that occur in Maine. I will restrict my discussion of the changes to those birds. You may wish to update your field guide.

The scientific name of the Boreal Chickadee is changed from Poecile hudsonica to Poecile hudsonicus.

Recent DNA analyses have shown that some of the birds formerly classified as tanagers (family Thraupidae) are actually closer to the cardinals and their relatives (family Cardinalidae). The tanagers that occur in Maine are in this group. So now, Scarlet Tanager, Summer Tanager and Western Tanager should be reclassified into the cardinal family. The committee stopped short of changing the common names. Now we are left with the confusing situation that a Scarlet Tanager is not really a tanager.

In an earlier decision, the Check-list Committee split the old Sharp-tailed Sparrow into two species, the Saltmarsh Sharp-tailed Sparrow and Nelson’s Sharp-tailed Sparrow. Both nest in Maine. That decision is supported by subsequent research but the common names are a mouthful. The committee has changed the names to Saltmarsh Sparrow and Nelson’s Sparrow, respectively.

Lastly, the genus Carduelis contained a number of the small finches. That genus is now split into several genera. For Maine species, change Common Redpoll to Acanthis flammea, Hoary Redpoll to Acanthis hornemanni, Pine Siskin to Spinus pinus and American Goldfinch to Spinus tristis.

[First published September 9, 2009]

2009-10-20T10:28:00.004-04:00

For the Birds - The Fall Migration of Semipalmated Sandpipers

Shorebird migration is well underway now. Most of these migrants we are seeing in Maine belong to species that nest on the arctic tundra. These birds only have time to produce one clutch of young in the brief arctic summer. The birds depart their breeding grounds as soon as possible after nesting. Interestingly, the adults leave before their young can even fly. Obviously, the migratory routes must be hard-wired in the brains of the young birds.

One of these species is a favorite of mine, the Semipalmated Sandpiper. I have written in a previous column about the arduous fall migration of these birds. Most Semipalmated Sandpipers wend their way to the upper Bay of Fundy in July and August. The birds fatten for a couple of weeks and then depart on a southeasterly track en route to Suriname and adjoining South American countries. This flight must be conducted non-stop over the ocean and requires between 48 and 96 hours of sustained flight. The trade winds do provide significant help for the birds once they go south of the 30th parallel of latitude.

In today’s column, I want to discuss some research that I did in Nova Scotia over the course of two summers. In particular, I will describe the intriguing relationship between the Semipalmated Sandpipers and their major prey in the upper Bay of Fundy mudflats.

The prey species is a small, shrimp-like crustacean called Corophium volutator. Reaching a length of 3/8 of an inch (10 millimeters), Corophium live in U-shaped burrows in the intertidal flats of the upper Bay of Fundy. During the summer, the densities of these crustaceans may exceed 100,000 per square meter.

Corophium have two generations each year. One generation is born in May and grows to reproductive size by the middle of July. These adults reproduce in July and August. Their offspring will grow during the fall and reproduce the following spring in May.

The females brood their eggs in a special brood pouch and ultimately release juveniles that make their own burrows as soon as they are released. The young are only about 1 mm long when they leave mom’s brood pouch to strike out on their own. Once reproduction has occurred, adults will live for a few weeks longer at the most.

The annual population cycle of Corophium therefore involves two generations that scarcely overlap: a three-month summer generation and a nine-month overwintering generation.

Migrating Semipalmated Sandpipers rely almost exclusively on Corophium while they are in the upper Bay of Fundy. The sandpipers are adept at detecting the Corophium in the sediment with their sensitive bills and extracting them. A successful peck by a Semipalmated Sandpiper is easily determined because the Corophium struggles in the bill of the sandpiper. By analyzing videotapes of feeding sandpipers, I was able to quantify the number of Corophium that a sandpiper takes per minute.

I did my research on the mudflat at Avonport in the Minas Basin of the Bay of Fundy. The tidal range there is huge: 35 to 50 feet between high and low tide depending on the stage of the moon. At low tide, a tremendous area of intertidal mud is exposed, giving the Semipalmated Sandpipers access to lots of Corophium.

Around 40,000 Semipalmated Sandpipers foraged on the Avonport flats. I found that each sandpiper ate an average of 17 Corophium per minute! The birds feed both during the day and night when the tide is out. Each sandpiper eats well over 10,000 Corophium per day. That is how the sandpipers can double their weight in just two weeks as they store the necessary fat to fuel their migration to South America.

We also know that Semipalmated Sandpipers choose the large Corophium to consume. As it turns out, I was able to show that Semipalmated Sandpipers are effectively managing their prey population.

When the Semipalmated Sandpipers arrive in July and August, the Corophium born in May are fully grown and are reproducing. Those are the prey the sandpipers go after. Because the adults live for a few weeks after reproducing, they compete with their offspring for food and space in the mudflat. By removing the large Corophium, the sandpipers improve the survivorship of the newly born Corophium. The large Corophium have mostly finished reproducing so their removal by the sandpipers does not affect the population to a great degree.

So, by preying on the large Corophium, the sandpipers increase the number of Corophium that will overwinter. Those Corophium will produce the summer generation in May that will provide food for the gluttonous sandpipers the following July and August.

[First published August 22, 2009]

2009-10-20T10:17:00.005-04:00

For the Birds - Bird Eponyms

Blackburnian Warbler, Wilson’s Storm-Petrel, Swainson’s Thrush, Lincoln’s Sparrow. The common names of all of these birds, common in Maine, are based on a person’s name. I’ll bet most of these people aren’t familiar to you. In today’s column, I will give you a little background on the people whose names are commemorated in the bird names.

The Blackburnian Warbler is one of our most striking warblers with its fiery orange throat and bold black plumage above. This warbler is named after either Anna Blackburne (1726-1793) or her brother, Ashton Blackburne (1730-1780). Anna was an English naturalist. She never visited the New World but did have a strong interest in the birds of the New World. She maintained a collection of North American birds in her natural history museum in Orford in the north of England. Ashton moved to North America and lived in Hempstead, New York. He collected birds in Connecticut, New York and New Jersey that he sent to his sister for her museum. Among the specimens Ashton collected was a Blackburnian Warbler. Thomas Pennant, a naturalist from Orford, saw the specimen in Anne’s collection and prepared the first scientific description of the species. He gave it the name of Blackburnian Warbler but it is not clear if Pennant named the warbler for Ashton or Anne.

The Wilson whose name is commemorated in Wilson’s Storm-Petrel, Wilson’s Plover, Wilson’s Phalarope, Wilson’s Warbler and Wilson’s Snipe is Alexander Wilson (1766-1813). Wilson played an important role in the development of North American ornithology.

Wilson was a Scot who immigrated to the United States in 1794. He taught school for seven years in the Philadelphia area and then decided to make a collection of the birds of eastern North America. From 1803 until his death in 1814, Wilson devoted himself to producing the first book on the birds of North America, which he called American Ornithology.

Wilson’s travels took from Philadelphia along the eastern seaboard to Savannah, Georgia and then north via boat to New York. Another trip took him from Philadelphia to the southeast through Ohio, Kentucky, Tennessee, Mississippi and Louisiana with another boat trip back to New York from New Orleans. His visit to Natchez provided one of the ornithological highlights of his life, the darkening of the skies for hours by millions and millions of Passenger Pigeons.

Wilson was a contemporary of Audubon and they met briefly. Wilson’s artistic skills were rudimentary compared to Audubon but Wilson’s keen eye and perseverance made him a better field ornithologist than Audubon. In addition to the bird species listed above, Wilson’s name is commemorated in the name of one of the major ornithological associations in North America, the Wilson Ornithological Society.

Swainson’s Thrush was named after the Englishman, William Swainson (1789-1855). He had an early interest in nature. His father secured a post for him in Italy in 1808, which gave him plenty of time to study animals, particularly fish and snails. Poor health forced him from the army in 1815 but by 1816, he felt well enough to travel to Brazil for a collecting expedition. He returned to England with 760 bird specimens and large numbers of other species.

Swainson developed skills as a wildlife artist, drawing the biological material he had collected. In fact, he was a far more prolific wildlife artist than Audubon. Based on specimens collected by William Bullock in northern Mexico, Swainson drew and described a number of birds common in the United States including Acorn Woodpecker, Black Phoebe, Violet-green Swallow and Western Bluebird.

Audubon visited Swainson and his family on a trip to England. Audubon asked Swainson to help write the Ornithological Biography, the text that would accompany Audubon’s volumes of prints, The Birds of North America. Swainson refused because Audubon would not give him co-authorship nor a sufficient fee.

Swainson’s name is commemorated in three species: the widespread western raptor, Swainson’s Hawk; the southeastern Swainson ‘s Warbler and our Swainson’s Thrush.

Lincoln’s Sparrow is a fairly common breeder in bogs and cleacuts in the northern half of Maine. The name commemorates a Mainer, Thomas Lincoln (1812-1883). Lincoln met John James Audubon in 1832 and accompanied Audubon on an expedition to Labrador in 1833. Their trip began in Eastport and included stops in Nova Scotia and Newfoundland. The only new species discovered on this expedition was a sparrow, which Audubon described and named after his companion.

After the trip was over, Lincoln returned to the family estate in Dennysville and never did much traveling after that. He studied briefly at Bowdoin College but left before receiving a degree. He and his brother managed the 10,000 acres of the family property. The Lincoln house still stands. It is now the Lincoln House Country Inn, the oldest house in Dennysville.

[First published August 8, 2009]

2009-10-20T10:13:00.001-04:00

For the Birds - Precocial versus Altricial Development

The development of birds can be classified into one of two main types: precocial and altricial. Precocial birds, like chickens, ducks and owls, hatch out with a warm covering of down feathers. A precocial chick can keep its body reasonably warm in the absence of heat from an incubating parent. Some precocial chicks can feed themselves soon after hatching. A Lesser Scaup duckling can swim, dive and catch fish only three days after hatching. Others, like gulls and terns, depend on their parents for food.

Precocial chicks are quite mobile on the ground or in the water soon after hatching. However, it takes a good bit of time, often a couple of months, before they are able to fly. Parents of precocial chicks must spend a fair amount of time watching out for predators looking to make a flightless chick into a meal.

After a period of time, a precocial chick learns to fly. The act of taking the first flight is called fledging. The amount of care given to precocial chicks before and after fledging varies. Sandpipers, like the Semipalmated Sandpiper, leave their flightless young on the arctic tundra and begin their migration southward. The young, with the abundant supply of insects on the tundra in the summer, can fend for themselves. Ultimately, the sandpiper chicks fledge and, guided by a remarkable navigational sense, follow on the heels of the parents two or three week later. Canada Geese tend their young throughout the nestling and fledging periods. The families migrate south together.

Altricial development, the other major developmental type in birds, is characteristic of all songbirds, woodpeckers, swifts, kingfishers, pigeons and hummingbirds. The young hatch as helpless, naked birds. Their eyes are not open and they are unable to even hold their heads up. The young hatchlings cannot maintain their body temperature by themselves for even a short period of time. As a result, one of the parents must incubate the young to keep them warm. This incubation, usually done by the mother, is made possible by the presence of a brood patch on the underside of the body. This brood patch has no feathers and has a rich supply of blood vessels to allow the quick transfer of heat from the parent to the young.

The young must be fed by the adults and rapidly begin to add weight and feathers. The incubation period in most songbirds lasts between eleven and fourteen days. The mother has to spend less and less time incubating the young as they grow as their feathers develop. By the time the nestling period is ending, the chicks have voracious appetites that often tax the abilities of the parents to provide food.

After the nestling period, the young are ready to fledge. The work of the parents is not over although the nest is abandoned once the young fledge. The fledglings follow their parents around are still fed by the parents. You can see the begging behavior of recently fledged young at your feeder. After a period of two or three weeks, the fledglings have become proficient fliers and good foragers so the family unit breaks down. The fledglings are now on their own.

So which is better, precocial or altricial development? Precocial development has the advantage of reducing the time spent in incubating the nestlings as the chicks are born with a covering of down. Precocial chicks can find much of their own food, freeing the parents from an additional energy drain. However, the time to fledging takes a long time. From hatching to fledging for a Ruffed Grouse takes over two months. Hawks and owl chicks may take three months or more to fledge. That’s a long time to avoid predators without the benefit of flying.

Altricial development presents a tremendous challenge for the parents. After hatching, the young have to be fed and incubated. However, the development is quite rapid. After hatching, the young can be fledged and independent in less than a month. In fact, some of our songbirds like House Wrens and Eastern Bluebirds will even have two broods of young in a single season.

The tradeoff then is for parents to work really hard for a relatively short period of time (altricial development) or invest less energy in tending the young on a daily basis but have young which are at risk from predators for a long time because they take so long to fledge (precocial development).

[First published July 25, 2009]

2009-10-20T10:05:00.004-04:00

For the Birds - Clutch Size Variation

Most of the birds in Maine are in the process of nesting now. Among the different bird species, there is great variation in many facets of reproduction. For instance, whether one or both parents brood, the type and location of the nest, the size of the eggs.

One striking feature that varies widely among different species is clutch size, the number of eggs laid in a single nesting attempt. Some birds (albatrosses, petrels, some penguins and some terns) have a clutch size of only one. Hummingbirds and doves always have clutch sizes of two. At the other extreme, some ducks and geese, pheasants and rails may have clutch sizes as high as 20 eggs. Our songbirds have clutch sizes varying between two and 12, depending on species.

Why is there such striking variation in clutch size among different species? This question has been the basis of a great deal of research. In this column, I will briefly introduce some of the findings of this body of research.

To begin, we must realize that reproduction is a taxing experience for birds. Birds that undertake a particularly heavy reproductive effort in one year may reduce their chances of surviving to reproduce the next year. Birds have to make a trade-off between producing very large clutches in a short life and moderate-sized clutches over a longer life.

David Lack, a British ornithologist, was one of the first scientists to rigorously study clutch size variation in birds. He came to the conclusion that a female bird should lay the number of eggs that will produce the most fledged, independent offspring.

Let’s consider Lack’s conclusion for three females which lay three, five and seven eggs, respectively. The female and her mate with only three eggs will probably succeed in fledging three young. The pair with five eggs will have to work harder but still might lose only one chick, fledging four young. The pair with seven eggs have bitten off more than they can chew. The demands of the seven hungry chicks are too much for the parents and perhaps four of the seven chicks will die from starvation. So, what is the best clutch size to have for this species? A clutch size of five - a trade-off between ambition and caution. The pair with only three eggs is not ambitious enough; the pair with seven eggs is too ambitious.

Ornithologists have tested Lack’s prediction by altering the clutch sizes of birds. One species that has been studied intensively is the Tree Swallow. These birds frequently nest in nestboxes at high densities, making it easy for an ornithologist to monitor large numbers of nests. Tree Swallows usually lay five eggs. Experiments are done by removing one or two eggs from some nests and placing them in other nests. After the egg-switching, some nests have three, four, five, six and seven eggs. The results largely confirm Lack’s prediction. A clutch size of five is the most productive clutch.

In other species, that have been examined, birds lay one less than the most productive clutch. Scientists believe that these birds are cutting back on their reproductive effort in a single year to increase their chances of having a long life.

Clutch size within a species often shows striking variation with latitude. The typical pattern is that tropical members of a species have lower clutch sizes than members of the same species that live in the temperate zone. For instance, female Northern Flickers that live in the tropics only lay clutches of three or four eggs while flickers in the northern U. S. A. and Canada may have ten or more eggs.

One possible explanation for this variation is the number of predators. The tropics have many more predators that are threats to eggs and nestlings, including snakes, other birds and various mammals. The chances of a nest being found and destroyed by a predator in the tropics is very high. In the temperate zone, the number of predators is much reduced. Many temperate nests are never discovered by predators.

Ornithologists therefore argue that tropical birds should not invest heavily in a single clutch because it is likely to be lost. It’s not prudent to make a large investment in a risky environment. It is much better to have a low clutch size, allowing the parents to live a longer life. With luck, one of the many clutches a female will lay over her lifetime will escape the predators. On the other hand, a temperate bird does not have the same high risk from predators so can lay a bigger clutch. It’s OK to make a large investment if there is little chance of losing it all.

[First published June 27, 2009]

2009-07-20T22:13:00.003-04:00

For the Birds - Review of Ghost Bird

Today’s column is a review of a movie that is premiering now in the United States as part of the Maine International Film Festival in Waterville. The movie is called Ghost Bird and details the controversy over the recent claims that the Ivory-billed Woodpecker still lives. The film was produced and directed by Scott Crocker, a Bowdoin College graduate.

April 28, 2005 was a great day for birders. The Cornell Laboratory of Ornithology held a press conference to announce the finding of an Ivory-billed Woodpecker in eastern Arkansas. Prior to this sighting, this largest of North American woodpeckers was last documented by photograph in 1941.

Over the years, Sightings of Ivory-billed Woodpeckers, some more credible than others, were reported regularly from Louisiana, Florida and more recently Arkansas. None of these observers managed to get a photograph or movie of the birds.

The chance of confusing a Pileated Woodpecker for an Ivory-billed Woodpecker is high, particularly if the sighting is brief. Nevertheless, a spate of sightings from the Cache River in eastern Arkansas was convincing enough for the Cornell Laboratory of Ornithology to mount a large expedition there in the fall of 2004.

Their best evidence for an Ivory-billed Woodpecker was a brief videotape, taken by David Luneau, a professor electronics at the University of Arkansas-Little Rock. Luneau kept his videocamera recording on the gunwale of his canoe and by luck captured a brief flight of a large woodpecker.

The Cornell team also had a series of automated recording devices throughout the Cache River swamp. Recordings were captured of the “kent” calls that Ivory-bills give as well as the double-tap knocks the birds use to communicate.

The elation of a number of ornithologists and birders flagged upon examination of the data. I think the words of Carl Sagan, the eminent astronomer and stalwart of the skeptic movement in the United States, are appropriate in this case: “Extraordinary claims require extraordinary evidence.”

A close examination of the Luneau video convinced some ornithologists that the bird was actually a Pileated Woodpecker rather than an Ivory-bill. The acoustic evidence was questioned because Blue Jays give a “kent” call, even in areas where Ivory-billed Woodpeckers never occurred. Pileated Woodpeckers will give double tap signals.

Ghost Bird explores the impact of the claimed Ivory-billed sightings on the town of Brinkley, Arkansas. According to one citizen, only one person in Brinkley even knew what an Ivory-billed Woodpecker was before the 2005 announcement. At least six businesses have sprung up in Brinkley, all capitalizing on the Ivory-billed Woodpecker. Where else can you get a woodpecker haircut for $25?

Crocker reviews the data used to support the claim of living Ivory-billed Woodpeckers, including multiple showings of the Luneau video. We see lots of footage of the Cache River swamps.

Two skeptical scientists are extensively interviewed. Dr. Jerry Jackson of the Florida Gulf Coast University is the eminent living authority on Ivory-billed Woodpeckers and has conducted searches for these birds. Dr. Rick Prum of Yale University provides his perspective as well.

David Sibley, the author of the best-selling field guide on North American birds, went to Arkansas after the initial announcement. He noted that earlier workers found that Ivory-billed Woodpeckers preferred to forage on Nuttall oaks. In eight days of dawn to dusk field work, Sibley found no evidence of woodpecker excavations or bark stripping on these oaks.

Crocker does a nice job of documenting the history of the decline of the Ivory-billed Woodpecker. Jim Tanner studied Ivory-billed Woodpeckers in the Singer Tract of Louisiana between 1937 and 1941 for his doctoral research at Cornell University. He and his wife Nancy saw and photographed Ivory-bills there for the last time in 1941. Nancy Tanner is still living, and, in the film, offered a fascinating glimpse into history.

The Cornell Laboratory of Ornithology continues to maintain that their evidence is sufficient to demonstrate that the Ivory-billed Woodpecker still survives. Unfortunately, the Lab would not allow any of their employees to be interviewed for this documentary.

The initial excitement over the re-discovery of the Ivory-billed Woodpecker led to changes in funding for conservation. The U. S. Fish and Wildlife Service provided an initial $10 million dollars to help conserve the Ivory-bill. These funds had to be provided by taking money from other projects designated for the protection of other endangered species. An additional $27 million was provided in 2007. A number of conservation biologists have questioned this re-allocation of limited funds.

[Originally published on July 7, 2009]

2009-07-20T22:11:00.003-04:00

For the Birds - Bird Nests

A characteristic feature of all bird species is a nest in which eggs are laid. Nests range from small depressions in the forest floor to massive structures weighing more than a ton. In today’s column, I will provide an overview of the diversity of bird nests.

The simplest nests are scrapes on the forest floor, fields or beaches. The nest of aKilldeer is a good local example. The female lays four eggs in a nest scrape just big enough to contain the eggs. As you would expect, the eggs are well camouflaged. In the woods, American Woodcocks and Whip-poor-wills create nest scrapes for their eggs. For most species that create nest scrapes, little effort is made to line the nests with soft material. Birds that make nest scrapes spend very little energy in making a place to lay eggs and raise their young.

Most birds construct a bowl-shaped nest just large enough to fit an adult’s body. Let’s use an American Robin nest as a typical example of a bowl-shaped nest. Robins are not great architects but still have a remarkably complex nest. The outer part of the nest is formed of twigs, coarse grass and sometimes pieces of cloth, string or other human-made products. This outer layer gives the nest strength. Within this outer layer, robins place a smooth layer of mud. Finally, a layer of fine grasses is laid down to surround the eggs and aid in insulation. Once the outer part of the nest is built, the female sits in the middle of the nest for the rest of the construction. A snug fit is therefore guaranteed for the incubating mother. The nest is usually in a tree between three and 25 feet high.

Other species use specific materials for the inner lining of their nests. Palm Warblers, a ground-nesting species in bogs, often place Ruffed Grouse feathers in their nests. Tree Swallows line their nests with feathers, particularly white ones. Ruby-throated Hummingbirds create tiny nests to hold their two eggs. The nest is made of down and small pieces of plant material bound together with spider webs. The outer part of the bowl is covered with bits of lichens to aid camouflage. Black-capped Chickadees make their nests in a tree cavity. The outer part of the nest is made of moss and the inner part of spider webs, soft grasses and plant down.

Waterbirds typically create bowl-shaped nests on the margins of lakes or ponds or even on floating vegetation. In most cases, the outer layer of the nest is made primarily of vegetation. If water levels rise, waterbirds will quickly add additional vegetation to keep the inner part of the nest dry. The inner lining is made in part of down feathers that the female pulls from her breast. These down feathers create a wonderfully warm place for the eggs. You take advantage of the excellent insulating qualities of duck down if you own a down coat or sleeping bag.

The largest nests in Maine are made by birds of prey. An Osprey nest may be five feet across. The outer portion is made of sticks and miscellaneous debris. The inner lining is made of smaller twigs, grasses and other soft material. Both the male and female participate in nest building. The male tends to bring material to the nest site and the female incorporates the material into the nest.

The largest nests in Maine are made by Bald Eagles. Some nests may be eight feet in diameter and 12 feet high. The weight may exceed one ton! Like Ospreys, Bald Eagles use the same nests year after year, adding material to the nest each spring. Great Horned Owls will readily adopt an abandoned Osprey or eagle nest.

Some of our birds place domes over the tops of their nests. Such nests are characteristic of many of our wrens. The family name for the wrens, the Troglodytidae, comes from the Greek for cave dweller, reflecting the shape of the nest. One of our most common warblers, the Ovenbird, builds a domed nest on the forest floor. The shape of the nest suggests a Dutch oven. By the way, there is an unrelated group of tropical birds called ovenbirds that create clay-shaped, domed nests which look just like a brick oven.

Distinctive nests are made by Baltimore Orioles. Their nests are made of grasses, vines, and hair. The nest is a deep pouch, bound to the forks of a branch at the rim. Two sprites of the Maine woods, the Ruby-crowned Kinglet and Golden-crowned Kinglet also create hanging nests that are much smaller and more difficult to see than oriole nests.

[Originally published on June 27, 2009]

2009-07-20T22:07:00.003-04:00

For the Birds - Human Face Recognition by Northern Mockingbirds; "Wealthy" Song Sparrows

In the past month, two recently published research articles captured my attention. I’ll review these two studies in today’s column.

Northern Mockingbirds

The first paper documents the ability of Northern Mockingbirds to recognize particular human faces. This work is significant because it is the first research to show a wild animal can recognize individuals of a different species.

The work was done by Douglas Levey and his students at the University of Florida. The Gainesville campus has a large population of nesting mockingbirds. With 51,000 students walking around the campus, a nesting pair of mockingbirds will have around 15,000 humans walking within five meters of a nest during a nesting cycle (about 23 days). Most of these passers-by are ignored by the mockingbirds. Occasionally, a mockingbird will give loud alarm calls, dive bomb or even graze the head of a human. Levey’s team tested the hypothesis that mockingbirds can distinguish threatening humans from people that simply walk past, usually unaware there is even a nest present.

Levey enlisted the assistance of a number of students. The team located mockingbird nests, usually just a few feet above the ground in shrubbery, and set up an experimental protocol. For four days in a row, a student would walk to the nest and stand at the nest for 30 seconds. During the last 15 seconds, the student would put her/his hand on the rim of the nest. The students never touched the eggs or nestlings.

After only two days, the mockingbirds increased their aggressive response to the student even though the student approached the nest from a different direction and wore different clothing. The female mockingbird would leave the nest more quickly, alarm calling would increase and dive-bombing of the student would become more frequent. The intensity of the mockingbirds’ responses increased on the third and fourth days.

Now, the really interesting part. On the fifth day, a different student would approach the nest and stand close for 30 seconds, again with a hand on the nest for 15 seconds. The mockingbirds did not respond aggressively. The birds did not recognize this new intruder as a threat.

The ability of the mockingbirds to perceive their environment in such detail surely helps explain why mockingbirds coexist so well with humans in urban environments.

Song Sparrow

Wealth has its advantages. Well-to-do parents may send their children to the finest private schools. Presumably, such kids will have advantages in life compared to the rest of us from families with more modest incomes. However, recent work by Liana Zanette of the University of Western Ontario on Song Sparrows challenges this idea.

In particular, Zanette was interested in how food influences nestling growth and development. She began her study by raising Song Sparrow nestlings in the laboratory. Some were given only adequate food and others were given much higher quality food. The nestlings on the better diets grew larger than the nestlings on the poor diets. Importantly, the birds on the better diet developed larger brains and a larger repertoire of songs. We know that female Song Sparrows choose mates with larger song repertoires. So, based on this laboratory work, Zanette expected better-fed nestlings in the field to thrive.

In British Columbia, Zanette mapped the territories of a number of Song Sparrows. She put out bird feeders in the middle of half of the territories. Thus, half of the Song Sparrow pairs in the study had access to extra food. The remaining territories had no feeders and served as an experimental control.

As expected, the parents on the territories with bird feeders had more energy they could devote to their reproductive effort. Zanette expected that those females would lay larger eggs than the females on the control territories. Larger eggs lead to larger nestlings with larger brains and, for males, larger song repertoires.

In fact, just the opposite result happened. Eggs and nestlings from food-supplemented pairs were smaller those from control pairs. Rather than produce higher quality young, the Song Sparrows with supplemental food produced more eggs. The eggs were smaller on average than those produced by females on control territories. The male nestlings grew up to develop smaller song repertoires than males from control territories. The females chose quantity over quality.

The parents on a food-supplemented territory had to spread the food they collected for their nestlings among more individuals. So much for the idea that wealthy parents produce offspring with significant advantages!

Zanette found that food-supplemented parents gave more food to the oldest male nestlings. That preferred treatment allowed the sons to become as large as nestlings from control areas. However, their brain growth never caught up.

[Originally published on June 13, 2009]

2009-07-20T22:04:00.002-04:00

For the Birds - Life List by Olivia Gentile

It all began with a Blackburnian Warbler in the spring of 1965. Phoebe Snetsinger was living in Minnesota with her husband and four children. She was 34 years old. A neighbor invited Phoebe to go birding with her. Phoebe’s glimpse of the brilliant orange throat of the Blackburnian Warbler marked the beginning of a burning interest, even an obsession, with birds.

To cut to the chase, Phoebe became the first person to see 8,000 species of birds. With roughly 10,000 species of birds in the world, that achievement is truly remarkable.

The story of the successful quest to see 8,000 species is chronicled in Olivia Gentile’s excellent biography, Life List. Gentile weaves two threads throughout the biography: a description of many of the adventure-filled trips Phoebe took over the years to add to her life list and an examination of Phoebe’s personality, motivations and family relationships. Phoebe largely lived her life on her own terms.

In 1967, the Snetsingers moved to the St. Louis area. Phoebe joined a nature club in Webster Groves. She was a regular on the club’s Thursday’s birding trips. Her skills grew. Her competitive spirit pushed her to surpass the record of 275 species seen in one year in the St. Louis area.

In 1969, the American Birding Association was born. The goals of this organization were to promote the competitive aspects of birding, to promote birding as a sport. Each year, the ABA publishes life list totals for various regions (state lists, North American lists, world lists). A member of the Webster Groves club, Bertha Massie, inspired Phoebe. Bertha had seen over 3000 species of birds in the world and she had the highest world life list of any woman at the time.

Phoebe’s father died in 1971. He had established a hugely successful advertising firm. Phoebe inherited a portion of her father’s wealth that gave her the means for all the international travel to come.

She took a birding trip to the Galapagos Islands in 1976 with her son and another to Kenya in 1977. On the latter trip, she saw 600 species of birds, nearly doubling her life list. She was hooked!

In 1981, Phoebe found a lump in her armpit that turned out to be a malignant tumor. Although tests showed the cancer had not spread, doctors gave Phoebe a devastating prognosis: three more months of good health and death within a year.

Phoebe decided to go on an Alaskan birding trip that she had signed up for before her cancer diagnosis. The trip went well and set the tone for much of the rest of her life. In her words, she was birding on borrowed time.

A year later, Phoebe was feeling fine and the cancer had not spread to other parts of her body. The cancer would appear two more times in her lymph nodes over the rest of her life but never metastasized.

Phoebe began traveling widely on birding expeditions. The attainment of one threshold, like 5000 species on her world life list, led her to want more. She ultimately decided to shoot for the goal of 8000 species. Gentile chronicles Phoebe’s successful quest in an engaging style.

Phoebe was a meticulous note keeper. She maintained an extensive collection of notecards on every bird she saw. During the last 15 years of her life, she was usually birding in far-flung places for at least half of the year and writing up her notes the rest of the time.

Phoebe was a headstrong woman. She broke some bones in her right wrist on one trip but soldiered on lest she miss a life bird or two. Her wrist never fully recovered. She noted the recurrence of her cancer before one trip but decided to wait for treatment until after the expedition! She suffered a brutal assault in Papua New Guinea.

Phoebe’s accomplishments came at the expense of her family. She missed one daughter’s wedding and forced the rescheduling of another. She was with her mother when she died but left for a birding trip before the funeral. Her husband had to seal with her extended absences and preoccupation with her notecards when she was at home.

Ironically, Phoebe died in a car crash in Madagascar in 1999 on a birding trip. Cancer never beat her.

[Originally published on May 31, 2009]

2009-07-20T21:58:00.003-04:00

For the Birds -Maine River Project; Birds in the News

Volunteer Opportunity for Maine Birders

Maine birders and other naturalists have a long history of participation in citizen-science projects. In today’s column, I want to let you know about a new volunteer-based bird project to assess the impact of dams on the birds that use rivers.

Specifically, two dams on the Penobscot River are scheduled for removal in 2011. Volunteers will be sampling the birds of the Penobscot River before and after the removal of the dams.

An essential part of this study will be monitoring control rivers to document any changes in bird abundance over the next few years that are not related to the removal of dams. So rivers like the Kennebec and the Androscoggin need to be monitored as well.

The protocol is straightforward. Each volunteer chooses a section of a river. From a single point, the volunteer monitors birds for twenty minutes, recording the number of birds seen in four consecutive five-minute intervals.

The primary focus is on counting riverine birds that feed on aquatic food resources including cormorants, Bald Eagles, Osprey, waterfowl, herons, shorebirds, gulls, kingfishers, and some songbirds that forage extensively on aquatic insects such as Tree Swallows, Eastern Kingbirds, and Cedar Waxwings. Other species that happen to occur near rivers can be recorded incidentally if you wish.

The river section needs to be surveyed every two weeks during the spring (ice-out until early June) and fall (late August into November) migration periods. Summer counts can be less frequent and winter counts are not essential. Counts should be conducted in the morning.

The project is being led by Erynn Call, a doctoral student in the Department of Wildlife Ecology at the University of Maine. If you are interested in censusing one or more sections of a Maine river, you can contact her by email (erynn.call@maine.edu), letter (Department of Wildlife Ecology, 5755 Nutting Hall , University of Maine, Orono, Maine 04469-5755) or telephone (207-581-2921).

I hope you will consider adopting a section or two of a Maine river for this project. You would be making a valuable contribution to an important project. And, your participation will give you an excuse to go birding!

All About Birds website

The Cornell Laboratory of Ornithology has revised its impressive All about Birds website (http://www.allaboutbirds.org). You can find high-quality images and informative accounts of over 500 bird species. You can listen to vocalizations of many species of birds. Descriptions of favorite birding areas of Lab ornithologists throughout the United States are just a click away.

A brand-new feature is a series of free web videos, called Inside Birding. Two experienced ornithologists, Jessie Barry and Chris Wood, share their tips, tools and techniques for identifying our feathered friends. The first four videos describe their “four keys” to bird identification: size and shape, color pattern, behavior, and habitat. The videos are geared to beginning birders but will be of value to more experienced birders.

Sad News about Whooping Cranes

The Whooping Crane is one of the most endangered bird species in North America. In 1941, the population was only 21 individuals. With a combined effort of habitat preservation, captive breeding and cross-fostering with Sandhill Cranes, the population rose to more than 300 birds in the wild and another 145 in captivity.

One of the world’s two remaining flocks of Whooping Cranes overwinters at the Aransas National Wildlife Refuge in Texas. These birds breed at the Wood Buffalo National Park in northern Alberta.

Last fall, nearly 300 Whooping Cranes departed from Alberta on their migration to Aransas. Unfortunately, 34 of the birds failed to arrive in Texas. Another six adults and 15 chicks did not survive the winter in Texas.

This population of Whooping Cranes therefore lost a fifth of its members over the past six months. Wildlife biologists implicate drought and disease for the deaths of the wintering birds.

Non-Native Purple Swamphen in Florida

In 1996 a family of about six Purple Swamphens were documented for the first time in south Florida. This species is related to the native Purple Gallinule and Common Moorhen that occur naturally in Florida. The swamphen population has exploded since their introduction. Conservation biologists are concerned because the swamphens prey on the eggs and nestlings of native waterbirds and compete for breeding habitat with other marsh birds.

Alarmed, Florida wildlife officials had hunters shoot as many of the swamphens as they could find. This hunting resulted in the extermination of 3,200 birds over a 2.5 year period. This hunting program was not effective and has been discontinued. The Purple Swamphens seem to be firmly established in at least three south Florida counties.

[Originally published on May 15. 2009]

2009-07-20T21:56:00.002-04:00

For the Birds - Ruby-throated Hummingbird

The Ruby-throated Hummingbird has to be one of most eagerly anticipated birds among our migratory breeding birds. The acrobatic flight of hummingbirds, their iridescent colors and their small size endear hummingbirds to many people.

The hummingbird family is one of the largest of the birds with 328 recognized species. Hummingbirds are birds of the New World with the majority found in the tropics of Central and South America. In North America, only about 20 species occur regularly and only one, the Ruby-throated Hummingbird, breeds in eastern North America.

The Ruby-throated Hummingbird is one of the smaller hummingbirds. A typical one weighs a little more than 3 grams, about the weight of a penny. The smallest hummingbirds are the Bee Hummingbird from Cuba and the Reddish Hermit from Brazil and Guyana, which weigh only 2 grams. On the larger side, the South America sicklebills and the Sword-billed Hummingbird weigh 12-14 grams, a little more than a chickadee. The Sword-billed Hummingbird has the longest bill of any hummingbird at an astonishing five inches! The largest of all hummingbirds is the appropriately named Giant Hummingbird, which tops the scales at 21 g.

Ruby-throated Hummingbirds spend the winter between southern Mexico and western Panama. In migration, some individuals undertake a non-stop migration of 1000 miles across the Gulf of Mexico. The birds have to put on extra fat to fuel this expensive flight. Feeding on nectar and insects, a Ruby-throated Hummingbird will double its weight before it departs across the Gulf of Mexico.

Recent observations indicate that some Ruby-throated Hummingbirds prefer to migrate along the eastern coast of Mexico to reach the United States, a longer but perhaps less demanding migration.

To increase our understanding of Ruby-throated Hummingbird migration, an international volunteer project has begun called Operation RubyThroat. The project is designed primarily for K-12 teachers and their students in the countries of Central America and North America. You can find information on Operation RubyThroat at their web site: http://www.rubythroat.org/

Once in the United States, Ruby-throated Hummingbirds disperse widely. The breeding range extends from eastern Texas along the Gulf Coast to Florida and north in the east to Nova Scotia, New Brunswick and Labrador and west to Minnesota, then spreading westward in the Canadian prairie provinces, stopping just shy of British Columbia. Their breeding range is the largest of any hummingbird breeding in North America.

Hummingbirds are specialized to feed on nectar. A number of plants and hummingbirds have evolved mutualistic relationships. These plants produce sugar-rich nectar, which attracts hummingbirds. As the hummingbirds feed on the flower, pollen attaches to the hummingbird’s head and bill. When the hummingbird visits another flower, some of the pollen it is carried is transferred to the female part of the flower and fertilization is assured. Some plants therefore “pay” hummingbirds in nectar in return for pollination services.

One species that seems particularly adapted for pollination by Ruby-throated Hummingbirds is the trumpet creeper, a woodland vine. Studies have shown that Ruby-throated Hummingbirds deposited ten times as much pollen as other pollinators (bumblebees and honeybees).

Most long, tubular flowers are attractive to hummingbirds. Bee balm is particularly recommended. Of course, a hummingbird feeder is an easy way to attract hummingbirds as well. Choose a feeder with a wide mouth to make cleaning easy. You can buy so-called hummingbird food to dissolve in water. On the other hand, you can save some money and make your own. Just mix four parts of water to one part of table sugar and bring to a boil. When the sugar dissolves, cool and then fill your feeder. You can store the excess in your refrigerator for a couple of weeks.

Keep an eye on your feeder. Particularly in warmer weather, fungi grow in the feeder. You should wash your feeders regularly; easy to clean feeders will make this task a quick one.

Nest building in Ruby-throated Hummingbirds is done only by the female and takes between 6 and 9 days. The base of the nest is made of thistle and dandelion down. The base is saddled along a branch and is fastened with spider webs. The female stamps down the plant down to make a firm floor. White plant down and bud scales make up the side of the nest. The female uses a figure-8 motion to lace the plant material together. The outside of the nest is adorned with lichens, making a well-camouflaged nest.

Two eggs are laid and hatch 12-14 days later. The female does all the feeding of the young. The young are feed nectar at first with supplements of insects as they grow larger. The young fledge 18-20 days after hatching.

[Originally published on May 1, 2009]

2009-07-20T21:46:00.003-04:00

For the Birds - Earth Day

Wednesday is Earth Day. In today’s column, I will review a couple of major studies that have examined the impact of humans on bird populations. Both of these studies are based on citizen-science projects. Many of you will have contributed to the databases.

National Audubon scientists recently released the results of their study of the past 40 years of Audubon’s Christmas Bird Counts. The scientists analyzed the population changes of 305 bird species that occur widely in the winter in North America.

Of this total, 177 species have shifted their range northward. This northward shift is consistent with global warming. The average shift northward over the past 40 years is 35 miles for all 305 species, including those that do not show northward movements.

Of course, averages can mask more dramatic changes for some species. Boreal Chickadee, Purple Finch and Pine Siskin have retreated dramatically into Canada. The center of the ranges of these species has moved 211, 313 and 246 miles northward since 1968.

Species that rely on open water show pronounced shifts in their ranges as well. American Black Duck, Ring-necked Duck and Red-breasted Merganser show a northward shift of their ranges by 150 to 250 miles. These birds are able to winter further north because more open water is available in northern states and Canada.

Consider the increase in average number of the following species in Maine between 1968 and 2008: Mourning Dove (22.4 times increase), Red-bellied Woodpecker (5.5 times), Carolina Wren (5.0 times), Hermit Thrush (9.8 times) and White-throated Sparrow (2.8 times).

What’s the big deal you may ask? Don’t the birds just shift their ranges northward with no overall change in abundance?

Actually, this expansion of ranges toward the poles should give great concern. Consider a typical map of the world using a Mercator projection. On such a map, Greenland looks to be about the same size as Africa. In fact, Africa has 14 times the area of Greenland. A Mercator map distorts the area of land near the poles.

Instead, think about a globe of the earth with lines of longitude on it. Follow two adjacent lines of longitude from the equator to the North Pole, noting how the lines get closer and closer as you move from the equator.

By forcing birds northward, we are funneling them into smaller and smaller areas. Sooner or later, the birds will run out of habitat.

A second major report, The State of the Birds: United States of America, was recently published by a partnership of a dozen government and non-government organizations, including the Cornell Lab of Ornithology, the National Audubon Society and the U.S. Fish and Wildlife Service.

The report used three sources of data on bird population changes: the Christmas Bird Count, the Breeding Bird Survey and the Waterfowl Breeding Population and Habitat Survey.

The report is a balanced report, noting species that are declining and increasing. Environmental threats are thoroughly discussed and reasons for hope are covered as well. The report is mainly organized by general habitat, such as grasslands, arid lands, forests and wetlands.

Let’s consider forests as a representative habitat. The report tells us that North American forests harbor more than 300 species of breeding birds. Although some species are doing well, fully a third of these bird species are declining. The threats are familiar ones: unplanned, urban sprawl; unsustainable logging practices; intense wildfires caused by decades of fire suppression; impact of tree insects and tree diseases driven in part by climate change.

Examining eastern forests, the authors found that 25 species found exclusively in forests have declined in abundance by 25% in the past 40 years. Species of particular concern from eastern forests are Eastern Wood-Pewee, Wood Thrush, Blackpoll Warbler, Cape May Warbler, Pine Siskin, Evening Grosbeak and White-winged Crossbill.

To halt the declines, the authors suggest better planning of human development, green logging practices and doing all we can to slow the rate of carbon dioxide emissions to at least slow down the rate of global warming.

Space does not permit consideration of all the habitats covered in this thoughtful report. Copies are available for download at http://www.stateofthebirds.org/ I encourage you to read the document ; it will be well worth your time.

Finally, here are some suggestions for ways we can combat climate change. Visit http://www.birdsandclimate.org to sign the petition urging lawmakers to take steps to slow global warming. Determine your energy profile and carbon footprint. A number of carbon footprint calculators are available on-line. Become a locavore; buy locally grown produce and other food as often as you can. Plant more trees. Happy Earth Day!

[Originally published on April 18, 2009]

2009-04-27T21:57:00.007-04:00

Boreal Songbird Initiative - Please help!

The Boreal Songbird Initiative, along with other environmental groups like Bird Studies Canada, Nature Canada, the David Suzuki Foundation, among others created a petition called “Save our Boreal Birds” a little over a year ago. This petition will be sent to the Prime Minister of Canada and many provincial leaders, and asks that vital bird habitat be kept intact despite the fact that over 30% of the Boreal Forest has already been designated for development. Many migratory birds that travel through the US and other countries breed in the Boreal Forest to the north.

Sign the petition at SaveOurBorealBirds.org to protect Canada's Boreal Forest on behalf of the billions of birds that breed there!

2009-04-23T19:59:00.001-04:00

For the Birds - Common Grackle

Chances are good that Common Grackles have returned to your neighborhood by now. These large members of the blackbird family are one of the first of our migratory breeding birds to come back to Maine.

With a sleek, glossy black plumage and a yellow eye, the adult Common Grackle is a striking bird. The birds are about 12 inches long, including the long tail. It is not easy to tell males from females although the head of males, in favorable light, has a glossy purple head and breast. The female is usually slightly smaller than the male. In flight, grackles hold their tails in a V, like the keel of a boat.

Despite their sleek appearance, grackles will win no contests for the beauty of their songs. Both males and females sing the same harsh, squeaky song that some ornithologists interpret as "squ-eek", “readle-eak” or "scuda-leek". Some people think the song sounds like the opening of a gate with a rusty hinge. These birds also give a characteristic raspy "chack" call, often in flight.

Males sing more frequently than females and male song rates are highest early in the breeding season. Any individual sings a single song but there is a lot of variation among individuals. The songs therefore seem to be useful for individual identification.

Grackles are habitat generalists. Suburban areas, farmlands, swamps, and orchards are all suitable. Favoring more open habitats, grackles are typically not found in deep forests. Before European settlement and the clearing of forests, Common Grackles were uncommon birds in New England; now they are abundant. Aided by the planting of shelterbelts, Common Grackles have expanded their range westward across the Great Plains.

This species is highly gregarious; if you see one, you will probably see 10. Except for females incubating eggs, grackles roost together at night in noisy roosts, sometimes more than 100 birds in one roost.

Unlike some of our long-distance migrants, Common Grackles do not winter very far to the south of us. Some winter in southern New England with more wintering from Pennsylvania south.

Once the grackles return, keep an eye out for their courtship displays. The male will raise the feathers around his neck, drop his wings and sing his song for a prospective mate. This behavior is called the song spread.

Pairs form soon after the birds arrive. The female builds the nest, usually well above the ground in a conifer. The male guards the female throughout the nest construction process. Once the nest is complete, the female will perform a wing quivering display, a signal that she is ready to mate.

The male aggressively keeps other males away from his mate. A common threat display is sky pointing, when the male raises his bill vertically. This behavior is given by one male on the approach of another male. The display usually results in one of the males departing.

Common Grackles may nest alone but more often in colonies of ten or more pairs in tall trees, especially evergreens. Sometimes, nests are made in freshwater marshes, old building and even the lower parts of Osprey nests. The nest is made of twigs and grass stems. Most nests contain 5-6 eggs, which the female incubates for about 14 days before hatching. The newly hatched birds are ready for their first flight in 14-16 days. Unlike their dark parents, juveniles are dark brown with brown eyes.

Grackles have a broad diet, although insects are the most commonly captured prey. Grackles often search for food on the ground, walking slowly and deliberately. Occasionally, a bird may run and leap into the air to catch an insect. Grackles may probe in the ground for earthworms and will even take them from robins. Grackles will also search for food in trees. Besides insects, grackles are known to eat spiders, snakes, lizards and mice. The eggs and nestlings of other birds are not safe from grackles. Grackles are even reported to wade belly deep in freshwater for crayfishes, minnows, frogs and salamanders. Grackles will eat seeds including corn, acorns, and seeds of various weeds. In fact, Common Grackles are now a major agricultural pest, causing millions of dollars of damage to sprouting corn.

Some Common Grackles attain impressive ages. The oldest known Common Grackle was banded in Michigan and recaptured 20 years and 11 months later in Illinois! A Common Grackle in Minnesota lived to be at least 17 years old while a New Jersey bird lived to be at least 16 years and 1 month old. The average life span is likely much less than these extremes.

[Originally published on April 4, 2009]

2009-04-23T19:56:00.000-04:00

For the Birds - Geo-locating and Bird Migration

Keeping track of bird migration is a time-honored practice of naturalists dating back over 200 years. All of us delight at the arrival of the first Red-winged Blackbirds, Hermit Thrushes, or Yellow Warbler in the spring.

Until recently, our understanding of the timing of bird migration was based on populations of birds rather than individuals. We have to be able to follow individual birds to truly understand migration speeds and routes.

Bird banding has contributed some useful information. However, the chance of a bird bander capturing a bird banded earlier in the migration is pretty slim. The chance of capturing a banded bird immediately after its arrival is slimmer yet.

Outfitting birds with radio-tags that emit unique frequencies provides a way to track individual birds. The range of most radio-tags is limited to a couple of miles so this technology is more useful for tracking the movements of resident birds.

More recently, satellite transmitters have been developed that allow ornithologists to monitor the position of birds from their computers. For instance, researchers used satellite transmitters to track the migration of Short-tailed Albatrosses across the Pacific Ocean (http://www.wfu.edu/biology/albatross/shorttail/shorttail.htm).

Although radio and satellite transmitters have been miniaturized, they are still too large to place on most songbirds. A new technology, called geo-locating, promises to provide new insight into the pace and direction of small bird migration.

The geo-locaters were engineered by members of the British Antarctic Survey for use on larger birds and later miniaturized for use with songbirds. The songbird geo-locators are light (0.05 ounce). The device is essentially a small computer chip with a built-in clock and a short stalk. The geo-locator tracks light levels so that sunrise and sunset are recorded for each day. Knowing sunrise, sunset and day length allows the researchers to precisely determine the position of the bird every day. Essentially, the length of the day allows the latitude to be determined and the time of sunrise and sunset allows the longitude to be determined. Pretty neat!

The geo-locater is held on the rump of the bird with straps that wrap around the upper part of each leg.

The first results of this technique were recently published by a team of researchers led by Bridget Stutchbury from York University. The team captured 20 Purple Martins and 14 Wood Thrushes in the fall of 2007 in northern Pennsylvania. They were able to recapture five of the Wood Thrushes and two of the Purple Martins in the spring of 2008. The researchers downloaded the data from the geo-locater and were able to map the fall migration, winter movements and spring migration of each bird.

Even though only seven birds were recaptured, the results already cause us to rethink how migration occurs in songbirds. In the fall, the two Purple Martins flew south to the Yucatan Peninsula in five days (about 1500 miles in total). The martins stopped there for three to four weeks before continuing their migration to a wintering area to Brazil.

We know that spring migration is typically much faster than fall migration in most birds. There is an urgency about the spring migration as birds stream north to find mates and favorable territories. However, the speed of the Purple Martin spring migration was more rapid than suspected. One of the tagged martins flew from the Amazon basin back to Pennsylvania in only 13 days, traversing over 3000 miles. Four of those days were spent on stopover. Prior to this work, ornithologists believed that a nightly flight of about 100 miles was about the maximum distance most songbirds can manage.

Four of the five Wood Thrushes migrated to the southeastern United States, spending one to two weeks there before flying across the Gulf of Mexico to the Yucatan Peninsula. The birds wintered in Honduras and Nicaragua. Most of the thrushes returned to Pennsylvania in 13 to 15 days, again crossing the Gulf of Mexico. One thrush took the landward route, avoiding the Gulf crossing.

[Originally published on March 21, 2009]

2009-04-23T19:54:00.004-04:00

For the Birds - Costa Rica Trip - Part II

This column is the second of two presenting some birding highlights of my visit to Costa Rica in January.

We left the rainforest reserve at La Selva bound for the Ecolodge at San Luis just west of the Continental Divide. The trade winds were unrelenting there, making birding by ear difficult and keeping the birds down.

One of the highlights was a pair of Emerald Toucanets, a mostly green small toucan. A pair of male Black-breasted Wood-Quail were fighting with other, oblivious to the ten people watching them.

In local pastures, I had nice views of Yellow-faced Grassquits, White-eared Ground-sparrows and a Social Flycatcher. Raucous Brown Jays were extremely common.

A local family maintained a bird feeder, stocked with fruit, that attracted Blue-gray Tanagers, Passerini’s Tanagers, Crimson-collared Tanagers (spectacular!), Buff-throated Saltators and Yellow-throated Euphonias. Old friends were seen in the trees: Black-and-White Warbler, Chestnut-sided Warbler and Baltimore Oriole.

We hired a taxi to take us from San Luis to the Monteverde Cloud Forest Reserve for a daylong adventure. This site was only 500 meters higher than San Luis but was truly a different world. Typical weather is misting rain with low-lying clouds. Epiphytes are everywhere on the trees.

The most sought-after bird at Monteverde is the Resplendent Quetzal, a specialist on avocados. We hired three guides to lead our class on a morning walk. The guides knew of an avocado tree where a pair of quetzals were feeding. With patience, we got a good look at a female through a spotting scope. Later in the morning, a male appeared briefly no more than 50 feet way.

The Resplendent Quetzal, a member of the trogon family, is often touted as the most beautiful bird in the world. I find it hard to argue. The male has a brilliant green head, throat and back and a scarlet red breast and belly. The tail is white with four long green uppertail coverts that extend well beyond the tail. The female is similar with more muted colors. Females lack the long tail coverts of the males.

This species is the national bird of Guatemala. Quetzals were revered by the Aztecs, Mayas and other Mesoamerican peoples.
Other avian highlights at Monteverde included a Black Guan, a roosting Mottled Owl, and Ochraceous Wood-Wrens. Several fearless Slate-throated Redstarts flitted about us for a while. These mostly yellow sprites are called candelitos (little candles) by Costa Ricans because their frenetic movements suggest flickering.

We saw seven hummingbird species including the large Green Hermit and Violet Sabrewing. Stripe-tailed Hummingbirds were seen as well. These hummers are nectar robbers. Many flowers with long tubular flowers rely on hummingbirds for pollination. The flowers essentially reward the hummingbirds with nectar for acting as pollinators. Striped-tailed Hummingbirds have relatively short bills. To reach the nectar of tubular flowers, the birds pierce the base of the flower to get the nectar but do not get a shower of pollen on them like other hummingbirds do.

Bananaquits and Common Bush Tanagers were nice finds as well.
Our last stop was the tropical dry forest of Santa Rosa National Park. This park is in the northwest corner of Costa Rica. We were there during the dry season when a strong rain shadow effect of the mountains to the east makes rain a rare event for half of the year. It was very hot during our stay.

Because of the dryness, some of the trees lose their leaves. The forest floor had a significant layer of dead leaves, similar to our northern broad-leaf forests.

The most conspicuous birds were White-breasted Magpie-Jays with their curly feathers on the top of the head. A Roadside Hawk, a buteo hawk, was regularly seen. Three species of parrots were heard and sometimes seen: White-fronted Parrot, Yellow-naped Parrot and Orange-fronted Parakeet.

Hoffman’s Woodpecker was the most common woodpecker. Flycatchers were conspicuous but less diverse than at La Selva. Most were Great-crested Flycatchers, Dusky-capped Flycatchers and Streaked Flycatchers
The resident Rufous-capped Warblers were joined by Yellow Warblers.

The pigeons were represented by three common species: Inca Dove, White-tipped Dove, and White-winged Pigeon. Thicket Tinamous called from sights unseen. Lots of Ruby-throated Hummingbirds were present. Other neat birds were Barred Antshrikes, Rufous-naped Wrens and Scrub Euphonias. We found a sleeping Northern Potoo, doing a superb imitation of a broken tree limb.
Santa Rosa is a great place to see monkeys. We had several extended views of white-faced capuchin monkeys and howler monkeys.

A trip to the Pacific Ocean (Playa Naranjo) yielded Brown Pelicans, Magnificent Frigatebirds and lots of Brown Boobies. I never got used to the lack of gulls.

[Originally published on March 7, 2009]

2009-04-23T19:52:00.005-04:00

For the Birds - Costa Rica Trip - Part I

My colleague Judy Stone and I spent most of January in Costa Rica teaching a Colby biology class. The focus of our course was plants of the tropics but I had time to enjoy some wonderful birding while we were there. I’ll devote this column and the next to some of the birding highlights of our visit.

Costa Rica is a small country, roughly the size of West Virginia. Within that small area, however, the range of climate, topography and vegetation is great. It is no wonder that 875 species of birds occur in Costa Rica. The United States and Canada combined scarcely exceed that number of species.

We spent our first week in Costa Rica at the La Selva Biological Station near the town of Puerto Viejo, north of San Jose. This site, at an elevation, of about 500 feet is lowland rainforest. The trade winds blow across Costa Rica from the east, bringing moisture-laden air off the Caribbean onto shore. As the air rises, it cools and drops the moisture as rain. We were at La Selva during the dry season but, as we learned, La Selva has a rainy season and a rainier season. We were lucky though as most of the rain fell during the evening hours.

The first bird I saw at La Selva looked like a small warbler, flitting near the top of a large tree. It was a warbler indeed but not the tropical species I was expecting. It was a Chestnut-sided Warbler, one of the most common nesting warblers in Maine. I noted a number of other birds that breed here in Maine enjoying the Costa Rican warmth: Turkey Vulture, Tennessee Warbler, Louisiana Waterthrush, Baltimore Oriole and Red-winged Blackbird.

We were assigned rooms in an older building called the River Station, overlooking the Puerto Viejo River. A pair of Crested Guans, chicken-like birds with bright red wattles, were feeding just above the trail on fruits. A Blue-black Grosbeak was in an adjacent tree.

Montezuma’s Oropendolas were the most conspicuous birds at La Selva. These members of the blackbird family are large and loud. Males are about 20 inches long, females five inches shorter. Most black, Montezuma’s Oropendolas have bright yellow tails and conspicuous white markings on the side of the head. Females were just beginning to build their pendant nests in palm trees. The nests are similar to those of a Baltimore Oriole but much longer. Males were displaying to females. The display is memorable. The male perches on a branch and gives a loud, liquid song. At a distance, the song is quite pleasing but metallic screeches can be heard when close to a male. As the male finishes his song, he performs a deep bow, rotating his body a full half turn, showing off his bright yellow tail. Despite the bravura performances, the females seemed unimpressed.

Mornings at La Selva were almost magical. Great Tinamous gave their wavering, flute-like call from deep in the jungle. Rufous Motmots gave their lovely hoot-hoot-hoot calls that reminded me of notes from a wooden percussion instrument. As dawn approached, the glorious songs of White-breasted Wood Wrens, Striped-breasted Wrens and Black-throated Wrens filled the air.

Parrots were vocal but usually difficult to see in the tops of trees. With patience, we got good looks at Mealy Parrots, Red-lored Parrots, Brown-hooded Parrots and White-crowned Parrots. The highlight though was eight fly-over Great Green Macaws. Only about 200 individuals are left in Costa Rica.

Birds at La Selva often move in large, fast-moving mixed flocks. One memorable flock had Palm Tanagers, Passerini’s Tanagers, Dusky-faced Tanagers, Blue-gray Tanagers and Golden-hooded Tanagers. Within five minutes, the flock had moved on.

I enjoyed seeing birds in families that were new to me. A Rufous-tailed Jacamar, related to the woodpeckers, looked alike an overgrown hummingbird with its long thin bill. A pair of Pied Puffbirds provided us with great views; these birds are also related to the woodpeckers. We saw Northern Barred Woodcreepers and Streak-headed Woodcreepers. Woodcreepers are perching birds that behave much like woodpeckers. A Great Antshrike gave me a brief look before diving back into its preferred dense undergrowth habitat.

Other memorable sightings included a male Green Honeycreeper with fluorescent green plumage, Olive-backed Euphonias, a Green Kingfisher and a ton of flycatcher species including Boat-billed Flycatcher, White-ringed Flycatcher, Common Tody-Flycatcher, Mistletoe Tyrannulet, Rufous Mourner, Bright-rumped Attila and Long-tailed Tyrant. Chestnut-colored Woodpeckers, Black-cheeked Woodpeckers and Pale-billed Woodpeckers were striking birds as well.

[Originally published on February 21, 2009]

2009-02-24T09:29:00.002-05:00

For the Birds: Maine Christmas Bird Count review

The Maine Christmas Bird Counts conducted from Dec. 14 to Jan. 5 yielded particularly high numbers of sightings of common species, of irruptive species like Bohemian waxwings – and of the rarities whose discovery makes a Christmas Count so exciting.

Perhaps the most remarkable species in this winter's count are the pine siskin and white-winged crossbill. Both are irruptive species, visiting Maine in the winter when their food supplies are depleted to our north.

The pine siskin irruption this year has been nothing short of spectacular. These wanderers have been absent from many Maine Christmas Bird Counts over the past decade. Consider the sightings from this year's counts: 92 in Augusta, 297 in the Belfast area, 361 in Waterville and 350 in Biddeford-Kennebunkport.

Interestingly, pine siskin numbers were quite low on counts dominated by spruce-fir forest that normally have the highest numbers of these sprites. The Misery township (just south of Jackman) and the Schoodic Peninsula counts yielded only four.

The number of pine siskins sighted in Maine has continued to increase over the past month. Peter Vickery of Richmond saw a Eurasian siskin among the pine siskins at his feeder. Get your niger seeds out there for the siskins!

White-winged crossbills have also staged an impressive invasion this winter. Many counts shattered their previous records for this species. The Portland counters found 672 white-winged crossbills – the previous record was eight. Similarly, the Waterville count produced 216, dwarfing the previous high of five.

The Misery count usually produces the most white-winged crossbill sightings, but this year none were found there. I saw lots of white-winged crossbills this summer in coastal Washington County, but none were found in the Moose Island-Jonesport count. The crossbills seemed to have pushed south of their typical winter range.

Common redpolls generally show a biennial pattern of irruption into Maine. Last year, these birds staged a major invasion into the state. One therefore expects this winter to have a light flight of these finches.

Although a number of counts recorded redpolls, numbers were usually low except for the 147 in the Augusta count.

As is typical, Bohemian waxwings had a patchy distribution in Maine over the count period. The Bangor-Bucksport count produced 1,794 Bohemians (and 792 cedar waxwings) and 670 were in the Farmington count. Elsewhere, Bohemians were mostly absent, or present in single digits.

Red-bellied woodpeckers staged a strong invasion into Maine this fall, and a number of them were found by Christmas count participants. The Portland count had 15 red-bellies, eclipsing the former record of four. Six were found in Bangor-Bucksport, eight were found in Augusta and 17 in Biddeford-Kennebunkport.

Blue jays show an intriguing winter movement called partial migration. Some blue jays spend the entire year in Maine, while a proportion will migrate to more southerly areas, particularly if food supplies are low. Blue jays depend heavily on acorns during the winter. The acorn crop must have been more than adequate this year as higher than normal numbers of blue jays were counted in many Maine counts. In Augusta, the 674 blue jays shattered the previous high count of 61.

Maine Christmas Counts usually yield a number of lingering birds that will likely be forced to migrate or perish before the winter is over. Great blue herons are a case in point. Hardy herons showed up on the Biddeford-Kennebunkport, Portland, Thomaston-Rockland, Waterville, Augusta, Moose Island-Jonesport and the Schoodic Peninsula counts.

Other lingering species included a common tern, Eastern bluebirds, hermit thrushes, Carolina wrens, yellow-rumped warblers, a yellow-breasted chat, a summer tanager, Eastern towhees, fox sparrows, a white-crowned sparrow, a grasshopper sparrow and a Baltimore oriole.

Not surprisingly, most of these showed up on counts in the southern part of the state, especially along the coast where the weather is not quite as severe as in northern and inland areas.

As usual, the Portland count recorded the highest number of species in the state. The 114 species tallied represent a new record for the count. Four species were found that had never been recorded on that count: ruddy turnstone, blue-headed vireo, clay-colored sparrow and red crossbill.

As expected, the Misery count yielded the lowest number of species in this challenging environment. Fifteen species were counted, including gray jays, pine grosbeaks and red crossbills.

To see the complete totals for the Maine Christmas Bird Counts, visit www.audubon.org/Bird/cbc

[Originally published on February 7, 2009]

2009-02-24T09:27:00.003-05:00

For the Birds: South Carolina trip II

This column is the second of two on the birds seen on a South Carolina coastal visit in late December. This column will focus on a trip to a forest tract near the Santee River north of McClellanville.

Although development pressures along the South Carolina coast continue to increase, significant tracts of land are protected. Much of the biologically rich area along the coastal Santee River is protected by holdings of the Francis Marion National Forest and by Nature Conservancy holdings.

We had the chance to explore a tract of preserved land north of McClellanville on December 31 on a warm sunny day.

We began with

a walk along a boardwalk through a bald cypress swamp. These conifers have trunks that are swollen at their bases. Each tree puts up a number of knees, short woody growths that extend a few feet above the black water of the swamp. Water tupelos were also common trees, also having buttressed trunks. The surface of the water was a green, unbroken carpet of duckweed, a small aquatic floating plant. You may have seen duckweed in Maine.

The birds here were few, mostly Yellow-rumped Warblers. A small impoundment at the end of the boardwalk had no ducks. We did see a large number of Double-crested Cormorants and a lone Anhinga flying toward an adjacent impoundment. We backtracked down the boardwalk and walked toward the second impoundment. On the way, a Red-shouldered Hawk called repeatedly overhead.

At the second impoundment, we found a number of cormorants. I was glad I had lugged my spotting scope along because we enjoyed leisurely views of two Belted Kingfishers perched on the bank in perfect light.

Lots of Hooded Mergansers were on the water along with a Pied-billed Grebe. A Great Blue Heron and a Great Egret were patrolling the shallows for incautious fish. Hundreds of Tree Swallows were hawking unseen insects above the water.

Walking around the impoundment along a woodland path, we heard the chip notes of Yellow-rumped Warblers and Ruby-crowned Kinglets in the upper reaches of the live oaks. I began to pish to try to draw the birds closer. (In case you have never heard a birder pish, the birder rapidly repeats “psssh” to mimic a general alarm call. Landbirds will often come close to investigate and possibly mob the intruder.)

Before long, 60 birds were close by. Ruby-crowned Kinglets were the most common although we picked out a Golden-crowned Kinglet, several titmice, a White-breasted Nuthatch and Carolina Chickadees. At least one Pine Warbler was among the many yellow-rumps. Quite a spectacle.

Continuing along the path, we came to a sluice that controls the level of the water in the impoundment. Forty feet away, two Wood Storks were perched on a tree adjacent to the outflow stream. They sat calmly while we enjoyed watching them through the spotting scope.

A Brown Pelican was on the water in the impoundment. Brown Pelicans generally occur in saltwater habitats but occasionally venture into freshwater habitats. A Pied-billed Grebe could be in the same scope view as the pelican.

It is hard to go for very long in coastal South Carolina without seeing vultures. A number of Turkey Vultures hovered during most of our walk. Black Vultures were present as well although in lower numbers. Telling the two species apart is flight is straightforward. Turkey Vultures hold their wings in a shallow V while soaring while Black Vultures have their wings extended horizontally like an eagle or Red-tailed Hawk. The tail of a Turkey Vulture is long while that of Black Vultures is noticeably short. When a Black Vulture spreads its tail, the tail seems to disappear into the hind margin of the long wings. Finally, Black Vultures have a large white area on the tip of the underwing. Seen in the right light, these white areas glisten against the black background.

We were pleased to see some butterflies on the wing. A Cloudless Sulphur, a larger relative of the Clouded Sulphur that is so common in Maine, flitted by. We saw several Red Admirals, perched on the ground. The butterflies were courting mates and occasionally flew up for a brief dogfight with another admiral. Red Admirals feed on sap and decaying matter so the rarity of flowers posed no problem for them. We saw a few Green Darners, a large dragonfly with a striking green head and blue body.

On the way back to the parking lot, we walked through an open field with scattered trees. This area looked like perfect habitat for Eastern Bluebirds and so it was. At least six were present. Extended views through the spotting scope of two males perched on the outer branches of a live oak provided a fitting end to a wonderful trip.

[Originally published on January 24, 2008]

2009-02-24T09:24:00.003-05:00

For the Birds: South Carolina trip I

My wife and I took a holiday trip to North and South Carolina in late December. We spent five delightful days on the South Carolina coast with friends in McClellanville, South Carolina. The birding and the weather were delightful.

The maritime forest of the Carolinas is dominated by live oaks. These evergreen oaks rarely exceed fifty feet in height but have many large horizontal branches that extend out for tens of feet and then grow upward to the canopy. Foresters report that some live oaks can occupy a full acre! The trunks of these trees are large with diameters regularly exceeding six feet. The largest live oak known had a diameter of 11.5 feet.

The small fishing town of McClellanville is dominated by live oaks. The few roads through the village seem to be tunnels through these great trees.
The live oaks provide habitat for many birds. Walks through the village turned up Carolina Chickadees, Tufted Titmice, Carolina Wrens and tons of woodpeckers, the most common being Northern Flickers, Red-bellied Woodpeckers and Downy Woodpeckers.

Yellow-rumped Warblers are common wintering birds in this part of the world. Most warblers rely on insects gleaned from leaves for their food year-round. Most of the warblers that nest in North America are now on Caribbean islands or in Central and South America. The Yellow-rumped Warblers are more flexible in their diet and switch to fruit eating during the winter. These warblers depend on the fruits of the abundant wax myrtle bushes found along the coast of the southeastern United States. Of course, they will feed on insects if they can find them. But their ability to switch to fruit eating means they do not have to make the arduous migration to tropical climates to pass the winter.

My ears told me I was not in Maine when I walked out of the house on morning to hear the energetic fee-bee of an Eastern Phoebe. Like the Yellow-rumped Warblers, the phoebes will switch to small fruits when the flying insects they depend on are not easy to find.
An unusual sound in the village was the three-note song of a recent colonist, the European Collared Dove. The song is a set of three coos, with the second one longer and stronger. It has the same cadence as the word “united”.

The European Collared Doves are native to southeastern Europe. These birds were introduced in the Bahamas in 1970 and spread to Florida by 1982. The species has expanded in the United States reaching Veracruz, Mexico, the Great Lake states and even British Columbia. I know of a single record from Maine on Monhegan Island. The largest densities of these birds are in the Gulf coast states.

Some ornithologists think the Collared Doves are taking the place of the extinct Passenger Pigeon that was so abundant in the United States until the latter part of the 1800’s.
It’s too early to tell what effect if any the Collared Doves are having on our native birds. The expansion of their population seems slower than the explosive invasion of the birds into western Europe fifty years ago.

Our friends in McClellanville have s small skiff so we were delighted to take a bird excursion through the maze of streams that divide the huge salt marshes of the area. Buffleheads, Hooded Mergansers and Red-breasted Mergansers were the most common ducks. Occasionally, a Bottle-nosed Dolphin would break the surface of the water near the boat. Boat-tailed Grackles were common in the salt marsh.

Two Bald Eagles were a real treat. A Red-tailed Hawk perched atop a navigation pole and a Merlin streaked by at breakneck speed.

Brown Pelicans were common. I still marvel at the ability of these birds to glide effortlessly just above the water. We also saw a flock of 40 White Pelicans, regular wintering boards along this portion of the coast. Unlike the Brown Pelicans that dive to capture fish, White Pelicans are social hunters. A group of White Pelicans will form a semicircle just offshore and swim toward the shore, driving any small fish into the center of the semicircle where they can be captured by simply bobbing underwater. White Pelicans do not dive.

The exposed intertidal flats had a nice mixture of shorebirds. Sanderlings, Dunlin, Short-billed Dowitchers and Piping Plovers were seen. It was hard to miss the American Oystercatchers with their raucous calls and their striking appearance (black and white plumage and long red bills).

Double-crested Cormorants, Common Loons, a single Red-throated Loon, Northern Gannets and Belted Kingfishers made it to our list as well.

In the next column, I’ll describe a wonderful trip to the coastal forest of the Santee River.

[Originally published on January 10, 2009]

2009-02-24T08:51:00.002-05:00

For the Birds: American Crows

Have you been seeing large numbers of American Crows converging from all directions shortly before dusk? Shoppers in Waterville and Augusta are often surprised as nocturnal roosts of crows start to build close to shopping malls. The roost in Waterville must number in the thousands of crows.

It often takes a spectacular aggregation of crows for us to even notice them. American Crows are common, seen every day by anyone with an eye for nature. We take crows for granted. Yet, these birds have some fascinating behaviors and traits that reward a careful look.

Let’s start with their roosting behavior. Night-time roosts may contain fewer than 100 birds to tens or hundreds of thousands. One well-known roost in Oklahoma contains around two million crows!

The reasons for roosting are unclear. A large flock of birds is certainly more vigilant against predators. A large bird of prey has little chance of sneaking up on a roost of crows.

A controversial explanation for roosting in birds is to provide a way to exchange information about food locations. However, no one has convincingly shown that crows exchange information at their roosts.

Roosts often occur, like the ones in Waterville and Augusta, in urban areas. We know that the minimum temperatures in the vicinity of human developments (houses, roads, parking lots) can be as much as ten degrees warmer than in undeveloped areas. On a cold Maine night, every degree of warmth can help birds make it through the night.

In the morning, crows leave their roosts but usually do not leave alone. Crows have a stable family structure. Groups of birds consisting of a mated pair (crows mate for life) as well as their offspring from several different years leave together. This group defends a territory against other flocks of crows.

American Crows are widely distributed in North America. They are found throughout the United States except for portions of southeastern California, western Arizona, and most of Utah and Nevada. American Crows are found broadly across the southern half of Canada.

American Crows occur in a variety of habitats but are most common in open woodland areas. With the clearing of eastern forests by European colonists, American Crows increased in abundance after European colonization. Regarded as agricultural pests, American Crows were persecuted for most of the 19th century and the early part of the 20th century. The crows found that towns and cities provided a refuge from hunters and began to use urban and suburban habitats. With their broad diet, American Crows have little trouble finding food to eat in urban and suburban environments.

Like most members of the family Corvidae (jays, crows and ravens), American Crows have a broad diet. One can aptly describe them as omnivorous because their diet includes terrestrial and marine invertebrates, amphibians, reptiles, small birds and mammals, the eggs, nestlings and fledglings of birds, seed crops of various types, fruit, carrion and the French fries and other food that humans discard.

Over 200 species of birds share the behavior of cooperative breeding. Offspring from an earlier brood or grandparents, aunts, uncles or cousins may assist a breeding pair in raising their young. Many of the best studied species that display cooperative breeding have exotic names to North American birders: Superb Starling, Superb Fairy-wren and Gray-crowned Babbler, to name a few. Yet, we have a cooperative breeder right in our midst. American Crows show this intriguing nesting behavior.

The nature of cooperative breeding varies across North America. In Massachusetts, 94% of American Crow pairs had helpers with an average of 4.2 birds helping raise a clutch of eggs. In Florida, the cooperating group was even larger with 7.2 birds on average helping to raise the young.

Young birds may help their parents for up to six years before they become parents for the first time. Helpers make themselves useful in a number of ways. Helpers may help with nest building, help keep the nest clean, feed the incubating female and the nestlings and guard the eggs and nestlings when the parents are away from the nest.

The vast majority of helpers are related to the young that they help raise to fledging. The helpers therefore share genes with the current brood. So by helping to raise brothers or sisters, they are perpetuating some of the own genes without reproducing themselves.

We are use to hearing the caw of American Crows but their vocal repertoire is actually quite large. Many variants of the caw exist and they can also produce other sounds including screeches, barks, rattles, grating sounds and clicks. Carefully study of the variety of crow vocalizations is amazing.

[Originally published on December 27. 2008]

2009-02-24T08:48:00.003-05:00

For the Birds: Waxwings

With their silky sleek plumage, bold black eye stripes, black chins and prominent crests, waxwings are one of our most handsome birds. We have two species of waxwings in Maine, the Cedar Waxwing and the Bohemian Waxwing. Both species can be currently found in Maine.

There are just three species of waxwings in the world. The Cedar Waxwing is restricted to North America. The Bohemian Waxwing is found broadly across the boreal habitat of the northern hemisphere. Bohemians occur in North American and across the breadth of northern Eurasia. The third species, the Japanese Waxwing, This species nests in southeastern Russia and adjacent China and winters mainly in eastern China, Korea and Japan.

Waxwings are so named because of the bright red, teardrops of waxy material found on some of the wing feathers and to a lesser extent on the tail feathers. The function of these wax drops is not known.

The Cedar Waxwing is a common and widespread breeding bird in Maine. During the summer, they flit from tree to tree, giving their characteristic, buzzy zirr-r-r calls. During the summer, Cedar Waxwings eat flower petals, sap and insects as well as small fruits. During the winter, fruits make up most of the diet. The fruits of mountain ash are high on their list of preferred fruits in the winter although rose hips, juniper berries, hawthorn fruits and many ornamental berries are taken as well.

Cedar Waxwings are often hard to find in Maine in the winter. Most of our breeding Cedar Waxwings migrate to more southern states for the winter, often flocking in groups of hundreds of birds. A nice flock is gracing us with their present on the Colby campus now but will likely move south before the winter is over.

The Bohemian Waxwing is an erratic winter visitor to Maine. Befitting their name, these birds are known for their nomadic wandering in the winter in search of fruit. Bohemian Waxwings nest in western North America, mostly in Canada and Alaska. When fruit crops in western North America are poor, these birds move east searching for dependable food supplies. In some years, Bohemian Waxwings are absent; in other years, they may be abundant. Huge flocks may locate a good food supply and then depart as soon as all the fruit is eaten.

Flocks of Bohemian Waxwings are generally much larger than flocks of Cedar Waxwings. More than 3000 birds have been found in one Bohemian flock; Cedar Waxwings usually occur in flocks of fewer than 100 birds.

“Drunk drivers” can be found in groups of waxwings. Sometimes, waxwings will feed on fermented fruit. The alcohol contained in the fermented fruit intoxicates the waxwings, which then have difficulty flying and even standing when they overindulge.

The gut of waxwings is well adapted for fruit eating. The bill and esophagus are both broad enough to allow fruits to swallowed whole. Fruit eating poses a physiological demand on waxwings. Winter fruit tends to be high in sugars but low in water and nutrient content. The passage of this food through the gut upsets the water balance of the bird, forcing the bird to drink often.

The low nutritive value of waxwings’ food means these birds must eat a lot of fruit to meet their daily dietary needs. The result is a rapid passage of material through the birds. The next time you encounter a flock of feeding waxwings, listen for the near constant rain of bird droppings falling on the ground.

How can you tell the two species of waxwings apart? Bohemian Waxwings are slightly larger and grayer than Cedar Waxwings. Sometimes, both species occur in the same flocks so a direct comparison is possible. However, there are better ways to distinguish the two species.

The Cedar Waxwing has wings without the yellow spots that are found in Bohemian Waxwing wings. The belly of Cedar is yellowish while that of Bohemian is grayish. However, the best mark is to look at the color of the undertail coverts. These are the short feathers at the base of the underside of the tail. In the Cedar Waxwing, these feathers are white. In the Bohemian Waxwing, they are a bright cinnamon color. It is easy to pick out this difference at a great distance, making the color of the undertail coverts the most useful identification feature.

Waxwings are often described as birds of the woods but that claim is a bit misleading. Waxwings are generally found in open woodlands, on the edges of tracts of forest or in regenerating forests where their favored fruits are abundant.

[Originally published on December 13, 2008]

2009-02-24T08:44:00.002-05:00

For the Birds: Bird Feeding Effects - Part II

Gillian Robb, an Irish ornithologist, and several of her colleagues have recently published a review of avian responses to supplemental feeding in the journal Frontiers in Ecology and the Environment. I discussed some of their points in the last column and will continue that discussion in today’s column.

Providing supplemental food to breeding females may allow them to spend less time looking for food and more time incubating the eggs or dependent young. Such an effect has been clearly shown in a study of Australian reed warblers and is likely a general phenomenon.

Given extra food, parents can either spend less time foraging for food to give their nestlings or use their extra time to find even more natural food for their young. In most species studied, parents simply spend less time looking for food rather than ambitiously trying to give their young even more food.

Chicks given supplemental food were much more likely to fledge than chicks without access to extra food in nearly two-thirds of the studies Robb reviewed. Black-legged Kittiwakes show one of the most striking effects. Adults fed supplemental food over two years, fed in turn to their chicks, fledged twice as many chicks in their first year and three times as many in the second year as kittiwakes that were not given extra food.

Given the difficulty of finding food for many birds, it is not surprising that supplemental feeding can alter the behavior of birds. Varied Tits (a chickadee relative) reduced their participation in winter mixed-species flocks when given extra food. Mixed-species flocks form when food is scarce and patchy.

The authors cite some of my research on Black-capped Chickadees in the North Woods of Maine. By providing supplemental food, I found that winter territorial boundaries break down. As many as 10 different winter flocks used the same feeders over the course of a single day.

Supplementary feeding may affect bird reproductive behavior. When House Sparrows were provided with extra food, the males stayed closer to their nests. Females cheating on their mates by mating with other males decreased because of the increased presence of the male.

Providing food to birds can alter the distribution of birds over large geographic areas. The northward expansion of Northern Cardinals may have resulted, at least in part, from backyard bird feeding. In Finland, ornithologists strongly suggest that backyard feeding explains a tendency of birds to overwinter in Finland rather than migrate south.

A contentious topic related to bird feeding concerns the degree to which birds become dependent on our handouts. In Finland, Great Tits feed most of the time from feeders and ornithologists suggest that these birds are so dependent on supplemental food that they could not survive without the freebies. So, feeding stations can be seen as ecological traps.

However, a study in Wisconsin with Black-capped Chickadees failed to find such feeder dependency. A population of chickadees that had been fed for 25 years was deprived of extra food in one winter. Those birds survived at the same rate as other chickadee populations close by that had never been given supplemental food.

Winter feeding can increase the density of resident birds in an area. These birds may stay in the area to nest during the summer, inflating the number of breeding birds. Jays and crows living close to humans take up to 75% of their food from human handouts. The local increase in these birds poses a threat to other songbirds because jays and crows are efficient egg predators.

Bird feeding can have indirect impacts as well. The gathering of large numbers of birds at one place increases the likelihood of the spread of diseases. The bacteria Mycoplasma and Salmonella are particular threats. The increased risk of disease at bird feeders in the United Kingdom is so high that the Garden Bird Health Initiative was begun, which prescribes bird feeding practices to lower the risk.

Some people that feed the birds are concerned that the high concentration of birds attracts birds of prey like Sharp-shinned Hawks or Cooper’s Hawks. Happily, research has shown that birds frequenting feeders are not more likely to be killed by predators. Large groups of birds are vigilant; the approach of a predatory bird or mammal is usually detected by the many watchful birds at a feeder.

We still have much to learn about the effects of bird feeding. Most studies have been conducted at a single feeder rather than at widely dispersed feeders, reflecting the distribution of households that feed the birds.

Should we feed the birds? To date, we believe the benefits exceed the risks. So, keep those feeders filled!

[Originally published on November 28, 2008]

2009-02-24T08:39:00.002-05:00

For the Birds: Bird Feeding Effects - Part I

Feeding the birds is an activity that has increased greatly in the past 40 years. In the United States, 43% of households maintain bird feeders. In the United Kingdom, bird feeding is even more popular; 75% of households there feed the birds.

Homeowners in the United States and the United Kingdom purchase 500,000 tons of birdseed each year. This bounty is enough to support 300 million chickadees living on nothing else. In short, bird feeding represents a major subsidy to many species of birds.

We know that food often limits bird populations so bird feeding may have positive benefits for birds. However, we know surprisingly little about the effects of bird feeding, particularly on larger geographic scales. Most of the work that has been done, including some of my own, has been concerned with local effects.

Gillian Robb, an Irish ornithologist, and several of her colleagues have recently published a review of avian responses to supplemental feeding in the journal Frontiers in Ecology and the Environment. Today’s column is the first of two in which I will summarize the major points of the article.

The energetic costs of reproduction are huge for birds. Favorable times for nesting are often brief in birds so an early start may be beneficial for breeding birds. In 34 of 59 studies reviewed by Robb, bird feeding resulted in earlier nesting. In most cases the shift was less than a week but in some a shift was as long as a month earlier.

Unfortunately, earlier nesting can sometimes result in negative impacts. Birds given supplemental food may begin nesting before their natural food supply becomes abundant enough to provide enough nutrition for their nestlings. As an example, chickadee adults do well feeding on sunflower seeds but their nestlings need caterpillars and other sources of animal protein to allow the nestlings to grow and thrive.

Food supplementation can affect the quantity and quality of eggs laid by female birds. In 44 studies reviewed by Robb, 28 presented evidence that bird feeding increased the number of eggs laid.

As an alternative (or as a second effect), a female bird with access to supplemental food may increase the quality of her eggs by laying larger eggs. Larger eggs cool more slowly than smaller eggs when the adults are off the nest; larger eggs have a greater chance of hatching than smaller eggs.

Florida Scrub Jays given high-fat, high-protein food laid eggs with more water and protein in them. Some popular bird foods may be a rich source of macronutrients. For instance, peanuts are high in vitamin E. This vitamin E can be passed into the eggs by a female bird. These enhanced nutrient levels result in better immune responses by nestlings to the threats of disease.

Supplemental food may increase the chances that a pair of birds can have two clutches during a single breeding season. For instance, when Black-throated Blue Warbler females were given food after their first clutch, all of the females started a second clutch compared to only 50% of the females that were not given supplemental food. This effect even carried on into the next year. Two-thirds of the females given extra food in one year had two broods the following year compared to none for the females not given extra food in the prior year. This striking result shows the dramatic and long-lasting effect that bird feeding can have on bird reproductive success.

In humans, the sex of a baby is determined by the sex chromosomes. Females have two X chromosomes whereas males have a single X chromosome and a much smaller Y chromosome. In birds, sex is determined in the opposite way: males have two similar chromosomes (called Z chromosomes) while females have a Z chromosome and a smaller W chromosome.

Birds differ from mammals in that female birds have the ability to control the sex ratio of their young. The kakapo, a flightless parrot found only in New Zealand, provides an interesting example. The kakapo is an endangered species whose population declined to as few as 70 individuals.

Wildlife biologists decided to try to increase the nesting success by giving the female kakapos supplementary food. Unfortunately, the kakapo females that received the extra nutrition responded by producing more male offspring! So the wildlife biologists had to lower the amount of extra food provided to strike a happy medium: enough to increase the nesting success of the female but not so high as to cause the females to produce mostly male offspring.

Stay tuned until the next column for more information on the impacts of feeding the birds.

[Originally published on November 14, 2008]

2008-11-23T17:37:00.002-05:00

For the Birds: Recent Ornithological Research

In today’s column, I will recap some of the articles that have been published in major North American ornithology journals this year. The emphasis will be on birds that occur in Maine.

All of us are thrilled when Evening Grosbeaks come to visit at our bird feeders. For readers who have been birding for at least 20 years, you will no doubt remember times when Evening Grosbeaks descended in large flocks, quickly devastating the sunflower seeds in your feeder. Sadly, these large flocks seem a distant memory.

In a recent article in the Condor, David Bonter and Michael Harvey of the Cornell of Laboratory of Ornithology used 18 years of Project FeederWatch data to quantify the changes in Evening Grosbeak abundance. Their analysis confirms our impressions: Evening Grosbeaks seem to be in a population decline. Over the past 18 years, the number of sites reporting Evening Grosbeaks fell by 50%. Flock sizes decreased by 27% at feeders where the grosbeaks still visited.

The authors do not know why the population is decreasing but argue that the reason for these declines needs urgent investigation.

The Boreal Chickadee has a more northerly distribution than the Black-capped Chickadee. Boreal Chickadees also prefer coniferous forest. In Maine, these chickadees occur in the mountains, in the spruce-fir forest of northern Maine and in the spruce-fir coastal forests from Mount Desert Island eastward.

Adam Hadley and Andre Desrochers of Universite Laval recently described the effects of logging practices on Boreal Chickadee habitat use in Quebec. They clearly showed that Boreal Chickadees prefer the taller (greater than 7 meters in height), commercially valuable stands of conifers (mostly balsam fir in their study area) during the winter. The birds typically move in stable flocks of four birds. The average flock territory is around 50 acres. Boreal Chickadees occurred less often in regenerating forest where the trees were between four and seven meters tall. The chickadees avoided clear-cut areas and younger stands with trees less than 4 m in height.

The authors expect that forestry practices in Quebec will result in substantial loss of prime Boreal Chickadee winter habitat over the next 20-30 years. Boreal Chickadees will likely show apparent habitat declines although the population may remain stable. The reason is that the winter flocks will need to expand their territory size in less preferred areas and therefore will be harder to detect.

On the positive side, Wild Turkey populations have risen rapidly over the past 20 years. In the early 1990’s, the sighting of a Wild Turkey was an unusual event in Maine. Seeing flocks of Wild Turkeys now is commonplace and many of us have them digging through our flower beds and vegetable gardens.

During the breeding season, male turkeys display and gobble to attract female mates. The toms have no parental role and therefore a tom seeks to have as many female partners as he can attract. We think that female turkeys may have multiple male partners as well so eggs from a single clutch may be fathered by multiple males.

Alan Krakauer of the University of California has made a fine contribution to our understanding of turkey mating systems in an article published in the Condor. His work was done in central California; one expects that similar results would be seen in eastern turkeys.

Krakauer used DNA fingerprinting techniques to examine the paternity and maternity of nestling turkeys. The DNA results do not lie. Krakauer took DNA samples from all the eggs of 32 nests. He showed that Wild Turkeys at his study site did not have as many partners as one might expect. Nestlings in 15 of the nests had the same mother and father. The broods from 14 nests were often half-brothers; they had the same mother but a different father. In seven nests, the embryo DNA showed that the eggs were produced by more than one female. Clearly, a sneaky female dumped one or more of her eggs into the nest of an unsuspecting female.

In songbirds, the female usually incubates the eggs. She develops a brood patch, an unfeathered area with an extensive blood supply to allow the female to transfer heat to her eggs. Margaret Voss and colleagues from Penn State described male incubation in Barn Swallows. Unlike female Barn Swallows, the males do not develop a brood patch. As a result, they are much less efficient in keeping the eggs warm than the female. Nevertheless, male incubation is better than having no incubation at all so male incubation gives the females the chance to feed for a longer period of time when she takes a break from her incubating duties.

[Originally published on October 31, 2008]

2008-11-23T17:34:00.001-05:00

For the Birds: Review of Roger Tory Peterson Biography

All students of nature are familiar with the name Roger Tory Peterson. Peterson is given much credit for the rise of field birding in this country and abroad. In 1934, he published his Field Guide to Eastern Birds. This book was a vast improvement over earlier identification guides to birds that were too bulky for field use, sparsely illustrated or incomplete in their coverage. Peterson’s guide was meant to be taken in the field. In later years, Peterson was always delighted to be asked to sign battered, well-used copies of his guide because that meant the field guide was used as he intended.

Peterson was innovative in painting birds from the same perspective, usually a lateral view looking to the right. The male was typically shown in front with the female partially overlapping behind the male. Perhaps his most useful innovation was the use of arrows to point to characteristics that are most useful in identifying species. His text descriptions were to the point and easy to understand. For instance, to identify the Snowy Egret he told the birder to look for the golden slippers.

Over the years, Peterson revised his eastern bird guide three times and a fifth edition was completed posthumously by colleagues. He also produced bird guides for western North America, Mexico, Europe as well as a wildflower guide. He painted the illustrations for all of these guides. For this 1980 revision of his eastern bird guide, he painted very bird anew. His publisher, Houghton-Mifflin, used these books a starting point for the Peterson Field Guide series. Specialists in other groups of organisms prepared field guides using the Peterson arrow system. I am sure you have seen these guides on such diverse groups as ferns, trees, reptiles and amphibians, butterflies, and mammals.

Peterson’s contributions to birds went far beyond the field guides. In his nearly 88 years of life, Peterson was an educator, photographer and conservationists as well as a popularizer of birds. His accomplishments can be appreciated by reading the newly published first biography of Peterson written by Elizabeth Rosenthal. The book is titled “Birdwatcher: The Life of Roger Tory Peterson” and it is a gem.

Rosenthal dug deeply in her exploration of this rather complicated man. She interviewed well over 100 people including this two sons from his second marriage, borrowed letters from a number of Peterson’s correspondents, scoured the archives of the Roger Tory Peterson Institute in Peterson’s hometown of Jamestown, New York and mined the literature for information on Peterson.

Rosenthal chronicles formative events in Peterson’s childhood and early adulthood, including his joining the Bronx Bird Club, a loosely organized group of boys and young men with keen interests in birds. Peterson had moved to New York City to take some design courses to hone his artistic skills and discovered this club. Several of the club members went on to distinguished careers in ornithology and wildlife biology.

Through a series of events, Peterson taught at the Chewonki School in Wiscasset, Maine where he began the strong interest in nature study there at persists to this day. Peterson also regularly participated as a leader at the fledgling National Audubon Society camp on Hog Island in Maine during summers in the mid 1930’s.

Rather than providing a strictly chronological account of Peterson’s life, Rosenthal covers his adult with a number of thematic chapters. Chapters overlap broadly. I think of each chapter as a layer of Peterson’s life. By the end of the book, the reader has a good understanding of the man’s accomplishments, ambitions and personality.

I knew about Peterson’s cross-country trip with the British ornithologist, James Fisher in 1953, chronicled in the book “Wild America”. I did not know that a tour guide, Gus Yaki, recreated the trip 30 years later and that Peterson joined portions of that tour. That is the mark of an influential person.

We learn that Peterson was not a confrontational man but held strong views about the importance of bird conservation. We learn of his efforts to protect the million flamingos that use Lake Nakuru in Kenya, the diverse Coto Donana region in Spain and early efforts to sound the alarm about the negative impacts of DDT on birds and other animals. He played a major role in the development of the World Wildlife Fund.

We discover that Peterson had his share of human foibles. He was a poor driver and a forgetful person. His concentration on his painting and his travels once he became a celebrity came at the cost of his family life.

By the end of his life, Peterson had been awarded 21 honorary doctorates and the Presidential Medal of Freedom. By reading Rosenthal’s biography, you will understand why.

[Originally published on October 18, 2008]

2008-11-23T17:31:00.002-05:00

For the Birds: Fox Sparrow; Citizen Ornithology Science Opportunities

In the grand spectacle of the fall bird migration, the arrival of October signals the end of the migration of most warblers and other insect-eating birds. For songbirds, I think of October as the month of the sparrows. Relying on the seeds of grasses and other plants, sparrows can find sufficient food through the fall. There are slim pickings of caterpillars for warblers and other insect-eating birds now.

I keep a sharp eye on the ground these days, particularly below our bird feeders. I’m looking for a noticeably larger sparrow than the Song Sparrows that are so common now. The sparrow I am seeking is the Fox Sparrow, one of the largest sparrows in North America.

Our Fox Sparrows share with the Song Sparrow a strongly streaked breast. As befits their name, Fox Sparrows in the east have a strong reddish cast to their upperparts and head. These are handsome birds.

Although Fox Sparrows nest sparsely in the northwestern part of our state, most of the Fox Sparrows we see are passage migrants. That is to say, the birds nest to the north of us and winter to the south. We see them coming and going during their spring and fall migrations.

Fox Sparrows nest in a large swath across the northern portion of North America from Labrador in the east, across the Canadian provinces into most of Alaska. Breeeding populations are also found at altitude in the Rocky Mountains into Colorado and in the Sierra Nevada down to central California. The wintering ground is essentially the southeastern quadrant of North America with some wintering in the lowlands of California.

Audubon saw Fox Sparrows in Labrador in 1834. The Fox Sparrows in Labrador have the rufous feathering of the birds that pass through Maine. Audubon had no idea how variable Fox Sparrows are across their breeding range.

This striking geographical variation has resulted in the description of 18 distinct subspecies grouped into three or four larger groups. An ornithologist at the University of Minnesota, Robert Zink, has analyzed the DNA of Fox Sparrows from many of these groups. His results suggest that there may be as many as four species all currently called Fox Sparrows. Common names have been given to these distinctive forms: the Reddish Fox Sparrow of eastern North America, the Sooty Fox Sparrow that nests from the Aleutian Islands of Alaska south to Washington state, the Slate-colored Fox Sparrow that nest in the Rockies and the Thick-billed Fox Sparrow nesting from Oregon south to southern California.

I find Zink’s recommendation that Fox Sparrows be split into several species compelling. However, the American Ornithologists Union Check-list Committee, the body that approves all taxonomic changes of Western Hemisphere birds, is not fully convinced and so far Fox Sparrow is considered to be a single, highly variable species. Stay tuned; I expect Fox Sparrow will be split into several species in the not too distant future.

The different types of Fox Sparrows show markedly different migratory strategies. The Reddish Fox Sparrows have a long migration from northern Canada breeding grounds to wintering grounds as far south as the panhandle of Florida. Californian Thick-billed Fox Sparrows migrate only short distances, sometimes just descending the mountain that they nest on to spend the winter.

Despite the broad geographic reach of these sparrows, significant gaps in our knowledge of their nesting biology exist. On the breeding grounds, Fox Sparrows are somewhat shy. Furthermore, they tend to nest in short, dense shrubs making nest-finding and observations of parents at the nest extraordinarily difficult. Add to these factors the fact that Fox Sparrows tend to nest where human density is low.

Winter Bird Counts

It’s not too early to think about the joys of winter birding. Any Maine birder has two opportunities to participate in an organized winter bird count. The first is the National Audubon Society Christmas Bird Count, which will occur from December 14 until January 4. A list of the dates for many Maine counts can be found at: http://www.mainebirding.net/events/cbc

Birders of all skill levels are welcome. Find a count on the list above close to you and give the compiler a call or email to join up. We now have over 100 years of data on the abundance of birds in the early part of winter.

A second opportunity is The Great Backyard Bird Count, organized by the Cornell Laboratory of Ornithology and the National Audubon Society. This count will be held in the deep of winter on February 13-16, 2008. Participants count the birds at their feeders and report their counts online. To sign up for this valuable citizen-science project, visit http://www.birdsource.org/gbbc/

[Originally published on October 4, 2008]

2008-11-23T17:29:00.001-05:00

For the Birds: Spencer Baird and the Army Surgeons

Careful study of shorebird flocks at this time of year can yield sightings of peeps that are a bit larger than the Least Sandpipers and Semipalmated Sandpipers that are so common this time of year. This larger sandpiper has wings that extend beyond the tail and tends to feed in the upper portion of the intertidal zone or lake edge. This species is the Baird’s Sandpiper. This species has been seen this fall in Fryeburg, Appledore Island, Cape Elizabeth, Scarborough, Reid State Park, Machias and Lubec.

Today’s column is not about this sandpiper but rather it’s namesake. Spencer Fullerton Baird was one of the great scientists of the 19th century. He made great contributions to ornithology and ichthyology. A prolific author, he also wrote papers on geology, botany, anthropology and general zoology.

Baird’s accomplishments are commemorated not only in the name of Baird’s Sandpiper but Baird’s Sparrow of the western U.S., Baird’s Trogon from Costa Rica and Panama, Baird’s Beaked Whale, a number of fish species and even a species of crab.

Baird was born in 1823 in Reading, Pennsylvania and graduated from Dickinson College in Carlisle, Pennsylvania in 1840. Baird became interested in birds in his mid-teens and began to assemble his own bird collection. He visited the Philadelphia Academy of Natural Sciences in 1839 to read the works of John James Audubon. Baird gathered the courage to write to Audubon in 1840 about a flycatcher that Baird thought might be a new species. Audubon responded in short order and the two became friends.

After graduating from Dickinson College, Baird began medical studies in New York City. Medical studies failed to captivate him and he discontinued his medical education after three months. Baird returned to Dickinson College where he accepted a position as professor of natural history. Baird was an extremely popular professor, leading students on long field trips and maintaining the natural history museum.

In 1847, Baird learned that the Smithsonian Institution was opening. He wrote to Joseph Henry, the first secretary of the Smithsonian, asking for a position as a curator. Baird heard nothing for a while but Henry eventually decided the Smithsonian should have a museum. He offered Baird the job of organizing the museum. Baird eagerly accepted in 1850. He shipped his collection to the Smithsonian, a collection that filled two railroad boxcars! This collection included over 500 species of birds. This generous donation became the core of what is now the United States National Museum of Natural History.

Baird served as the assistant-secretary of the Smithsonian from 1850 until 1878. He became secretary in 1878 when Joseph Henry died.

At the Smithsonian, Baird developed a large network of collectors and natural historians in this country and abroad. Their numbers were in the hundreds. He prepared detailed instructions for the collection and preparation of various kinds of organisms. These instructions were distributed to his network of collectors. He offered encouragement, advice, supplies and money in exchange for the steady stream of specimens arriving regularly in the museum. Baird described many of the new species the collectors found in honor of the collector.

During Baird’s tenure at the Smithsonian, westward exploration was capturing the imagination of many Americans. From 1850 to 1880, the U. S. government initiated a number of expeditions to map the regions and find suitable areas for roads and railroads. Many of these expeditions were conducted by the U. S. Army.

Baird realized a good opportunity when he saw it and recruited physicians with interests in natural history, especially ornithology and mammalogy, to accompany these army expeditions. These physicians collected specimens in their free time, often with the assistance of enlisted soldiers and even sometimes their commanding officers.

These physician/naturalists will be familiar because their names are memorialized in the names of western birds. Elliot Coues was probably the most influential of all of these surgeon/naturalists. The Greater Pewee was formerly called Coues’ Flycatcher. Born in New Hampshire, Coues published his first ornithological paper before his 20th birthday. He spent time in New Mexico and Arizona. Grace’s Warbler in Arizona was first collected by Coues in Arizona. The species was formally described by Baird and named in honor of Coues’s sister, Grace. Baird also named Virginia’s Warbler after the wife of another physician/naturalist, William Anderson.

Other surgeon/naturalists in Baird’s network were John Xantus (Xanthus’s Murrelet), Charles Bendire (Bendire’s Thrasher), William Hammond (Hammond’s Flycatcher) and Adolphus Heermann (Heermann’s Gull).

Baird retired from the Smithsonian to Woods Hole, Massachusetts. He played a major role in the creation of the Marine Biological Lab there, one of the most respected marine laboratories in the world.

[Originally published on September 20, 2008]

2008-11-23T17:22:00.002-05:00

For the Birds: Arctic Tern Migration; The Life of the Skies Review

The fall bird migration is picking up momentum. Swallows began massing in large flocks and heading southward by the middle of August. Shorebirds that nest on the arctic tundra are building in numbers along Maine mudflats, the first having arrived on their southward passage in July. Black Scoters, Surf Scoters, and Red-necked Grebes have already appeared along coastal waters. Much of the warbler migration will occur in September and sparrow migration in October.

The fall migration is a gloriously protracted spectacle. Without the need to claim a breeding territory or find a mate like spring migrants, fall migrants show less urgency.

The number of birds that participate in the fall migration in North America is staggering. I have seen one estimate of five billion birds moving southward on our continent.

Some migrations are relatively modest undertakings. For instance, the Common Loons that nest on our lakes need only migrate eastward to the ocean to spend the winter. Ruby-crowned Kinglets may only migrate as far south as Pennsylvania or eastern New York for the winter.

With the Olympics still fresh in our minds, considering the most impressive bird migrants seems appropriate. In the past few years, I have written about two of the most amazing species of migrating birds. Both Semipalmated Sandpipers and Blackpoll Warblers fatten along coastal portions of northeastern North America and then embark on a non-stop flight over the ocean of some 2000 miles to get to their South American wintering grounds.

Once these birds get south of the 30th parallel, the northeast trade winds help to propel them to the northeastern shores of South America but their migration is still stunning. These birds cannot stop to rest on the water and cannot feed along the way. They have to pack all the fat they will need to fuel their flight before they depart. These migrations require three to four days of non-stop flight.

But, the North American species that covers the most distance in migration is the Arctic Tern. Members of this species breed in the Western Hemisphere from Greenland at a latitude of 84 degrees south to Cape Cod. Their fall migration takes them to the edge of the pack ice in Antarctica. That requires a flight each fall of 12,000 miles!

Unlike the Semipalmated Sandpipers and Blackpoll Warblers, Arctic Terns can feed along their way since they dive for fish from the air. They can also rest on the surface of the ocean. However, 12,000 miles is an awfully long distance to cover in just a couple of months. The advantages are significant; Arctic Terns experience longer periods of daylight than any other species of bird in the Western Hemisphere.

When the Antarctic summer starts to wane in March, the Arctic Terns retrace their migration back to their northern breeding grounds. The record life span for an Arctic Tern is 34 years. The wings of this bird propelled the bird over 800 million miles in its lifetime. That feat is worthy of a gold medal.

The Life of the Skies

I’ve just finished reading The Life of the Skies: Birding at the End of Nature by Jonathan Rosen and enthusiastically recommend the book.

Describing the book is not easy; perhaps, the best way to describe the book is a meditation on birding at the beginning of the 21st century.

Rosen is a novelist and editor of Nextbooks who took up birding as an adult. Central Park, near his New York City apartment, is one of his favorite haunts although he has traveled broadly to pursue his birding passion.

Rosen interweaves several birding narratives in his book including ones on his efforts to see an Ivory-billed Woodpecker, visiting threatened birding hotspots in Israel along with historical accounts of John James Audubon, Henry David Thoreau and Alfred Russel Wallace, a contemporary of Charles Darwin who independently arrived at the concept of natural selection.

References to poetry appear often throughout the various chapters including poems by Robert Frost, Walt Whitman, Emily Dickinson and Wallace Stevens. He also frequently quotes the writing of Edward O. Wilson, the Harvard professor who is one of the most articulate defenders of the need to conserve the diversity of life on earth.

I found Rosen’s analysis of Robert Frost’s poem, The Ovenbird, to be particularly moving. Written around 1910, this poem is a lament for nature that is lost but still expressing a thread of hope for conservation.

The Life of the Skies explores the relationship between wild birds and humans and the scientific, spiritual and emotional ways that birding is important for humans. I thoroughly enjoyed this provocative book.

[Originally published on September 6, 2008]

2008-11-23T17:12:00.002-05:00

For the Birds: Bird Phylogeny Revised

The Swedish naturalist, Carl Linnaeus (1707-1778), developed the system of classification that biologists use today to order the rich diversity of life on earth. Linnaeus gave every species a two-part name, denoting the genus and the species of that organism. A genus contains a number of similar but distinct species. Genera (the plural of genus) are combined into families, families into orders, orders into classes and classes into divisions or phyla.

Linnaeus classified organisms based on their morphological similarity. Species belonging to the same genus are generally more similar to each other than they are to members of their own family that are in different genera.

A classification based on similarity of structure runs into two problems. First, two closely related species may diverge from each other over time and appear to be quite different. Second, distantly related species may converge on similar morphologies over time and thus be mistakenly placed in the same genus or family. As one example, Linnaeus placed the barnacles and the mollusks (snails, clams and their relatives) in the same group because all have a hard shell made of calcium. By looking at the early development of these organisms, biologists came to realize that barnacles are crustaceans and therefore more closely related to shrimp, lobsters and crabs.

Charles Darwin held the view that our classification system of life on earth should be a huge family tree, reflecting the relatedness of organisms. Understanding the relationships of the higher groups (orders, classes and phyla) is difficult based solely on morphology. Spirited arguments among biologists in the scientific literature about the relationships of these higher groups are common.

The analysis of DNA gives us a new way to develop the tree of life in the way Darwin envisioned. DNA is the molecule that ultimately determines the way an organism looks and behaves. The idea behind DNA comparisons is straightforward. More closely related species should have very similar DNA while more distantly related species should have more differences in their DNA.

For birds, the Yale biologist Charles Sibley, working in the 1970’s and 1980’s with his colleague Jon Ahlquist, were the first to use DNA comparisons to examine how the higher groups of birds were related. Their results were groundbreaking.

Sibley and Ahlquist used a technique called DNA hybridization. DNA is a double-stranded molecule with one strand being the mirror image of the other. By heating DNA, the double strands separate. Sibley and Ahlquist recombined single strands of DNA from two species to make hybrid DNA and determined how closely the two strands fit together. Species that made tight DNA hybrids were considered to be closely related.

Their many experiments produced a number of surprising results that are reflected in the current classification scheme used by the American Ornithologists Union and in the organization of field guides. For instance, Sibley and Ahlquist showed that the New World vultures are properly classified with the herons, not with the hawks and falcons. Vireos are not closely related to warblers as formerly thought but rather closer to the crows and ravens.

It is now possible to analyze DNA in much greater detail than Sibley and Ahlquist could do with their hybridization studies. Biologists can determine the sequence of the four molecules (called nucleotides) in DNA. Human DNA has three billion nucleotides; that’s a lot of information to compare!

As an example of the power of this approach, humans and chimpanzees have DNA that differs by less than 1%. Our DNA is slightly less similar to that of gorillas and even less similar to orangutans. So using DNA comparisons, we know that chimpanzees are the closest living relatives of humans and gorillas are the next closest of the great apes to us.

A recently published paper by Shannon Hackett and colleagues in the journal Science presents the results of DNA sequence comparisons for 169 species of birds, representing all of the major groups of birds. Like the work of Sibley and Ahlquist, many surprising relationships were found. We can expect the order of birds in our field guides and checklists to change to reflect his new work.

Here are some of their major findings. The perching birds (the passerines) are most closely related to the parrots! Falcons are closely related to these two groups of birds but not to the hawks and eagles. Thus, the falcon family and the hawk family have converged. The closest relatives of the penguins are the albatrosses. Unlike Sibley and Ahlquist, the new papers shows New World vultures are closest to the hawks and eagles. You can see further results of this important paper at: http://whozoo.org/birds/birdphylogeny.html

[Originally published on August 30, 2008]

2008-11-23T17:10:00.002-05:00

For the Birds: Plover and Sandpiper Feeding

Shorebird migration is underway. In the past week, Maine birders have found Greater Yellowlegs, Lesser Yellowlegs, Short-billed Dowitchers, Semipalmated Sandpipers and White-rumped Sandpipers. Most of these species nest in the Arctic. The window of opportunity for nesting in the Arctic is short so it is not surprising that these birds have departed the high latitudes already.

For many Arctic-nesting shorebirds like the Semipalmated Sandpiper, two pulses of migration are seen. The first pulse, the one we are beginning to see now, is almost entirely adult birds. These birds have left their young on the breeding grounds, in many cases before the young have even learned to fly.

Shorebirds do have precocial development; they hatch with feathers and can forage for food shortly after hatching. So, adults departing early is really not a form of child neglect. The young will eventually learn to fly and then depart on their migration. These juvenile birds, arriving in Maine mostly in September, constitute the second pulse of the migration.

Most migratory birds have their migration route hard-wired rather than having to learn a migration route. That becomes obvious with birds like Semipalmated Sandpipers who do not have mom or dad to show them the way. Mistakes do occur, however. The chance of a first-year sandpiper showing up at some unexpected location is greater than the chance of an adult appearing at the same place.

To fuel their migration, shorebirds have to feed gluttonously along the way. I think it is fascinating to watch how different species of shorebirds feed.

Let’s start with the plovers. A careful look at a plover will indicate that its eyes are quite large relative to its head size compared to most sandpipers. These large eyes suggest that vision is of primary importance in finding food. That is indeed true.

The foraging behavior of plovers can be called run-and-peck. A plover on an intertidal flat will look for movements at the sediment surface indicating the presence of a crustacean or polychaete worm. It will then run to the location and attempt to grab the prey item.

Keep an eye out for a behavior of Black-bellied Plovers called foot trembling. A plover will stand on one leg and vibrate the other food right at the sediment surface. This trembling appears to set up vibrations that a bloodworm or other invertebrate predator interprets as a possible prey item. The bloodworm comes to surface looking for dinner and finds that it is on the menu of the plover!

Sandpipers, the other major group of the shorebirds, rely on touch to find their food. The bill of a sandpiper is richly endowed with touch receptors, particularly at the tip. A sandpiper probes the sediment until the touch receptors detect the movement of a small invertebrate and the bill clamps down on the prey item.

Particularly for long-billed sandpipers like dowitchers, a significant amount of energy would be required to open the long bill while it was stuck in several inches of mud. To make opening the bill easier, sandpiper bills are rhynchokinetic. That is, the can open the tip of the bill without having to open the portions of the bill closer to the skull. You can see a nice picture of this behavior at: http://birdblog.merseyblogs.co.uk/archives/2006/07/its_called_rhyn.html

Sandpipers on an intertidal flat occur in characteristic spots. Dowitchers and Stilt Sandpipers with their long bills wade in up to their bill and probe rapidly into the sediment. Their probing is often quite rapid and is referred to as stitching (like a sewing machine). Dunlins with somewhat shorter bills tend to forage right at the water’s edge. Short-billed sandpipers like the various peeps feed above the tidemark.

One advantage sandpipers have of using touch rather than sight to find food is that sandpipers can feed at night. Nocturnal feeding is particularly valuable during migration when sandpipers are trying to pack on fat as quickly as possible.

Some years ago, I determined the predation rate of Semipalmated Sandpipers in the Bay of Fundy on their favored prey, the small crustacean Corophium volutator by videotaping foraging birds. Corophium is about 3/8 inch long. I found that each sandpiper was taking about 17,000 Corophium each day. That goes a long weight toward explaining how these sandpipers double their weight in only two weeks.

Recent research has shown that Western Sandpipers acquire a majority of their energy by consuming biofilms. A biofilm is a thin layer of bacteria, detritus and sediment held together by a glue-like material secreted by microalgae and bacteria. Biofilms may be important in the diets of other shorebirds too.

[Originally published on August 23, 2008]

2008-11-23T17:06:00.001-05:00

For the Birds: Ontario Conservation Easement

Birds often find humans to be rather undesirable neighbors. In the last three columns, I wrote about the decline of some grassland birds and some efforts to stop the decline. One of the most effective conservation tools that environmental managers have at their disposal is habitat protection. In Maine, remaining grasslands like the Kennebunk Plains and the Wells Barren are now protected, thanks to the work of The Nature Conservancy and other organizations.

But grasslands are not the only habitats we should be worried about. The notion that we have enough forest in Maine and elsewhere at northern latitudes is shortsighted. We know that highly fragmented forests may not be acceptable habitat for a number of breeding birds. Species like Barred Owl, Ovenbird and Scarlet Tanager seek nesting territories within large tracts of unfragmented forest. Highly fragmented forests simply will not do.

The government of the province of Ontario recently announced some great news for conservation, including a great boon for birds that breed in the boreal forest. The Premier, Dalton McGuinty, proudly revealed that the Ontario Government will protect at least half of Ontario’s boreal forest. The protected area will include 86,900 square miles of boreal forest. That area is nearly three times the size of Maine! Corridors between large areas of forest help to minimize the effects of forest fragmentation as unprotected areas are developed and altered.

The decision was primarily impelled by a letter sent to the Canadian government on behalf of over 1500 scientists worldwide, who strongly recommended that 50% of Canada’s boreal forest be protected. These scientists identified the 1.4 billion acre Canadian boreal forest as one of the largest intact forest and wetland ecosystems remaining on earth.

The boreal region is one of the last truly wild spaces on earth. It is home to over 200 sensitive species of animals, such as polar bears, wolverines and caribou. Many of these species are threatened or endangered. The protection of this area will be a huge step in preventing a decline in the biodiversity of the region.

Preserving large tracts of this boreal region is necessary because of increasing pressure from corporate logging and mining concerns. Oil and gas operations represent threats to the habitat as well.

Over 300 species of birds are found in the boreal forests of North America. This forest ecosystem provides breeding habitat for over 40% of the population of 21 warbler species. Nearly 100 species of birds have the majority of their population in the boreal forest during the summer. Ontario’s landmark decision is reason to cheer for all birders.

The protection of this large tract of forest will help combat global warming. The absorption of carbon dioxide by the boreal forest trees is a significant carbon sink.

Altruism

Altruism is the term that biologists use to describe selfless behavior. Although examples of altruism abound for humans, biologists are skeptical of claims of altruistic behavior in other species. After all, much of the behavior of an organism can be understood in trying to reproduce and hence perpetuate one’s genes. Helping other organisms at one’s own expense is hardly the way to get your genes into the next generation.

Some animal behaviorists think that selfless behavior can be worthwhile as long as it is reciprocal. Two organisms might strike a bargain where each agrees to share food if the other is unable to find food. This reciprocal altruism seems like a win-win situation, right? The problem is that cheaters win. I might be more than happy to eat some of your food when I have none but I may selfishly choose not to share when I have food and you do not.

Some recent work on Pied Flycatchers, a species found in Eurasia, has shed some light on how cheaters in system of reciprocal altruism might be punished. Pied Flycatchers will mob a predator, jointly assaulting the predator to drive it away. When a predator is seen, a Pied Flycatcher will give an alarm call to attract other Pied Flycatchers to join the mob. Cooperation usually results in the predator being chased away.

However, some Pied Flycatchers are cheaters. They may not respond to an alarm call and help mob the predator. Experiments done in the field showed that when a Pied Flycatcher that did not help mob a predator sees another predator and gives the alarm call, the birds that mobbed the first predator refuse to help the cheater. It’s a case of “You didn’t help us mob earlier so we are not going to help you now – good luck chasing away that hawk on your own”. So, this study has identified a case of reciprocal altruism where cheaters do not prosper.

[Originally published on August 9, 2008]

2008-07-30T10:18:00.004-04:00

For the Birds: Upland Sandpiper and Eastern Meadowlark

This column is the last of three on grassland birds in Maine. In today’s column, we will take a look at Upland Sandpipers and Eastern Meadowlarks, both of which require grasslands for nesting.

Like the American Woodcock, the Upland Sandpiper is a shorebird that has adopted a purely terrestrial lifestyle. Don’t look for Upland Sandpipers foraging on intertidal mudflats with Sanderlings, Semipalmated Sandpipers, Greater Yellowlegs and other members of the sandpiper family. Rather, Upland Sandpipers prefer rather dry habitats with a dearth of trees. Grasslands are their natural breeding areas although lowbush blueberry barrens can serve as nesting sites as well. Grassy areas at airports also provide nesting habitat.

An Upland Sandpiper is a large sandpiper with a long bill. Its neck is markedly thin and its head seems to be too small for its body. The plumage consists of black, brown and tan feathers that make the bird cryptic in the tall-grass habitats it prefers.

The call of the male is a sound that will stick with you. Many people will not recognize the eerie whistle of the male as coming from a bird. Efforts to represent the whistle in human syllables include “whooooleeeeee, wheeelooooo-ooooo”. To some, the call sounds like a “wolf whistle”.

The greatest abundance of nestling Upland Sandpipers is found in the Dakotas, Nebraska and Kansas. Populations can be found westward to the Rocky Mountains and eastward, occurring patchily in New England and some of the Mid-Atlantic States. These birds winter on the pampas and other grassland habitats in South America.

In most nesting areas, Upland Sandpipers have suffered at the hands of humans. First, early European settlers killed them for food as well as collected their eggs. Later, market hunters took even more. But, the most devastating effect caused by humans was the plowing of the tall-grass prairies to plant crops. Breeding Bird Survey data show that numbers of Upland Sandpipers continue to decline over most of its breeding range, North Dakota being the only state where Uppies are holding their own.

The last species we will consider is the Eastern Meadowlark, a species associated with farmlands. Before European settlement, Eastern Meadowlarks were dependent on native grasslands for habitat. Unlike the Upland Sandpiper, meadowlarks have proven to be adaptable, readily nesting in pastures.

Eastern Meadowlarks are found broadly throughout eastern North America. Their northern limit occurs from Minnesota eastward through Ontario and into the Maritime Provinces. Meadowlarks can be found throughout the states south of this line. They even extend discontinuously throughout Central America.

In most of their range, Eastern Meadowlarks are non-migratory. The meadowlarks in New England and other northern states withdraw in late fall to warmer portions of the species’ range. Meadowlarks usually return to Maine in late March to April.

Eastern Meadowlarks are distinctive birds. They have a bright yellow breast with a V-shaped black patch on the upper breast. The description of a yellow V-necked sweater is certainly apt. On the side of the face below the eye, a whitish stripe, the malar stripe, is distinctive. The Western Meadowlark, which overlaps with Eastern Meadowlark in some parts of their ranges, is almost a dead ringer for the Eastern. However, the malar stripe of the Western Meadowlark is mostly yellow.

The upper side of the Eastern Meadowlark is mottled gray, black and brown, allowing the bird to blend in well with its grassland habitat. The outer tail feathers are white, making these feathers a good field mark for a flying meadowlark.

Like other grassland birds, Eastern Meadowlarks will be detected first by their voice. The song of this species is a series of clear, slurred whistles. Some ornithologists have tried to capture the cadence of the song as “song of the earth”.

Despite their use of agricultural fields for nesting, Eastern Meadowlarks are showing alarming declines throughout much of their range. Part of this stems from a reversion of old farms back to forests. Human encroachment to breeding areas also plays a role in the decline of these birds.

As an overview, we have seen that grassland birds are declining through much of their range. While we should be concerned, there is some reason for hope. In recent years, the science of landscape ecology has matured. Landscape ecologists study how variation in habitat at large scales affects the distribution of organisms. Landscape ecologists understand the importance of interconnected reserves, of conserving habitat near already protected habitat and of evaluating the conservation potential of available tracts of land. Active management of grasslands will need to be continued to prevent forests from taking over.

[Published on July 26, 2008]

2008-07-30T10:10:00.001-04:00

For the Birds: Grassland Sparrows

This column is the second of three on grassland birds in Maine. In today’s column, we will take a look at three sparrows (Savannah, Vesper and Grasshopper) that require grasslands for nesting. In the next column, I’ll discuss the Upland Sandpiper and Eastern Meadowlark and end with some of the conservation challenges of these habitats.

The three sparrows in today’s column are more often heard then seen so learning to recognize them by song is the best way to find these somewhat shy birds.

The Savannah Sparrow is the most common of the three. Its breeding range covers most of the northern two-thirds of North America, extending into the arctic tundra. It is a migratory breeder in most parts of its range. During the winter, Savannah Sparrows withdraw to the southern tier of the United States and into much of Central America.

The species was named the Savannah Sparrow by Alexander Wilson, a contemporary of Audubon. Wilson collected a specimen in Savannah, Georgia and honored this charming southern city by naming a sparrow after it.

The song of the Savannah Sparrow has a distinctive buzzy quality. The song typically begins with a few short notes, then a buzzy trill and a final note or two of lower pitch. The song carries well, particularly the trill and final notes. A singing male can usually be seen singing from a grass stem or short shrub.

Visual identification of this species is straightforward. A Savannah Sparrow has a streaked breast like a Song Sparrow. The Savannah Sparrow’s streaks are less bold than those of a Song Sparrow and typically do not coalesce into a dot as in most Song Sparrows. The best field mark is the yellow line above the eye that is especially conspicuous in front of the eye.

During the breeding season, Savannah Sparrows mostly feed on insects. Outside of the breeding season, they switch to a diet of seeds they are able to find on the ground.

Like the Bobolinks discussed in the last column, a male Savannah Sparrow may have more than one female partner. The insect abundance in a grassland or meadow is abundant enough to allow a male to help feed two clutches of nestlings.

Vesper Sparrows have a broad distribution in North America, not quite rivaling the broad range of the Savannah Sparrow. Vesper Sparrows nest across the middle third of our continent and winter in the southern tier of states south into Mexico.

The song of the Vesper Sparrow has a distinctive beginning of two to four long clear notes followed by a downslur and then a series of flute-like trills, first rising in pitch and then falling. Vesper Sparrows sing throughout the day but continue to sing in the evening after most birds have ceased to sing. Those evening songs are the reason the bird is called the Vesper Sparrow.

The dependence of Vesper Sparrows on grassland habitats is doubly reflected in its scientific name, Pooecetes gramineus. Pooecetes means “grass dweller” and gramineus means “fond of grass”. In Maine, grasslands and blueberry barrens are the best places to find this sparrow.

The Vesper Sparrow is a rather large sparrow. These sparrows have a streaked breast and distinctive white outer tail feathers. Some of the wing coverts are rufous in color, giving rise to the older common name of Bay-winged Bunting.

We believe that Vesper Sparrows were rare in the east before European settlement. The clearing of forest for pastures allowed Vesper Sparrows to increase in eastern North America. The species is declining in the east now because of the reversion of so many farms to forest.

Grasshopper Sparrows are the least common of the three grassland sparrows. They breed broadly throughout the eastern two-thirds of the United States but are usually found in low numbers. Their populations have declined in many portions of their range because of the destruction of grasslands and prairies these birds require for nesting.

The common name of this species stems from its insect-like songs. Male Grasshopper Sparrows are unusual among sparrows in that they sing two distinctly different songs. Their Primary Song consists of one to three high-pitched notes followed by an insect-like trill. It can be described as tsick, tsick, tsurrrrrrr. This song is used to repel other males from its territory. A second song, the Sustained Song, consists of a more musical series of short buzzy notes given either from a perch or in flight to attract a female.

The pronounced flattened head, the large bill and upper orange breast make the Grasshopper Sparrow easy to identify once sighted.

[First published on June 28, 2008]

2008-07-30T10:08:00.001-04:00

For the Birds: Bobolinks

A suite of birds collectively called the grassland birds nest in New England. This group of birds includes the Upland Sandpiper, Savannah Sparrow, Vesper Sparrow, Grasshopper Sparrow, Eastern Meadowlark and Bobolink. Wildlife biologists are concerned about this group of birds because their populations are declining in New England, including our Maine populations.

Grassland habitats are rather limited in New England and have invited development into farms or towns because tree cutting is not required adapt the line for human uses. Fortunately, grassland birds are adaptable and often nest in hayfields or blueberry barrens. However, many hayfields in Maine are no longer maintained and are reverting to forest. We have much more forested land now in Maine than we did in 1900. Thus, the decline of their required habitat helps explain the decline of these grassland birds.

Today’s column is the first of three on the grassland birds of Maine. We’ll start with one of the most beloved birds of Maine, the Bobolink.

With their beautiful plumage (mostly black with white on the back and wings, and a yellow patch on the back of the head and nape), male Bobolinks are strikingly handsome birds. Some waggish authors have described them as having tuxedos on backwards.

The female is nondescript, brown on the uppersides with streaking and yellowish underneath. This plumage makes them nearly impossible to see in a grassy field.

The male’s song is equally distinctive: a long, bubbly series of metallic notes. A student of mine, an obvious Star Wars fan, said the song sounds like the robot R2D2! The Bobolink song has inspired poetry. The American poet, William Cullen Bryant, based his poem “Robert of Lincoln” on the song of the Bobolink.

The breeding range of Bobolinks extends across the northern tier of the United States from Maine to Washington as well as the southern portion of the Canadian provinces.

Bobolinks winter south of the equator in South America, The wintering habitat is the grasslands known as the pampas in southwestern Brazil and Argentina. Each year, a Bobolink makes a round-trip of 12,000 miles. We know of one banded female that lived to be nine years old. Presuming she made the trip every year, she traveled the equivalent of circling the globe at the equator four times.

Orientation and navigation have been fairly well studied for Bobolinks. Researchers have found that the primary cue for navigation in Bobolinks is the earth’s magnetic field.

Bobolinks arrive in central Maine by the second week of May. Males are conspicuous as they stake out territories and await the arrival of the females. When a female passes overhead, a male will perform an aerial song display to attract the female’s attention. If the female lands, the male will go through a series of courtship behaviors to court the female. These behaviors include a low circle flight on stiffly held wings and an abrupt drop to a low perch or the ground. When the male drops, he holds his wings in a shallow V (like the gliding silhouette of a Turkey Vulture) and gives a few buzzy notes, dangling his legs on the descent. When he touches the ground, he may hold his wings in the shallow V for several seconds.

A female is slow to choose a mate. A male may have to perform this elaborate courtship sequence five times a minute for a half-hour or more. A pair bond is formed when the female leads the male on a long chase, flying for up to six minutes.

Bobolinks are examples of polygynous birds; a male may have more than one female on his territory. The frequency of polygyny seems to be related to habitat quality. In high quality habitats where food is easier to find, a male frequently has two or more mates. In lower quality habitats, single females are typically found with the males. In Wisconsin, over half a population of males had at least two mates and one male had four mates. On the other hand in New York, fewer than 15% of the males had more than one mate.

Nests are always made on the ground in dense vegetation. The nest is usually located at the base of herbaceous, non-grassy vegetation like goldenrods or clover. The female chooses the nest location and builds the nest in one or two days.

A female typically lays five eggs although as many as seven can be laid by some females. Both the female and the male feed the young. Even a male with multiple mates participates in feeding although most assistance may be given to his primary mate.

[First published on June 14, 2008]

2008-07-30T10:05:00.002-04:00

For the Birds: Red-eyed and Philadelphia Vireos

Red-eyed Vireos have returned from their South American wintering grounds. One of the most common songbirds in North America, the Red-eyed Vireo’s song is a distinctive but somewhat plain series of two- and three-note phrases. Some authors render the song in human terms as “here-I-am, where-are-you, over-here, in-the-tree” that will resonate with anyone who has heard a Red-eyed Vireo singing. Red-eyed Vireos are energetic songsters, singing throughout most of day with rates as high as 85 phrases/minute.

The Philadelphia Vireo occurs in northern New England and much of southern Canada. This vireo closely resembles the Red-eyed Vireo but has a less distinct line above the eye and has a yellow wash on the underparts. The Philadelphia Vireo is also smaller, averaging 12 grams in weight to the 17-gram weight of a typical Red-eyed Vireo. Both species can be found in the same deciduous woodlands.

Most nesting male songbirds defend their territories against other males of its species. If you play a recording of a Yellow Warbler in the territory of a Yellow Warbler, the male will quickly come toward the source of the sound and look to chase off the unwelcome intruder. However, playing a tape of the song of a Black-throated Blue Warbler or a Chestnut-sided Warbler will produce no reaction by the Yellow Warbler. In general, male songbirds defend their territories against members of their own species but not against members of other species.

The two vireo species above provide an exception to this rule. Red-eyed Vireos and Philadelphia Vireos defend their territories against their own species and against the other species. In other words, both vireos show interspecific (between-species) and intraspecific (within-species) territoriality.

The song of the Philadelphia Vireo is very similar to the singsong phrases of the Red-eyed Vireo song. Even highly experienced birders pass off singing Philadelphia Vireos as the more common Red-eyed Vireos. The reason for the similarity will soon be apparent.

In northern New England forests, insect prey may become quite hard to find during the breeding season. Because both vireos eat largely the same species of insects, there is an advantage for a territorial vireo to keep a member of its own species and members of the other vireo species away from its food sources.

In most cases, the vireos avoid direct confrontations over the boundaries of a territory. Instead, a territorial bird proclaims his ownership of a territory by singing from perches throughout his territory. Similarly adjacent territory owners sing throughout their territory. The neighboring birds recognize unseen but real boundaries, avoiding physical interactions.

In the case of actual fighting between the two vireo species, the smaller Philadelphia Vireo usually comes out on the short end. One observed fight involved three minutes of violent contact, wing beating and pecking, with the larger Red-eyed Vireo winning the battle.

The problem the Philadelphia Vireo has is how to maintain exclusive ownership of a territory, defending against a larger and stronger Red-eyed Vireos that may be trying to expand his territory to find scarce food. Philadelphia Vireos have solved the problem by becoming a social mimic. These birds mimic the song of the Red-eyed Vireo.

Play-back experiments have shown that Red-eyed Vireos cannot tell the difference between a Red-eyed Vireo song and a Philadelphia song. No wonder birders have trouble telling the two species apart by song! On the other hand, Philadelphia Vireos can distinguish between a Philadelphia Vireo song and a Red-eyed Vireo song.

Red-eyed Vireos assume that a neighboring Philadelphia Vireo is a Red-eyed Vireo and accept it grudgingly as a neighbor. If the Red-eyed Vireo only knew its neighbor was the meek Philadelphia Vireo, the latter could be evicted. Philadelphia Vireos mimic the song of the Red-eyed Vireo to level the playing field; it’s a case of brains over brawn.

Computer analysis of the songs of these two species reveals that Red-eyed Vireos never sing the same phrase twice in succession. Philadelphia Vireos, occurring in the absence of Red-eyed Vireos, may sing the same phrase twice before a new song is sung. However, in the presence of a Red-eyed Vireo, the Philadelphia Vireo never gives identical consecutive phrases, indicating that the species actively mimics the Red-eyed Vireos. Pretty clever birds!

[First published on May 31, 2008]

2008-06-04T11:47:00.002-04:00

For the Birds: Spring Migration; Hog Island Camps; Maine Butterfly Survey

Migration

The marvelous spectacle of spring migration is here. Soon, the Black-billed Cuckoos, Blackpoll Warblers and Yellow-bellied Flycatchers will arrive in good numbers. The appearance of these late-arriving species signals the end of the spring migration.

Today, I want to consider why birds migrate. Each spring, several billion birds stream into North America from Caribbean islands, Central America and South America where they have spent the winter. Why do so many birds undertake these arduous migrations? The benefits must exceed the costs. What are the benefits migrating breeders receive?

To answer these questions, we have to understand both why birds migrate north to breed and why they leave their northern breeding grounds to return to tropical or subtropical areas. The explanations stem from the fact that the earth is tilted on its axis.

Let’s start with equatorial regions. Despite the tilt of the earth, equatorial regions have twelve hours of daylight each day. As one proceeds north, the length of day and night becomes unequal. When the northern hemisphere is tilted toward the sun, we have summer and temperate regions have day lengths that increase as one moves toward the North Pole.

The long summer days mean that plants can photosynthesize for sixteen hours or more each day, longer than plants at the equator. So during the northern summer, plant production spikes, providing food for insects that in turn provide food for birds. During the northern summer, food availability in temperate regions may exceed that of tropical regions. Birds migrate to the north to take advantage of the summer flush of food. The further north one goes, the longer the day length and bigger the spike in plant growth.

All good things must come to an end and the movement of the earth around the sun ultimately leads us to autumn with ever-shortening day lengths. Plant production decreases as light becomes less available and temperatures fall. Insect abundance declines. Many migratory breeding birds depend on insects so must leave for southerly areas to avoid starvation.

The cost of migration is more than paid for by the abundance of food in the summer at higher northern latitudes. But not all tropical birds migrate. What are the costs and benefits of staying put? The benefit is the energy saved by not migrating. The cost is that competition for food is very high in the tropics and destruction of nests by predators is very high. Tropical birds typically have multiple nests each season with a modest number of eggs, most of which are doomed to failure.

Hog Island Audubon Center

A landmark of environmental education since 1936, Hog Island Audubon Center’s residential programs educate, adults, children and families about coastal wildlife in Maine. The sessions are based on a 330-acre island in midcoast Maine’s Muscongus Bay. The sessions are led by some of the world’s most respected naturalists and environmental educators. You can find more information about their offerings at: http://www.maineaudubon.org/explore/camp/hi_overview.shtml

I want to call your attention to a new session called Family Birding Adventures geared for families with kids between the ages of six and thirteen. One of the highlights of the week will be a trip to Eastern Egg Rock to see nesting Atlantic Puffins. The session will be led by Jason and Laura Guerard, naturalists from the Cape May Bird Observatory. Jason and Laura met on Hog Island and Jason later proposed to her there. For more information, visit the website above or call (888) 325-5261 ext. 215.

Maine Butterfly Survey

The Maine Butterfly Survey, a five-year project to map the distribution and abundance of the butterflies and skippers of Maine, has begun its second year. This project relies heavily on volunteers. The first year yielded over 1500 records (specimens or photographs). Volunteers established four new state records and a large number of county records in the first year of the project. Two volunteers photographed Pipevine Swallowtails in late September 2007. These two records represent the first records of the species since 1907. You can see all of the 2007 records at the MBS website: http://mbs.umf.maine.edu/

As the Volunteer Coordinator for the project, I would like to encourage you to participate in the project. All participants are asked to attend a training workshop. Each workshop participant will be given equipment, a handbook and voucher forms. The last 2008 workshop will be held on Saturday, June 21 at Colby College in Waterville. The workshop will begin at 9:30 and conclude around 2:30. Lunch will be provided. If you are interesting in attending the workshop, please email me to reserve a spot. Enrollment is limited.

[originally published on May 17, 2008]

2008-06-04T11:44:00.002-04:00

For the Birds: New Bird Books for Beginning Birders

The spring migration is perhaps the most exciting time of year for North American birders. After a long Maine winter, the sounds of the first Eastern Phoebes and Red-winged Blackbirds and the sights of colorful warblers hold the promise of a glorious Maine summer. There is nothing like a spring birding excursion to hook a novice on birding.

Two books geared for beginner birders have recently appeared. One is meant for adults and one for kids. I’ll review the two books in today’s column. Perhaps, you have a friend or family member who might appreciate a copy of one of these books.

Finding Your Wings, written by Burton Guttman, is a different kind of book in the Peterson Field Guide series. This book is really a workbook designed to help a person new to birding to learn how to really look at birds how to identify them. Along the way, a diligent user of Finding Your Wings will learn much about bird behavior, classification and the etiquette of birding.

This workbook is designed to be used in conjunction with a field guide of North American birds. The workbook is specifically written to accompany either Roger Tory Peterson’s A Field Guide to Birds of Eastern and Central North America or A Field Guide to Western Birds. However, any North America field guide can be used in conjunction with Finding Your Wings.

The workbook begins with basic principles and skills of birding, continuing with an overview of the major bird orders and then more detailed descriptions of the topography of birds. Other chapters deal with molting, identifying birds in flight and learning to identify birds by their songs or calls. The book concludes with six chapters on groups of birds that pose particularly challenging identification problems. Bird groups covered include hawks, shorebirds, gulls and sparrows.

The content of the book sounds like standard fare for a birding book. The unusual, and I think innovative, aspect of Finding Your Wings is the activities and quizzes that fill the book. Doing the activities and taking the quizzes is key to getting the most out of the workbook.

Four kinds of activities are used in the workbook. Indoor Exercises require the reader to refer to a picture provided or pictures in a field guide to answer questions. A reader might be asked to look at the account for a Clay-colored Sparrow and then write down a description of the head of the bird. In so doing, the reader would learn the names of distinctive markings like the supercilium, auricular stripe and malar stripe. Answers are provided at the end of the book.

Field Exercises require the beginning birder to make observations in the field, such as determining the wing beat rate of different birds. Quizzes allow readers to test their knowledge gained from the Indoor and Field Exercises. Finally, several Games are described that are great for social learning.

The second book, also in the Peterson Field Guide series, is called The Young Birder’s Guide to Birds of Eastern North America by Bill Thompson III. This field guide was developed with the advice of Thompson’s 11-year old daughter and other members of her fifth-grade class. The field guide is designed to be used by kids on their own.

The field guide begins with the usual generic information on birding: binoculars, bird morphology, field guides, birding clothing. One section seeks to convince youngsters that birding is cool and that they should not be self-conscious about going birding.

The bulk of the book is the description of 200 species of common birds found in eastern North America. A page is devoted to each species. Of course, the amount of text one expects in a typical field guide is reduced in this “for kids” guide. Each page has one or two color photographs and a range map, covering all of North America. A line drawing is provided for each species, showing some interesting behavior. For instance, the drawing of the Hermit Thrush shows the distinctive behavior of these birds in raising the tail rapidly and then slowly letting it fall to a normal position. Each species account has five text sections. Look For provides brief information on the characteristics used to identify the species and Listen For gives a description of the vocalizations. The Remember section is used to emphasize distinctive identification features or behaviors. Find It describes the habitat of each species. Finally, a WOW! section describes a neat feature of a species such as the courtship flight of the Scissor-tailed Flycatcher or 1800-mile non-stop migratory flight of Brant.

[Originally published on May 3, 2008]

2008-06-04T11:41:00.002-04:00

For the Birds: Human-caused Bird Extinctions

Tuesday is Earth Day. I hope you will take the time to think about how you can make a difference in the protection and conservation of our planet’s organisms and resources. Go to http://ww2.earthday.net/ to find out about Earth Day activities in your local area.

In the last column, I wrote about sources of bird mortality. Many birds die because of direct human activities (for example, overhunting) or indirect effects of our use of the earth (for example, habitat destruction and pollution). Today, we will consider birds that have been pushed over the brink to extinction because of human activities. This sobering topic should make us all take Earth Day even more seriously. Extinction is forever.

Over the past 500 years, over 140 species of birds become extinct. With the exception of only about a dozen species, these birds were driven to extinction by human activities. Of the roughly 11,000 existing birds species, 1200 are currently in danger of extinction.

The majority of these extinctions occurred on oceanic islands. Many of these islands are small so population sizes are never very high. Many birds on oceanic islands become flightless over time and are therefore not able to escape from human hunters. Finally, birds on oceanic islands with few predators are often fearless in the presence of humans or introduced predators.

The Dodo provides an instructive case study for the extinction of island bird species. This species belongs to the order of birds that includes the pigeons and doves. The Dodo was flightless and most individuals were about three feet tall, weighing more than 40 pounds. They were found only on the island of Mauritius, an island off the coast of Madagascar. Dodos were fruit eaters in the Mauritian forests.

Dodos were certainly extinct by 1681, only 174 years after Europeans first became aware of them. Their demise began with the colonization of Mauritius by Dutch settlers around 1600. Although Dodos would have been easy for humans to kill, journals of Mauritian visitors indicate that the meat of Dodos had an unpleasant flavor and was quite tough. Humans hunted other birds, like the Red Rail, for food. The dramatic decline of the Dodos was rather caused by the cats, pigs and monkeys (Crab-eating Macaques) that the Dutch settlers brought with them. These introduced animals took the eggs or nestlings from the Dodo nests on the ground. By cutting forests and hence reducing Dodo habitat, humans accelerated the extinction of the Dodo.

Mauritius and nearby islands were home for 27 species of birds found uniquely on those islands. Today, 24 of those species are extinct. Such is the footprint of human settlement.

Hawaii is notable for a remarkable suite of birds called Hawaiian honeycreepers, found only in Hawaii. Related to our finches, the honeycreepers have not fared well with human development of the Hawaiian Islands. In the past 200 years, ten of the 31 species have been driven to extinction and several others are endangered.

Understanding the causes of extinctions is sometimes difficult. In New Zealand, 25 species of flightless birds called moas existed until about 300 years ago. We know that Maoris colonized New Zealand about 650 years ago and certainly ate moas and their eggs. However, the New Zealand climate has been changing over the past thousand years, reducing the grasslands the moas favored at the expense of expanding forests. How much of the blame for the extinction of the moas should be pinned on humans? We don’t know for sure.

But bird extinctions don’t happen only on islands. We have lost at least three species of North American birds in the past 200 years. We can clearly point an accusing finger at ourselves for two of these extinctions.

The Passenger Pigeon was once the most abundant bird in North America, migrating in astoundingly large flocks. They were colonial breeders, nesting sometimes in groups of 100,000 birds or more. The pigeons were hunted commercially as a cheap food for slaves and the poor. The pigeon population declined slowly from 1800 until 1870. As a result of more sophisticated capture techniques, the Passenger Pigeon population plummeted over the next 20 years with the last major harvest taken in 1896. These pigeons, once numbering in the billions, were hunted to extinction.

The Carolina Parakeet, the only parrot in eastern North America, went extinct because of deforestation and the killing of birds for use in ladies’ hats and for protection of fruit crops.

We know little about the extinction of the Labrador Duck. In all likelihood, the Eskimo Curlew and Bachman’s Warbler are extinct as well with humans having a significant role in their decline.

[originally published on April 21, 2008]

2008-06-04T11:36:00.002-04:00

Birds and Cat Mortality

As Earth Day approaches, I want to focus on the negative impacts that humans are having on our bird populations. Under the auspices of the Migratory Bird Treaty Act, 836 species of native North American birds are protected. Of those species, 78 are on the Endangered Species List and 14 more are listed as Threatened. Another 144 are listed as a Bird of Conservation Concern. Collectively, nearly a quarter of our bird species appear to be declining. The situation is probably even worse than we realize because we have very poor population data on many less common birds that are not currently listed as species of concern.

Some birds perish because of natural causes (for example, weather, predation by birds of prey, mammals or snakes, starvation, disease). But an awful lot of bird mortality can be attributed to human activities.

Without a doubt, the most significant impact humans are having on bird populations (and other flora and fauna as well) stems from habitat destruction or degradation. This habitat alteration has complex effects for migratory birds that require particular habitats for wintering, for stop-overs during migration and for nesting. It is hard to precisely gauge the impacts of habitat destruction on our bird populations. But added to deaths from natural causes, habitat alteration may be pushing some birds over the brink to local or even global extinction.

We have better measures of bird mortality from some human-related sources. Collisions of birds with buildings, mostly from flying into windows, claim nearly a billion birds a year. Collisions with cell phone and television/radio towers are responsible for five to 50 million avian deaths a year. Collisions with high tension power lines results in over 100 million bird deaths annually in the United States. Collisions with cars kill 60 million birds a year.

Over-use of pesticides can result in dramatic localized kills of birds. One recent estimate claimed that 72 million birds each year perish from exposure to pesticides. This estimate is surely low because pesticides may act slowly in a bird, resulting in death at a distance from a pesticide hot spot. Pesticides may cause neurological problems for birds, leading to death from starvation.

Cats are a potent source of mortality for birds. They have had devastating effects on some oceanic islands, leading to the extinction of some birds. In North America, we really do not have a good handle on the magnitude of the effects of cats on our birds. A recent study in Wisconsin demonstrated that domestic cats in the countryside kill 39 million birds in that state each year.

A recent article by Victoria Sims and her colleagues published in the journal Diversity and Distributions addresses the impact of cats on birds in urban areas in Britain. Only about 3% of cats in Britain remain indoors at all times.

Controversy reigns in Britain about the impact of cats on bird populations. One study claimed that cats account for a third of the deaths of local bird populations. On the other hand, skeptics argue that no conclusive studies have been done to demonstrate significant impacts of cat predation other than on oceanic islands.

When conducting a predator-prey study, an ecologist often begins by documenting the relationship between predator numbers and prey numbers. One expects to see a negative relationship: when predators are scare, prey density should be high; when predators are abundant, few prey will be found. In the field, such relationships between a cat predator and prey abundance have been found for lions, tigers and lynx. Domestic cats are a bit more complicated because they get some of their nutrition from the cat food that their owners provide.

In the Sims study, bird population numbers were obtained from Breeding Bird Survey (BBS) squares (each 1 km on a side) chosen randomly from across Britain. They focused their attention on 30 squares within urban areas. Within each of these urban BBS squares, they censused cats by door-to-door or telephone surveys.

The ornithologists found a positive relationship between the number of cats and the numbers of individual birds (the more cats, the more birds). This result suggests that cats are not having a significant predatory effect on birds. However, the authors claim that cats may have a strong impact in all of their study squares. The lowest cat density in a BBS square was 132 cats. One might expect to see higher bird densities in an urban study square with no cats. So, this study has shone some light on the controversy of the importance of cat predation on birds but is far from the last word.

[originally published on April 7, 2008]

2008-03-24T21:02:00.005-04:00

For the Birds - Maine Butterfly Survey; Short-stopped Migrations

Maine Butterfly Survey

The Maine Butterfly Survey, a five-year project to map the distribution and abundance of the butterflies and skippers of Maine, will kick off its second year this spring. This project relies heavily on volunteers. The first year yielded nearly 1000 records (specimens or photographs). The identification of the specimens is currently being confirmed by Reggie Webster, an expert in butterfly taxonomy.

Two volunteers photographed Pipevine Swallowtails in late September. These two records represent the first records of the species since 1907.

As the Volunteer Coordinator for the project, I would like to encourage you to participate in the project. All participants are asked to attend a training workshop. Each workshop participant will be given equipment, a handbook and voucher forms. The next workshop will be held on Saturday, May 3 at Colby College in Waterville. The workshop will begin at 9:30 and conclude around 2:30. Lunch will be provided. If you are interesting in attending the workshop, please email me to reserve a spot. Enrollment is limited.

The Scientific Method

Science provides us with one of the most powerful ways of understanding our world. The scientific method begins with observation of a pattern and then the creation of one or more hypotheses to explain the pattern. The next step is the collection of either experimental data or observations to try to disprove the hypotheses. If one hypothesis is not disproved, we accept it as tentatively true. A careful scientist will test the hypothesis with different experiments or observation. If the hypothesis still stands, she feels more confident of the hypothesis.
It’s easy to create hypotheses but it takes time and effort to test them. An untested hypothesis has no scientific validity. Nevertheless, a number of untested hypotheses to explain aspects of nature are treated as being true.

A recently published paper in the journal Behavioural Ecology tested an old explanation of why many butterflies and moths have circular patterns on their wings that look like the eyes of a vertebrate. Over 150 years ago, the suggestion was made that these eyespots mimic the eyes of the predators of the enemies of the butterflies and hence offer the butterflies some protection.

That explanation is quite plausible and in fact is a commonly cited example in animal behavior texts. But until now, it had never been tested. The researchers from Cambridge University crafted artificial moths out of paper and drew different kinds of markings on the models (bars, squares, eyespots, no markings). A small mealworm was attached to each moth model to tempt Blue Tits, Great Tits and House Sparrows.

The researchers found that artificial moths with eyespots were attacked as frequently as moths with bars or squares. The scientists found that more boldly marked moths, regardless of he shape of the markings, were avoided to a greater degree than lightly marked moths. Thus, the old explanation has been tested and found wanting. Predators avoid moths and butterflies with eyespots because they are conspicuous, not because they mimic a predator’s eyes.

Let’s continue this thread with some of my own research. Over the past decade, the concept of short-stopping has been applied to irruptive birds like northern finches and Red-breasted Nuthatches. The claim is that birds like Evening Grosbeaks and Purple Finches do not migrate as far south as they did 30 years ago because of the great increase in bird feeding over those 30 years. Thus, the hypothesis goes, Purple Finches use to need to migrate to North Carolina to find food in the winter but now can take advantage of the many sunflower seeds that New Englanders put out for the birds.

Like the eyespot hypothesis above, this short-stopping hypothesis seems like a reasonable one but was offered without a scientific effort to disprove it.

In 1999, I published a paper that tested this hypothesis. Specifically, I examined the irruptions of Common Redpolls. Purple Finches, Evening Grosbeaks, Pine Siskins, White-winged Crossbills and Pine Grosbeaks from eastern North America. I also examined Downy Woodpeckers, two species that do not migrate, as controls for my methodology. I divided the period from 1970 to 1990 into five-year intervals. Using Christmas Bird Count data, I found that irruptions of Evening Grosbeaks and Purple Finches extended further south in the earlier time periods. However, if irruptive birds are staying further north in more recent years, one would expect a corresponding increase in these irruptive birds in northern areas. I did not find such a pattern of increase and therefore my analysis failed to support the short-stopping hypothesis.

[Originally published on March 8, 2008]

2008-03-24T20:58:00.005-04:00

For the Birds - American Robin movements; Bird records

American Robins

A large influx of American Robins has occurred in Maine in the past couple of weeks. Some observers report flocks of 75 birds. The arrival of robins is often taken to be a sign of spring but don’t be fooled. These robins are almost certainly birds from the north that have been pushed south by lack of food. If you see a bunch of robins, take a close look at them. Some of them will likely have the dark back of the Newfoundland race of American Robins.

Most birds are remarkably tolerant of cold weather as long as they have sufficient food to support their increased metabolic demands in the winter. Common Redpolls can winter as in latitudes as high as 70 º N as long as they can find enough seeds. When seed production is low, they are forced to move south and we get to enjoy seeing these delightful sprites. Similarly, American Robins can tough out the winter in the Maritime Provinces and Newfoundland as long as sufficient fruit is available. When the fruit is depleted, the robins have no choice but to move south in search of food.

Owls

The heavy snowpack, and more importantly, the ice layers in the snow pack pose a huge challenge to our larger owls that depend on rodents and other small mammals for food. A number of birders have observed Barred Owls in the daytime in the past couple of months. Their daytime activity is almost surely a sign of the owls’ difficulty in finding food. The scarcity of available food makes it necessary for owls to forage both during the day and night.

At our feeding station in South China, we were treated to the presence of a Northern Saw-whet Owl. It was perching on a feeder pole, no doubt waiting for a vole or shrew to come out of snowpack to feed on some of the seeds that had fallen from the bird feeders.

Records

We certainly haven’t lacked for snow across the state this winter. Northern Aroostook County has been hit quite hard. As of this writing, Caribou has had 137 inches of snow this winter, 59 inches above normal, and is on a pace to set a new yearly snowfall record. With records on my mind, I thought a consideration of some bird records might be of interest.

The largest living bird is the Ostrich, a flightless bird that tips the scales at 345 pounds and reaches a height of nine feet. But that pride of place is unwarranted. The heaviest birds we know of were the elephant birds found in Madagascar until they went extinct around 1600. Those birds topped out at 1000 pounds. Their eggs had a two-gallon capacity and were in fact used as buckets by the Malagasy people. The tallest bird was one of 24 species of flightless moas found in New Zealand. Those were all exterminated by the year 1500. Dinornis means terrible bird, not a very fitting name for a leaf-eater.

How about the largest bird capable of power flight? That record belongs to the Great Bustard, a Eurasian grassland bird. Individuals may weigh as much as 46 pounds. However, the fossil record has even larger birds that we believe could fly under their own power. Four species of vulture-like birds called teratorns are known from North and South America, first appearing about 25 million years ago. The largest, Argentavis magnificens, had a wingspan of 26 feet. See the photograph at: http://farm2.static.flickr.com/1301/699750340_e5d88a64a1.jpg
At the other end of the spectrum, the smallest bird is the Bee Hummingbird found in Cuba. An adult weights only 1.6 grams, half the weight of a penny. Check out the picture of a Bee Hummingbird perched on a pencil eraser:
http://www.avianweb.com/images/birds/hummingbirds/bee.jpg

Humans are fascinated by speed records. For birds, the fastest speed ever measured was achieved by a Peregrine Falcon. The bird was in a stoop, making its body aerodynamically smooth and thus able to knife through the air with a minimum of friction. That diving bird was clocked at 117 mph!

It is appropriate that the speed record for flapping flight is held by a swift. The White-throated Needle-tailed Swift can achieve a speed of 107 mph. Red-breasted Mergansers are no slouches, though. These birds have been timed at 100 mph in level flight.

The birds that have the heaviest flight muscles relative to their body weight are the hummingbirds. That fact is not surprising because hummingbirds generate lots of power (upward lift and forward thrust) on the upstroke as well as the downstroke.

[Originally published on February 23, 2008]

2008-03-24T20:53:00.003-04:00

For the Birds - Highlights of Maine Christmas Bird Counts - III

This column is the last of three reviewing the highlights of some of the National Audubon Society Christmas Bird Counts for the 2007/2008 season. The six counts covered today span the breadth of our state.

We’ll start with the Misery Township Count, held on December 30. This count in the vicinity of The Forks south of Jackman has significantly colder weather than most of the other counts in the state. The species number and bird abundance for this circle are usually quite low but the potential for boreal species is high. This year’s count yielded 18 species. Highlights were three Bald Eagles, a Northern Goshawk, two Gray Jays, 75 Pine Grosbeaks and 30 Common Redpolls.
The remoteness of this count is indicated by the fact that a single Rock Pigeon was found. Also, the five American Crows were outnumbered by the 17 Common Ravens.

The most common species was Black-capped Chickadee with 124 birds found. No Boreal Chickadees were counted this year.

The Biddeford-Kennebunkport Count, held on December 29, produced a list of 79 species. Two Wood Ducks were the most unusual waterfowl among the 15 species of ducks and geese found. Northern Gannets put on a good show with 20 birds counted. Both cormorants were found, eight Great Cormorants and a single Double-crested.

Four species of diurnal raptors were counted with an American Kestrel being the most unusual for this time of year. Thirty-five Sanderlings were found on the beaches in the count circle and 39 Purple Sandpipers were on rocky headlands.

The alcid diversity was excellent with four species tallied: two Dovekies, a Thick-billed Murre, three Razorbills and three Black Guillemots.

Barred and Great Horned owls were detected this year. A northern flavor was imparted by the seven Northern Shrikes, three Bohemian Waxwings, and 22 Snow Buntings. Eight finch species were found with the three Red Crossbills, two White-winged Crossbills and three Evening Grosbeaks being particularly notable. Lingering birds from the summer included a Winter Wren, nine Eastern Bluebirds and a Brown-headed Cowbird.

The Monhegan Island count on January 3 yielded 46 species. Highlights included a Peregrine Falcon, a Dovekie, a Northern Shrike, three Carolina Wrens, a Yellow-rumped Warbler, a Fox Sparrow, a Rusty Blackbird and five Common Grackles.

The three counters found 11 Iceland Gulls and a Glaucous Gull to go along with the four Ring-billed Gulls, 80 Herring Gulls, five Great Black-backed Gulls and 54 Black-legged Kittiwakes.

Moving downeast, the Machias-Jonesport count on December 30 resulted in a final tally of 51 species. Four species of dabbling gulls were found. The nine Northern Pintails and single Green-winged Teal were excellent finds among the expected Mallards and American Black Ducks. Sixteen species of waterfowl were found in all. A single Barrow’s Goldeneye was a nice find.

Two Double-crested Cormorants lingered and none of our usual winter species, the Great Cormorant, were noted. The only birds of prey were 13 Bald Eagles and a Sharp-shinned Hawk.

A Tufted Titmouse was a good sighting as this species continues to expand into the middle third of our state. A Yellow-shafted Flicker was awfully late for this species; most depart the state by November.

Finch abundance was modest with only four species found: 46 Pine Grosbeaks, four Common Redpolls, three Pine Siskins and a lone American Goldfinch.

The final two counts, the Orono-Old Town count (December 15) and the Bangor-Bucksport count (December 29), are interesting to compare because of their proximity. These two counts yielded 49 and 50 species, respectively.

The Penobscot River is a good place for Barrow’s Goldeneyes in Maine. Orono counters found 25 to go along with 25 Common Goldeneyes. The Bangor counters found three Buffleheads, an unusual inland sighting for the winter in Maine.

Orono had five species of birds of prey including a Rough-legged Hawk and an American Kestrel. Bangor had three hawk species.

Bangor had an excellent sighting of a Red-bellied Woodpecker. Hairy Woodpeckers were more common than Downy Woodpeckers on both counts.

Two Northern Shrikes were found in Orono and three in Bangor. Tufted Titmice showed well with 32 in Bangor and 17 in Orono. Both counts had one Northern Mockingbird.

Orono had a fine count of 638 Bohemian Waxwings but that was dwarfed by the 2,016 Bohemians found in Bangor. A Common Grackle in Orono was late.

Pine Grosbeaks were the most numerous northern finch although both counts also had Purple Finches, Common Redpolls and Evening Grosbeaks.

[Originally published on February 9, 2008]

2008-03-24T20:49:00.003-04:00

For the Birds - Highlights of Maine Christmas Bird Counts - II

This column is the second of three reviewing the highlights of some of the National Audubon Society Christmas Bird Counts for the 2007/2008 count. We’ll examine three coastal counts in today’s column. I’ll cover them from south to north.

The Bath-Phippsburg-Georgetown Count, held on December 15, produced a list of 87 species. The number and diversity of birds associated with water were outstanding. Sixteen species of waterfowl were present. The 1,110 American Black Ducks was an impressive total. Other notable high counts were 792 Common Eiders, 160 Black Scoters, 368 Bufflehead, 28 Barrow’s Goldeneyes and 101 Hooded Mergansers.

Loons were found in good quantity: 79 Common Loons and 19 Red-throated Loons. The grebe family was represented by 49 Horned Grebes and 84 Red-necked Grebes.

Twenty Bald Eagles and 10 Red-tailed Hawks were found along with two Sharp-shinned Hawks, a Rough-legged Hawk and a Merlin.

Fifteen Dunlin and 34 Sanderlings were nice accompaniments to the 223 Purple Sandpipers. An unexpected shorebird was the singleton American Woodcock.

South of Cobscook Bay, Black-legged Kittiwakes tend to be found offshore at this time of year. With a bit of effort, kittiwakes can be seen from shore with a spotting scope. The Bath counters found 27 this year. An excellent sighting was a single Pomarine Jaeger, typically a pelagic species in Maine. In addition to the 28 Black Guillemots, six Razorbills added to the alcid diversity on this count.

Open countryside and coastal beaches attract a characteristic suite of ground-dwelling land birds. The Bath counters scored a grand slam with these species, finding 28 Horned Larks, one American Pipit, 113 Snow Buntings and one Lapland Longspur.

Lingering landbirds included a Northern Flicker, a Carolina Wren, a Hermit Thrush, a Yellow-rumped Warbler, three Red-winged Blackbirds, three Common Grackles and a Brown-headed Cowbird.

Irruptive species included six Bohemian Waxwings, 114 Pine Grosbeaks, three White-winged Crossbills and 27 Common Redpolls.

The Pemaquid-Damariscotta count, held on December 29, yielded a count of 55 species. Common Eider with 810 individuals was the most common duck found on the count. A single Harlequin Duck was a good find as was the single Barrow’s Goldeneye. A total of 97 Common Loons was tallied but no Red-throated Loons this time.

Six Bald Eagles were the only birds of prey on this winter’s count. Four species of gulls were found with the 657 Herring Gulls being the most abundant by far. The only alcids this year were six Black Guillemots and two Razorbills.

A Belted Kingfisher was a good find at this time of year. A Northern Flicker was the only other land bird that was lingering beyond the normal departure date for the species.

Irruptive species included a Northern Shrike and seven Bohemian Waxwings .

The finch diversity was outstanding with seven species counted, including 14 Pine Grosbeaks, one Purple Finch, a Common Redpoll, 12 Pine Siskins, 8 American Goldfinches and a fine count of 19 Evening Grosbeaks. A Red Crossbill was seen in the area just after the count.

The Schoodic count, held on January 3, produced a list of 46 species. Ten species of waterfowl were counted. The most abundant ducks were Common Eiders (305) and Buffleheads (309). A total of 24 Common Loons was found. Grebe numbers were modest with only 10 Horned Grebes and five Red-necked Grebes this year. Five Great Cormorants were recorded.

Only two raptors species were found this year. The raptors seen were eight Bald Eagles and two Northern Goshawks. Excellent quality if not quantity.

Purple Sandpipers, a wintering species in Maine on rocky shores, are notoriously patchy in their distribution. This year, Schoodic counters found only nine of these shorebirds.

Five species of gulls were found, highlighted by excellent counts of Iceland Gulls (six) and Glaucous Gulls (eight).

The Schoodic peninsula is dominated by coniferous forest. One would expect that Red-breasted Nuthatches, which prefer coniferous forest, would outnumber White-breasted Nuthatches, a species more associated with deciduous forest. That expectation was met with 12 red-breasts and 3 white-breasts tallied.

Tufted Titmice and Northern Cardinals have been expanding their ranges northward over the past 30 years. The downeast coast is at the frontier of this expansion. Schoodic counters found four Tufted Titmice and five Northern Cardinals.

Other notable records this year included a single Lapland Longspur and 124 Pine Grosbeaks.

[Originally published on January 26, 2008]

2008-03-24T20:47:00.002-04:00

For the Birds - Highlights of Maine Christmas Bird Counts - I

We are in the middle of the National Audubon Society Christmas Bird Count. As usual, the next columns will discuss the results of this important winter bird census in the United States, Canada and beyond. Until then, I thought it might be fun to think about the colorful language that has been used over the years to describe species of birds in North America.

Bluebill, baldpate, log-cock, high-hole, rain crow. These are all common names for different birds that are found in Maine. The common names used in different parts of the North America are being collected by an avian etymologist, Waldo McAtee. So far McAtee has found over half a million of these common names for our 800 species of birds.

The difficulty with common names is that confusion may arise over the particular species in question. For instance, the colloquial name of log-cock for the Pileated Woodpecker could reasonably be used to describe a Ruffed Grouse.

Biologists avoid the uncertainty of common names by using the standardized scientific name which consists of a genus name and a species name. However, most birdwatchers don't care to commit lots of Latin names to memory.

Fortunately, the Checklist Committee of the American Ornithologists' Union published a list of standard common names in 1957. The checklist is periodically revised to reflect increasing knowledge of bird classification. The common names used in field guides are the standardized common names. Use of these names rather than colloquial names reduces confusion. It is also a lot easier to say you saw three Blue Jays rather than three Cyanocitta cristata!

Some common names are descriptive and easily understood. For instance, woodpecker is a highly appropriate name for those birds which probe dead wood for insects. Flycatcher is another straightforward descriptive name. Other names are more obscure but interesting in terms of their word origin. I will discuss some of the less obvious common names of North American birds in the rest of today’s column.

Cormorants are often seen along the major rivers and on larger lakes in our region. Cormorant comes from two Latin words: corvus , meaning crow and marinus, meaning marine. So, cormorant is another way of saying sea-crow. Cormorants have little in common with crows besides their black plumage but the derivation of the word is charming.

Loon is an interesting term that is thought to derive from the Shetland word loom or the Icelandic word lomr. Both words mean lame and aptly describe the awkward walking of loons on land. The feet of loons are located near the rear of the body for efficient swimming but ungainly walking.

Hooded and Common Mergansers are frequently seen on larger bodies of water in our area. Merganser comes from two Latin words: mergus, meaning diver and anser, meaning goose. A perfectly apt description of these birds. One that is less appropriate is Bufflehead, a small diving duck that often is found with mergansers. Bufflehead is supposedly derived from buffalohead. It takes a little imagination to see the similarity of the heads of Buffleheads and buffaloes!

Falcon comes from the Latin falx, meaning sickle. The powerful bill of a falcon certainly bears a functional similarity to a sickle.

Gull comes from the Latin gula, meaning throat. Just like a person who is gullible, a gull will swallow anything!

Color may be the basis of the common name of birds. The Northern Cardinal is named for the high church official who wears a bright red robe. The Northern Oriole's name comes from the Middle Latin oriolus or the Latin aureolus, meaning golden.

The Eastern Kingbird is so named because of the small patch of red feathers on the top of its head that the male exposes when it is excited. The Ruby-crowned Kinglet is a much smaller bird but males have the same type of red crown as the kingbird.

We often say that birds chirp. This trait has given rise to at least two common names. The American Pipit, a bird that breeds on Mt. Katahdin and may be found in our state in agricultural fields in the spring and fall, has a name derived from the Latin pipo, meaning to chirp. The Swedish word siska means a chirper and gives us the common name for the Pine Siskin.

Finally some common names are based on the calls or songs of birds. Good examples of this type of common name are chickadee, whip-poor-will, cuckoo, curlew and towhee. The doleful call of the Mourning Dove gives this bird its name.

[Originally published on January 12, 2008]

2008-03-24T20:45:00.004-04:00

For the Birds - Etymologies of Common Names of Birds

We are in the middle of the National Audubon Society Christmas Bird Count. As usual, the next columns will discuss the results of this important winter bird census in the United States, Canada and beyond. Until then, I thought it might be fun to think about the colorful language that has been used over the years to describe species of birds in North America.

Bluebill, baldpate, log-cock, high-hole, rain crow. These are all common names for different birds that are found in Maine. The common names used in different parts of the North America are being collected by an avian etymologist, Waldo McAtee. So far McAtee has found over half a million of these common names for our 800 species of birds.

The difficulty with common names is that confusion may arise over the particular species in question. For instance, the colloquial name of log-cock for the Pileated Woodpecker could reasonably be used to describe a Ruffed Grouse.

Biologists avoid the uncertainty of common names by using the standardized scientific name which consists of a genus name and a species name. However, most birdwatchers don't care to commit lots of Latin names to memory.

Fortunately, the Checklist Committee of the American Ornithologists' Union published a list of standard common names in 1957. The checklist is periodically revised to reflect increasing knowledge of bird classification. The common names used in field guides are the standardized common names. Use of these names rather than colloquial names reduces confusion. It is also a lot easier to say you saw three Blue Jays rather than three Cyanocitta cristata!

Some common names are descriptive and easily understood. For instance, woodpecker is a highly appropriate name for those birds which probe dead wood for insects. Flycatcher is another straightforward descriptive name. Other names are more obscure but interesting in terms of their word origin. I will discuss some of the less obvious common names of North American birds in the rest of today’s column.

Cormorants are often seen along the major rivers and on larger lakes in our region. Cormorant comes from two Latin words: corvus , meaning crow and marinus, meaning marine. So, cormorant is another way of saying sea-crow. Cormorants have little in common with crows besides their black plumage but the derivation of the word is charming.

Loon is an interesting term that is thought to derive from the Shetland word loom or the Icelandic word lomr. Both words mean lame and aptly describe the awkward walking of loons on land. The feet of loons are located near the rear of the body for efficient swimming but ungainly walking.

Hooded and Common Mergansers are frequently seen on larger bodies of water in our area. Merganser comes from two Latin words: mergus, meaning diver and anser, meaning goose. A perfectly apt description of these birds. One that is less appropriate is Bufflehead, a small diving duck that often is found with mergansers. Bufflehead is supposedly derived from buffalohead. It takes a little imagination to see the similarity of the heads of Buffleheads and buffaloes!

Falcon comes from the Latin falx, meaning sickle. The powerful bill of a falcon certainly bears a functional similarity to a sickle.

Gull comes from the Latin gula, meaning throat. Just like a person who is gullible, a gull will swallow anything!

Color may be the basis of the common name of birds. The Northern Cardinal is named for the high church official who wears a bright red robe. The Northern Oriole's name comes from the Middle Latin oriolus or the Latin aureolus, meaning golden.

The Eastern Kingbird is so named because of the small patch of red feathers on the top of its head that the male exposes when it is excited. The Ruby-crowned Kinglet is a much smaller bird but males have the same type of red crown as the kingbird.

We often say that birds chirp. This trait has given rise to at least two common names. The American Pipit, a bird that breeds on Mt. Katahdin and may be found in our state in agricultural fields in the spring and fall, has a name derived from the Latin pipo, meaning to chirp. The Swedish word siska means a chirper and gives us the common name for the Pine Siskin.

Finally some common names are based on the calls or songs of birds. Good examples of this type of common name are chickadee, whip-poor-will, cuckoo, curlew and towhee. The doleful call of the Mourning Dove gives this bird its name.

[Originally published on December 29, 2007]

2008-03-24T20:38:00.005-04:00

For the Birds - Cyberbirding

It has been a while since I wrote about resources for birders and ornithologists on the internet. Today’s column will cover several innovations in cyberbirding. The Cornell Laboratory of Ornithology (hereafter, CLO) figures prominently in all of these resources.

The CLO has long been a depository for sound and video recordings of birds and other animals. Now that these files can be saved in digital format, they are easily shared with researchers and interested people.

The Macaulay Library of Natural Sounds at the CLO boasts the largest collection of sound recordings of animals in the world. Some of these sound recordings have associated video. The entire collection of recordings is currently being digitized. Currently over 65,000 sound clips and 18,000 video recording are available as streaming files for free.

The sound files can be played using the free application RealPlayer. Better yet, a free tool called RavenViewer can be downloaded. This tool works within QuickTime. RavenViewer not only allows you to play the sound recordings but to visualize the recordings in real time. A wave form of the sound scrolls across the screen showing the loud and soft portions of the file. Even more useful is the spectrogram that shows the frequencies of each part of the sound.
The sound and video recordings provide a great opportunity for learning. I searched for American Robin and found that 431 recordings are in the Macaulay Library, and nearly all have been uploaded for users to hear.

The focus of the on-line recordings is on North American species, mainly birds, although many recordings made outside of North America are available. To visit the Macaulay Library, go to: http://www.animalbehaviorarchive.org/

eBird

The CLO is maintaining a nationwide digital system for sharing birding observations. After a field trip, contributors simply visit eBird at http://ebird.org/ and enter the numbers of individuals of each species of bird they saw on a field trip along with the location. These records become part of a database that can be searched by anyone. Imagine you will be on a trip to Cleveland in April and want to know what birds you might be able to see. A quick search of the eBird database will give you tons of records of birds that other birds have seen in that area in the spring.

eBird keeps track of all the records you have added to the database and will keeps a lifelist for you. You can enter data taken from trips years ago. All of those records are valuable.

The eBird software knows when you have made an unusual sighting and will prompt you to make sure that other possible identifications have been eliminated. Rare bird sightings are tagged as such and can be sent to birders who like to keep abreast of local rarities.

The easiest way to keep track of these rarities is to use the eBird gadget (http://ebird.org/content/ebird/news/Google_Gadget.html). This is a tool that you load to a personalized iGoogle page (go to http://www.google.com/ig to set up the page). The eBird gadget will search the state of your choice for recent rarities. In looking at the eBird gadget list in my iGoogle page, I see that recent rarities in Maine are Eastern Screech Owl, Orange-crowned Warbler and Black-headed Gull. Directions and a map for the location of each sighting are provided.

Birds of North America

This project was born nearly 20 years when the Academy of Natural Sciences in Philadelphia devised a way to assess the cumulative knowledge of all North American breeding birds. A specialist was found to write an account for each of the over 700 species covered. Each account is in a standard format with the same organization throughout (e.g.,, Distribution, Distinguishing Characteristics, Migration, Habitat, Sounds,). One of the most valuable aspects of each account is the extensive bibliography on each species at the end of the account.

The 720 volumes were initially issued in paper. The accounts are now in digital format as well. One advantage of the digital accounts is that they can be easily updated as new information arises. A second advantage is that users do not need twelve feet of shelf space to house the collection.

The digital version of Birds of North America is administered now through the CLO (http://bna.birds.cornell.edu/bna). A yearly subscription is only $40.

The CLO has recently made an abbreviated form of each account available for free. This resource is called All About Birds. It can be found at: http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/ You can find links on that page to basic identification skills, bird gear and attracting birds to your backyard.

[Originally published on December 15, 2007]

2008-03-24T20:31:00.002-04:00

For the Birds - Gift Recommendations

The holiday gift season is upon us. Several people have asked me for gift recommendations for birders. I thought I might share some suggestions in today’s column.

All birders need a field guide and my favorite is the Sibley Guide to Birds. This guide covers all the birds recorded in North America and multiple illustrations are provided for most species. A downside of the Sibley Guide is its size, far too large to fit in a coat pocket for easy carrying in the field. To make a more portable guide, the Sibley Guide has been reconfigured into two smaller, pocket-size guides. One is for birds of eastern North America and one for the western part of our continent. The portable guides do not have all of the illustrations or text of the large Sibley Guide.

The Sibley Guides are not the only field guides to North American birds and I recommend that birders own several different field guides. Each will have information that others lack. The National Geographic Field Guide to the Birds of North America has just been published in its fifth edition. This guide covers all the birds of North America but is much more smaller and portable than the original Sibley Guide.

People on your gift list who are just beginning to get into birding might appreciate a copy of the Peterson Guide to the Birds of Eastern North America. Roger Tory Peterson’s arrow system, in which critical field marks are indicated on his excellent illustrations, is helpful for beginning to intermediate birders.

Peterson, who passed away in 1996, was one of the most influential figures in bird identification in the 20th century. From 1984 until his death, he wrote a bird column in the Bird Watcher’s Digest. The best of those essays have been collected in a book called All Things Reconsidered: My Birding Adventures. The essays are great fun to read and the book is a real bargain.
Bernd Heinrich’s Ravens in Winter is a scientific detective story. Heinrich, a retired biology professor at the University of Vermont, owns a large tract of property in Maine near Mount Blue State Park where he has done much research over the years. The mystery concerns a Common Raven that discovered a moose carcass. Ravens depend on carcasses for much of their nutrition during the winter and this moose was a veritable bonanza. But instead of taking advantage of the food, the raven flew widely over the woods, calling vigorously. The raven was announcing the find to other ravens. The party was on! Heinrich could not understand why the original discoverer would be willing to share. Why was this raven an altruist? Wouldn’t it be better for the discoverer to keep the location of the carcass secret?

Ravens in Winter is a recounting of the blind alleys and fruitful avenues that Heinrich took to ultimately solve the mystery. The book is a fine recounting of the way that science is conducted.

Ravens are considered some of the most intelligent birds. In a subsequent book, Mind of the Raven, Heinrich explores the behavior of Common Ravens in Maine and beyond. He recounts many of his own experiments and observations, supplemented by summaries of the work of other raven researchers. The reader comes away with great appreciation for the intelligence of the “wolf-bird”.

For people who want an authoritative treatment of the field of ornithology, Ornithology by Frank Gill and Handbook of Bird Biology, written by a number of ornithologists at the Cornell Laboratory of Ornithology, will fit the bill. The Handbook comes with a CD of bird vocalizations, discussed in the book.

I have four recommendations for DVD’s. Each is beautifully filmed and heart-warming in its own way. March of the Penguins describes the incredibly arduous reproduction of Emperor Penguins in Antarctica. The film clearly depicts the remarkable adaptations these penguins have to allow them to survive and reproduce in the deep Antarctic cold.

Winged Migration is a visual delight with a minimum of narration. Using ultralight aircraft, the videographers filmed cranes, geese and other birds in flight. Footage comes from a number of locations, from Antarctica to New York City to equatorial South America.

The Wild Parrots of Telegraph Hill is a documentary of the relationship between Mark Bittner, a homeless musician in San Francisco, and a flock of released parrots. You will come to know many of the parrots. It is a love story in more ways than one.

Finally, consider giving David Attenborough’s Life of Birds DVD collection to a birding friend or family member. This set has ten hours of superb footage of all aspects of the biology of birds. Don’t miss the footage of the Superb Lyrebird that mimics a camera shutter and a chain saw!

[Originally published on December 1, 2007]

2007-12-13T13:00:00.000-05:00

For the Birds - Northern Finch Forecast

In the last column, I wrote about irruptive northern finches. In the past two weeks, birders across Maine have seen an influx of some of these birds. Common Redpolls, Pine Grosbeaks, Evening Grosbeaks, Pine Siskins, Red Crossbills and White-winged Crossbills have all been seen at multiple locations in the state.

I pointed out that two events must occur for significant irruptions to occur. First, the seed crop on the breeding grounds of these northern birds must be low, forcing the birds to move south for the winter. Second, our seed crops must be sufficient to provide for irrupting birds and allow them to stay. It is already clear that this will be a flight year for northern finches. Will we have enough seeds here to support the finches for the winter? We’ll have to see.

Ron Pittaway, an Ontario birder, gathers information on seed crops in eastern Canada and prepares a prediction for northern finch abundance. Some of the information Ron uses comes from eastern Quebec and the Maritime Provinces so his predictions can be applied to Maine with a bit of caution.

As one would surmise from the northern finches already arriving in Maine, seed crops in the boreal forests of Canada are poor this year. Last year by the way produced bumper crops of conifers in the boreal forest and northern finches were scarce as hens’ teeth here in Maine last winter.

Ron notes that in Ontario Pine Siskins and White-winged Crossbills departed east and west in the summer. This eastward movement may account for the good Pine Siskin numbers we have seen in Maine this fall. Bird counts in Ontario indicate that Evening Grosbeaks, Pine Grosbeaks, Purple Finches and redpolls (Common Redpoll and the much rarer Hoary Redpoll) are irrupting south from northern Ontario. Bring them on!

Pine Grosbeaks are unusual finches because they depend largely on soft fruit rather than seeds of conifers or other trees. Pine Grosbeak movements are triggered by failure of mountain ash (or rowan trees). Poor fruit set has occurred in the boreal forests of Canada. Irrupting Pine Grosbeaks look for crabapples, mountain ash berries and the fruits of various ornamental shrubs like cherries. They will also frequent sunflower seed feeders. We have not had a sizeable Pine Grosbeak flight since the winter of 2001/2002.

Purple Finches have been driven south out of northern Ontario by low conifer production. Ron Pittaway predicts that the Purple Finches will continue to move south into the mid-Atlantic states as fall gives way to winter. If he is right, enjoy those Purple Finches at your feeder while you can.

White-winged Crossbills are one of the most nomadic of the northern finches, wandering frequently in search of good cone crops. Once a bumper crop is found, these crossbills may stop and nest, regardless of the season. White-winged Crossbills are the only North American birds in which nesting has been documented in every month of the year. One of my most memorable birding memories occurred in the Northeast Kingdom of Vermont one January when I watched White-winged Crossbills feeding their young when the temperature was twenty below!

Pittaway notes that the favored cones of White-winged Crossbills, balsam fir and red spruce cones, are scarce throughout Ontario but abundant in Nova Scotia. My impression is that Maine crops of these two trees are good as well. Perhaps we will have a banner year for White-winged Crossbills.

Birch seeds, the favored food of Common Redpolls, are quite scarce throughout northern Ontario and Quebec. There is every reason to believe we will have an excellent winter for Common Redpolls this year.

Evening Grosbeaks depend on seeds from a variety of trees, most of which have a poor seed crop this year in the boreal forests of eastern Canada. We can expect an irruption but unfortunately nothing like the irruptions of 20 years ago. Evening Grosbeaks populations are declining and the likely reason is the decline of spruce budworms. Evening Grosbeaks rely on spruce budworm caterpillars and pupae for feeding their young. So the lack of major spruce budworm outbreaks has been great for spruce trees but unfortunate for Evening Grosbeaks.

Irruptions are also staged by Red-breasted Nuthatches and Bohemian Waxwings. Red-breasted Nuthatches depend on cone seeds for overwintering and not surprisingly have moved south (some as far as Georgia). They are pretty common in Maine now.

Like the Pine Grosbeaks, Bohemian Waxwings depend on mountain ash berries. The poor yield of these trees in the boreal Canadian forests is forcing these vagrants south and east. Good numbers have already been seen in Maine.

[Originally published on November 17, 2007]

2007-12-13T12:58:00.000-05:00

For the Birds - Northern Finch Irruption

For the past two months, a flock of Purple Finches has been frequenting our feeders in South China. This species seems to be pretty common throughout Maine so far this fall. Over the weekend, the Purple Finches were joined by a voracious flock of Pine Siskins. Many other Maine birders have recently reported siskins as well.

Purple Finches and Pine Siskins are two species in a group of finches commonly called the northern finches. Others in the group are Common Redpolls, Hoary Redpolls (quite uncommon in Maine), White-winged Crossbills, Red Crossbills, Evening Grosbeaks and Pine Grosbeaks.

These species nest at higher latitudes. The two redpolls and Pine Grosbeak nest to the north of Maine. Although the other five species are known nesters in our state, most of their nesting occurs to the north of us.

The northern finches are well known for their winter irruptions. An irruption is the opposite of an eruption. Birds erupt or leave from one area and irrupt or arrive in a different region. In good irruption years, we may be thrilled by large numbers of Common Redpolls or Pine Grosbeaks at our feeders and crossbills in the coniferous woods.

The cause of this irruptive behavior is food. All of these northern finches are primarily seed-eaters and many feed primarily on the cones of spruces, firs, tamaracks, hemlocks and even pines. Common Redpolls depend heavily on birch seeds for their winter sustenance.

We know that cone or seed production by trees in a local area varies greatly from year to year. A year of heavy seed production, called a mast year, may be followed by several years of low seed production. This annual variability seems to be an adaptation by trees to reduce the effect of insect seed predators.

By producing relatively few seeds for several years in a row, the trees keep the insect seed predators at a fairly low population size although most of the seeds produced may be eaten by the insects. Then a mast year occurs and seed production is so high that the insect population cannot consume all of the plenty. At least some of the seeds will successfully disperse and germinate. Of course, the insect populations will rise but are sure to plummet the following year when seed production is low.

The northern finches travel broadly in search of appropriate trees having a mast year. For us, two conditions must occur for an irruption to occur. First, our trees must be having a mast year to attract and hold any irrupting birds. Second, the trees on the nesting grounds of the northern finches must have a year of low seed production, forcing the finches to erupt elsewhere in search of sufficient seeds. So, a mast year in Maine may not always be accompanied by a northern finch irruption.

When I was growing up in North Carolina, we would often be delighted by hordes of Evening Grosbeaks and Pine Siskins during the winter. Those irruptions are events of the past. Big flights of Evening Grosbeaks are now uncommon even in Maine.

It occurred to me a few years ago that the rise of bird-feeding over the past 25 years might be influencing the irruptions of northern finches. Perhaps, Pine Siskins and other finches do not need to go so far south now to find natural food because of all of the sunflower and niger seeds we put out for them. In other words, I wondered if northern finch irruptions were being short-stopped.

To test for a short-stopping effect of bird feeding, I analyzed all of the recapture data of banded birds for six northern finches (Common Redpoll, Purple Finch, Pine Siskin, Pine Grosbeak, Evening Grosbeak and White-winged Crossbill) in eastern North America from 1975-1994. I also used Christmas Bird Count data for the same years as a measure of how the magnitude of irruptions of these birds might have changed.

I was able to show that larger irruptions occurred earlier in the study (pre-1984). However, recapture of banded birds showed that there was no significant increase in finches wintering at northern latitudes over time. The data suggest that the less dramatic irruptions in recent years are due to a decline in the populations of these birds rather than a short-stopping of irruptive movements.

What will this winter bring? Perhaps Pine Siskins will stage a large irruption this year. Common Redpolls in Maine have shown a strong pattern of alternating an irruption year with a year of few individuals. We should be in for a Common Redpoll irruption this winter.

[Originally published on November 3, 2007]

2007-12-13T12:55:00.000-05:00

For the Birds - Review of "Of a Feather" by Scott Weidensaul

I’ve must finished reading a new book by Scott Weidensaul called “Of a Feather: A Brief History of American Birding”. It’s a delightful read and I offer this review to you today.

I have reviewed other books by Weidensaul, one of our most gifted nature writers, in this column before. His books include “Living on the Wind”, a lyrical examination of bird migration and “Return to Wild America” in which he retraced the trans-North America birding trip that Roger Tory Peterson and his British friend, James Fisher, had done 50 years before.

Weidensaul lives in the mountains of Pennsylvania but has a Maine connection. He is one of the instructors in the summer National Audubon Camp on Hog Island off mid-coastal Maine.

In “Of a Feather”, Weidensaul gives a whirlwind tour of the history of bird study in the United States and Canada. Birding is now a popular avocation in North America. Six million U. S. citizens can identify at least 20 species of birds. The sale of bird seeds, binoculars and associated materials along with money spent on traveling to see birds give birding a significant economic influence. That was not always the case of course.
The first portion of the book is devoted to the period of discovery when to European eyes the birdlife of North America was new and undescribed. This period begins with John White, a member of the Roanoke Colony or Lost Colony in Manteo, North Carolina from 1585-1587. White’s charge was to paint every kind of living thing that was not known in England.

The two notable students of birds in the 18th century were John Lawson and Mark Catesby. Lawson was a surveyor and land speculator with a strong interest in natural history. He published a book in 1709, “A New Voyage to Carolina”, detailing the 136 species of birds he saw on a two-month journey to the Carolinas.
Catesby built on Lawson’s work, sometimes plagiarizing his material, in his “The Natural History of Carolina, Florida, and the Bahama Islands”. This book was published in installments, with each installment containing 20 colored plates. This book is considered the first ornithological text on American birds.

The age of ornithological discovery continues with two luminaries, Alexander Wilson and John James Audubon. Neither of these men had any formal biological station but were captivated by birds.

Wilson, a Scottish immigrant, arrived in the New World when was 28 years old. He saw a copy of Catesby’s book in the library of the naturalist William Bartram and was inspired to build on Catesby’s work. Wilson traveled widely in eastern North America and published the first comprehensive account of North American birds, “American Ornithology”. This work, also published in installments, contained many accurate paintings of eastern birds, including 26 that were new to science. “American Ornithology” covered 268 species of the 350 species that we know occur in the region Wilson surveyed.

Audubon was clearly a more skilled artist than Wilson but seemingly a less reliable observer. Weidensaul does a fine job of pointing out the foibles and failings of Audubon as well as his lasting contributions to ornithology. Understanding the man was made more difficult by his granddaughter who altered Audubon’s diaries and letters after his death to mask his egotism. Nonetheless, few will argue that Audubon’s paintings are masterful and a tremendous improvement on the paintings of North American birds done by his predecessors.

Wilson and Audubon met briefly in a store in Louisville that Audubon and a partner owned. Wilson showed Audubon some of his paintings and Audubon nearly subscribed until his partner pointed out that Audubon’s own paintings were superior to Wilson’s.

The age of discovery continued in the 19th century with westward exploration, beginning with the Lewis and Clark expedition. Some of the greatest contributions were made by military officers, often medical doctors, who were stationed at forts in the west. A number of western birds have common names that commemorate such men as Bendire, Baird, Hammond and Xantus.

The end of the 19th century resulted in two distinct paths of bird study. The American Ornithologists Union was founded in 1883. This professional organization advocated the collection of bird specimens. People with an avocation in birds cut a second path that resulted in conservation groups like the National Audubon Society and the rise in the use of binoculars rather than shotguns to identify birds. More recently, the American Birding Association continues the tradition of bird study by amateurs.
I’ve managed to only touch the surface of the rich birding history that Weidensaul chronicles in his fine book.

[Orginally published on October 6, 2007]

2007-12-13T12:51:00.000-05:00

For the Birds - Fall Migrant Flight Calls and Seabirds

Flight calls of migrating birds

Fall migration is well underway now. You no doubt have noticed birds in the morning that weren’t there the day before. A great way to experience the fall migration is with your ears. Go out on a clear night with little wind. Shortly after dusk you will be able to her the chip notes of unseen migrants above. On a good night, a river of birds will pass over, with most individuals giving away their presence with distinctive flight calls. The migrant river may flow all night although much of the migration occurs before midnight.

Just hearing the migrating birds is thrill enough. However, it is possible with practice to identify migrating birds by their characteristic notes. Some species give flight calls that are similar or even identical to call notes they give on the ground. Others, like the thrushes, have distinctive flight calls that are only given while in flight. A great resource for learning these calls is a CD-ROM titled Flight Calls of Migratory Birds, put together by Bill Evans and Michael O’Brien. The CD has recordings of the flight calls of 211 eastern landbirds. You can find more information at: http://www.oldbird.org/. The website also gives directions on making an inexpensive recording apparatus using such high-tech equipment as plastic flower pots, a plastic dinner plate and saran wrap. Another site with some recordings of flight calls can be found at: http://www.birds.cornell.edu/birdcalls

Seabirds

Fall is a great time to look for seabirds in the Gulf of Maine. The term seabird does not refer to a particular taxonomic group of birds but rather to birds that spend most of the year on or above the ocean well out of sight of land. All of the tube-noses (albatrosses, shearwater, storm-petrels) are seabirds. Northern Gannets and their relatives are properly called seabirds. Some sandpipers, the Red Phalarope and Red-necked Phalarope, are seabirds. Among the gulls, Sabine’s Gulls and Black-legged Kittiwakes to a lesser degree are encountered only offshore outside of the breeding season. Skuas (two species in Maine) and jaegers (three species in Maine) are gull relatives that typically occur on open water for most of the year. Five of the six species of auks that nest in the western Atlantic (Atlantic Puffin, Razorbill, Common Murre, Thick-billed Murre and Dovekie) winter at sea. The Black Guillemot is our only auk that can be reliably seen from shore in every month of the year.

The seabird community of the Gulf of Maine is an interesting mix of species like Atlantic Puffin that nest abundantly from Newfoundland south to Maine, species like the Dovekie that nest at high latitudes and the jaegers that nest broadly on the arctic tundra. Leach’s Storm-Petrels nest along the shores of the Gulf of Maine while the similar Wilson’s Storm-Petrel breeds in the southern oceans and disperses to the northern hemisphere during the austral winter. Our two most common shearwaters, Greater Shearwater and Sooty Shearwater, also nest in the southern hemisphere.

There are several ways that you can see some of these seabirds. One easy way is to go on a whale-watching cruise. These boats go offshore far enough to find whales and that is usually far enough to see seabirds. A second option is to take a ferry ride aboard the Cat from Bar Harbor to Yarmouth, Nova Scotia. By crossing the Gulf of Maine twice you will have great chances to see many of our seabird species.

Maine Audubon offers an annual seabird trip out of Bar Harbor. This year’s trip will be on September 29 from 6 AM until 2 PM. The boat used this year will be a fast 110-foot power catamaran so a lot of territory can be covered. Contact Margi Huber (mhuber@maineaudubon.org) for more information.

[Originally published on September 22, 2007]

2007-12-13T12:45:00.000-05:00

For the Birds - Hoarding

Today we will begin with some wisdom of the ages as given in one of Aesop’s fables, The Ant and the Grasshopper. This lesson is particularly relevant as summer wanes and cool fall weather will soon enough lead to the cold of winter.

“In a field one summer's day a Grasshopper was hopping about, chirping and singing to its heart's content. An Ant passed by, bearing along with great toil an ear of corn he was taking to the nest. "Why not come and chat with me," said the Grasshopper, "instead of toiling and moiling in that way?"

"I am helping to lay up food for the winter," said the Ant, "and recommend you to do the same."

"Why bother about winter?" said the Grasshopper; we have got plenty of food at present." But the Ant went on its way and continued its toil. When the winter came the Grasshopper had no food and found itself dying of hunger, while it saw the ants distributing every day corn and grain from the stores they had collected in the summer. Then the Grasshopper knew: It is best to prepare for the days of necessity.”

Quite a number of birds follow the ant’s advice and put food away for seasons of scarcity. Winter poses a particular challenge for Maine birds. Insects are virtually absent, snow covers lots of potential food and the days are so short that birds have little time to find enough food to last them through the night.

Black-capped Chickadees provide an excellent example of food-hoarding behavior. Usually seeds are hoarded although insects and spiders may be stored as well. Insects and spiders are prepared before storage by removing the head. Chickadees readily cache sunflower seeds and pieces of suet from bird feeders. You have probably seen this behavior at your own feeders. A chickadee will remove the husk of a seed before caching it.

Chickadees do most of their hoarding in the fall. The number of seeds stored is staggering. Over a thousand items may be stored in a single day and, over the course of autumn, 50,000 to 80,000 spruce seeds were stored at one study site.

Sites for food storage are varied. Typical hiding places are cracks or crevices in woody vegetation, under bits of bark (particularly birch bark), in clusters of conifer needles, in the ground and even in the snow.

An interesting pattern emerges when one compares the frequency of hoarding in different parts of the range of Black-capped Chickadees. Hoarding is frequently noted in northern populations, as reported in studies done in upstate New York and Ontario. In milder climates like southern Illinois, food caching is rarely seen. Chickadees there seem to be able to get away with the grasshopper strategy!

Unlike some birds that hoard food at a single location, chickadees store their food in widely scattered locations. The advantage of scattering hiding sites is that other chickadees will not be able to steal all of their stored food if a thief encounters a stored seed. The disadvantage, of course, is the need to remember where all the seeds are stored.

The spatial memory of chickadees has been a productive and exciting area of ornithological research. Research done at the University of Toronto clearly showed that chickadees can remember their hoarding sites 24 hours after storage. Chickadees also spent little time at sites where food had been removed, either by the chickadee that stored the food or by a thieving chickadee that stole the cache.

Remembering where food is stored for a day is impressive but what benefits does such short-term memory give for a chickadee on a cold February day. Recent research indicates that chickadees have a longer-term memory for food. Chickadees were able to find food 28 days after caching it. To make matters difficult for researchers, chickadees are also known to take a hoarded seed and then store it somewhere else!

Neurobiologists have shown that a particular region of the brain called the hippocampus is important in spatial memory in chickadees. Birds in which the hippocampus is damaged are less capable of finding hoarded seeds.

Comparisons of the size of the hippocampus in different types of birds is intriguing. The hippocampus in bird species which hoard food is proportionally larger compared to species, which do not hoard.

Within a chickadee, the size of the hippocampus changes throughout the year! The hippocampus is relatively small in the spring but significantly larger in fall as the bird begins to hoard food (and, one hopes, remembers where it was hoarded).

[Originally published on September 8, 2007]

2007-09-16T18:47:00.000-04:00

For the Birds - Chimney Swifts

One of our most distinctive breeding birds is the Chimney Swift. Swifts are wonderfully agile fliers with long, curved wings. They have short, tapered tails leading some authors to refer to them as flying cigars. Swifts have a distinctive stiff-winged flight. The wings of a swift appear to beat alternately but actually beat in unison like all other birds.

Chimney Swifts spend most of their time during the day in flight, hawking insects. Swifts have amazingly large mouths that serve them well in capturing insects on the wing. Their method of feeding brings to mind the feeding of swallows but swifts and swallows are not closely related. Believe it or not, swifts’ closest relatives are hummingbirds.

Chimney Swifts give away their presence by their near constant twittering. You can hear a recording of these sounds at: swift vocalizations.

The genus to which the Chimney Swift belongs is Chaetura. Chaetura means “bristle tail” and refers to distinctive hair-like bristle feathers that occur at the base of the tail. The function of these bristles is not known.

Chimney Swifts generally return to central Maine in early May. Their twittering is nearly incessant then as courtship begins. Initially, four to seven swifts fly together in an oval or circular path. Then, three birds will fly together with one acting as the leader, flying ahead of the other two. Finally, two birds will court each other by flying very close together with one bird slightly lower than the second.

Faithfulness to a mate varies. In one study in Ohio, one female had the same mate for nine consecutive years. In that same study, another female had seven different mates over the nine-year period.

Before human habitations dotted the eastern landscape, Chimney Swifts nested in hollow trees and in caves. Now, virtually all Chimney Swifts nest in house chimneys. We have pretty good evidence that Chimney Swifts were widely distributed but uncommon before Europeans settled across eastern North America. The chimneys present in virtually every colonist’s house allowed for an increase in the Chimney Swift population. This information strongly suggests that nesting sites limited the population before houses began to dot the landscape.

Both mom and dad contribute to the construction of the nest inside a chimney. The nests are semicircular cups made of twigs, attached to a vertical portion of the chimney. The swifts gather the twigs on the wing with their feet and usually transfer the twigs to their bill to carry them back to the nesting site. The twigs are glued together with the sticky saliva that the birds produce from their hyperactive salivary glands. After the nest is built, the parents’ salivary glands shrink rapidly.

A Chimney Swift nest usually has four eggs; some nests may have as many as six eggs. Both the female and the male incubate the eggs; hatching takes place 18 to 21 days after incubation commences.

Occasionally, an unmated helper will assist a pair in raising the young. The importance of the third “parent” on fledging success is not known. In most bird species in which cooperative breeding occurs, the helpers are related to the papers but we don’t know if that is the case for Chimney Swifts.

By the way, the Asian delicacy, bird nest soup, is made of the nests of cave swiftlets. The swiftlet’s nest is made of pure hardened saliva.

Both parents feed the young. Sometimes, unmated individuals will assist a pair in feeding their young. Chimney Swifts are diligent parents, sometimes foraging at night to obtain food for their hungry young. Chimney Swifts raise only one brood per year.

As Chimney Swifts prepare to migrate, they often spend the night in large communal roosts. It is truly a spectacle to see 100 or more Chimney Swifts at dusk funneling into a chimney.

Swifts have an unusual arrangement of their toes, a clear adaptation to perching on vertical surfaces. A swift can point all four of its toes upward to maximize its ability to cling to a vertical surface. Ornithologists refer to such digits as pamprodactyl toes.

However, gravity is a force that is difficult to resist and sometimes swifts fall down chimneys into a homeowner’s fireplace or woodstove. If the swift is capable of flight, the bird will fly around and eventually perch on a vertical surface like curtains or even the wall. You can then slowly approach the perched swift with a coffee can, trash basket or other small container and cover the swift. Slip a piece of cardboard over the opening of the container. Take the swift outside and let it go.

[Column originally published on August 24, 2007]

2007-09-16T18:38:00.001-04:00

More on Hair Gathering by Tufted Titmouse

In response to the previous column on Tufted Titmouse hair gathering, Nancy King of Standish wrote to say that a Tufted Titmouse took hair from her own head. The titmouse gathered some hair from Nancy's hair over a three-day period every time Nancy came out on her deck.

2007-09-16T18:29:00.000-04:00

For the Birds: Tufted Titmice and New Gull Book

Cheeky Titmouse

As the 2007 nesting season ends for most of our birds, I want to share a remarkable story of a Tufted Titmouse in Richmond, Maine reported to me by Alice Elliott. Alice and her husband Dan own a golden retriever named Fisher.

Tufted Titmice often incorporate hair into their nests, particularly the inner lining. Last April, Alice and Dan were amused to see a Tufted Titmouse land on Fisher while he was sleeping on the deck. It soon became clear that the titmouse was pulling hair from Fisher to use in nest construction. Fisher was amazingly tolerant as the titmouse removed large beakfuls of hair.

The titmice started a second brood later in the summer and came back to the patient Fisher for more hair.

You can see photographs of the titmouse and Fisher at Alice’s blog (http://henbogle.blogspot.com/). Go to the April 25 post to see a number of photographs of the titmouse removing Fisher’s hair. Go to the July 25 post to see a short video of this unlikely pair.

New gull book

Houghton Mifflin has recently published a new gull identification guide. Written by Steve Howell and Jon Dunn, the book is titled Gulls of the Americas. The book is in the Peterson Reference Guide series. At a size of seven by ten inches, the book will be used more in studying at home rather than serving as a field guide.

This book is a potent competitor to Gulls of North America, Europe and Asia published in 2003 by Klaus Olsen and Hans Larsson. Howell and Dunn’s book covers gulls in North and South America; South American gulls are not covered in Olsen and Larsson.

Gulls are challenging birds to identify in the field. Our smallest gulls require two years to acquire adult plumage and our largest gulls take four years. Within a population, significant variation in appearance and in the onset of molting creates a bewildering variety of gulls. Gulls often roost and forage in mixed flocks, adding to identification challenges. Geographic variation across the range of many species adds to the confusion. Finally, gulls hybridize to make matters even more complicated.

Careful study of Howell and Dunn’s book will reward any birder. They begin their book with an introduction to gull morphology and molting. Little information is provided on behavior, reproduction and foraging of gulls; the book is focused on identification.

The introduction is abundantly provided with high-quality photographs. Many of the photographs are labeled to show features like the gonydeal expansion, primary projection and tertial crescent that can be important features in identification.

The authors provide a lucid description of molts and plumages. Rather than writing of molts in terms of years, they consider molts in terms of cycles. A cycle begins when a gull begins a molt that includes replacement of all of its primary feathers. For adults, a cycle corresponds to a year. Adult gulls usually begin their flight feather molt in the late summer after breeding. For cycles of immature birds, molting usually takes several months less than the adult cycle. For these birds, years and cycles do not match so gull researches choose to identify plumages as second-cycle, third-cycle, etc.

As a way to reduce the identification possibilities of a gull, the authors divide the gulls into two groups, the Tern-like Gulls and the typical gulls. The Tern-like gulls are the smaller gulls with more buoyant flights. This group includes Bonaparte’s Gull, Little Gull and Black-legged Kittiwake. Herring Gull and Ring-billed Gull are Typical Gulls. They further subdivide each of these two major groups into smaller groups. Most of these sub-groups seem reasonable although I question why they put Bonaparte’s Gull and Black-headed Gull in the Masked Tern-like Gulls and put Little Gull in a separate category, Small Tern-like Gulls. Bonaparte’s Gull is scarcely larger than Little Gull and separating these two species in the field is a challenge.

Following the introduction is the largest section of the book, the Plates. The authors devote 250 pages to annotated photographs of the various species and hybrids of gulls. Each page has up to six photographs. The photographs show the variation within species and cycles for the 36 gull species.

The remainder of the book is devoted to textual Species Accounts. Each account begins with an Identification Summary followed by a section on Status and Distribution. Most of the account is devoted to Field Identification in which each cycle is thoroughly described. Flipping between the Species Account and the appropriate pictures in the Plates is an effective way to improve one’s gull identification skills.

[Column originally published on August 10, 2007]

2007-08-20T10:13:00.000-04:00

Maine Bird Tour - III

On June 21, we drove from our B&B in Lubec to the dock in Cutler for a 7 AM departure on a puffin cruise aboard the Barbara Frost to Machias Seal Island, part of the province of New Brunswick. A thick fog that so often besets the coast here at the lower portion of the Bay of Fundy delayed us for a bit but soon enough we were wending our way out of the harbor for the ten mile cruise to the island.

The fog had lifted enough along the way to allow us to see quite a few Northern Gannets and the occasional Wilson’s Storm-Petrel. Machias Seal Island was shrouded in fog but we knew we were getting close because of the many Atlantic Puffins and Razorbills that began flying by the boat.

Fifteen of us were ferried ashore in a small dinghy and scrambled up the rocks to the lighthouse on the island. A Canadian Wildlife Service biologist gave us the do’s and don’t’s about the island. We then divided into four groups, each group going to one of the four photographic blinds right on the rocky shore. The fog was lifting and soon we were enjoying blue skies and great visibility.

These blinds provide an unbelievable opportunity to observe and photograph the Atlantic Puffins, Razorbills and Common Murres that nest on the island. The birds are literally only a few feet away. The puffins often land right on top of the blind. It’s pretty neat to hear puffins doing the two-step right above your head!

We had over an hour in the blinds until another tour group arrived. We could have stayed twice as long.

The 20-acre island is mostly vegetated by short grasses. A few Song Sparrows and Savannah Sparrows were singing from the meadow. An unexpected find was a Black-billed Cuckoo.

Historically, several thousand Arctic Terns have nested on the island. These aggressive birds dive-bombed human visitors as they walked to and from the blinds. This year the terns abandoned the nesting site for unknown reasons. Only a few terns were flying around.

Although there are four Maine islands where you can see puffins (Seal Island, Petit Manan, Matinicus Rock and Eastern Egg Rock), landing is not permitted. Two Maine companies offer cruises to Machias Seal Island, the Bold Coast Charter Company out of Cutler and Norton Tours out of Jonesport. If you call to make a reservation, be aware that a maximum of 15 passengers are allowed on the island. The other passengers get to see the puffins at arms-length from the boat but the blind experience simply can’t be beat.

Back aboard the Barbara Frost, we circled around the island, getting great looks at many Harbor Seals and one large Gray Seal with its horse-like head.

One of the many attractions of the Cobscook Bay region is the large amount of land with public access. Around the Bay, there are several state parks, Moosehorn National Wildlife Refuge (a unit in Edmunds and another in Baring), and several state wildlife management areas. The Quoddy Regional Land Trust and the Maine Coast Heritage Trust have preserved a number of properties and maintain trails for public access.

The Baring unit of Moosehorn NWR boasts the most easily observed Bald Eagle nest in the state. The nesting platform is only 300 yards from the road that runs through the middle of the refuge.

At Moosehorn, we walked along an abandoned railroad track just north of Route 1 through an extensive marsh. Swamp Sparrows were abundant. A Wilson’s Snipe called unseen from the marsh vegetation. We saw a couple of turtles laying eggs in the sand along the old railroad track. Unfortunately, predators had discovered a number of nests and eaten the eggs.

The Boot Cove Preserve in Lubec is a fairly easy hike through spruce-fir forest to a rocky headland. A bog with a short boardwalk along the way provides different habitat. We had great looks at Yellow-bellied Flycatchers, Nashville Warblers, both kinglets and tons of Magnolia Warblers and Black-throated Green Warblers. Sometimes, Spruce Grouse can be seen right along the trail here but we were not so fortunate. A few Blackpoll Warblers were in the stunted red spruce along the exposed headland.

West Quoddy Head State Park produced spectacular views of the rocky coast as well as Boreal Chickadees, Yellow-bellied Flycatchers, Alder Flycatchers, Yellow-rumped Warblers, Hermit Thrushes and Dark-eyed Juncos.

[Originally published on July 27, 2007]

2007-07-30T14:52:00.000-04:00

Maine Bird Tour - II

This column is the second in a series of three giving the highlights of a week-long birding tour I led for a group of Maryland birders in June.

On our third day, we left Sanford and headed toward Booth Bay Harbor. We stopped along the way at Maine Audubon in Falmouth where a Willow Flycatcher had been reported. We were able to hear the Willow Flycatcher but it bashfully never gave us a good look.

We made a quick side trip to the Wild Bird Center in Yarmouth to look for the Carolina Wren that had been sighted there. The wren scolded us from the dense shrubbery but like the Willow Flycatcher never gave us a chance to see it.

Booth Bay Harbor was our next stop where we had reservations on a whale-watching cruise. Our goal, of course, was to see some pelagic birds. We had good success in that regard on a wonderfully calm day. We saw at least 30 Greater Shearwaters, ten Sooty Shearwaters, one Northern Fulmar and the occasional Wilson’s Storm-Petrel whizzing by the boat. Northern Gannets, mostly young birds, were abundant. The six finback whales and a Minke whale we saw weren’t too bad, either!

Our last stop of the day was the Salt Bay Heritage Farm in Damariscotta. This delightful area has acres and acres of tall grass, criss-crossed by a number of walking paths. The fields were alive with Bobolinks. A pond with cattails ringing it sits in the middle of the property. A small observation deck permits close observation of the marsh/pond birds. We had Virginia Rails and Soras both calling to us as well as Marsh Wrens. A delightful way to end a day of birding.

After spending the night in Waterville, we left early in the morning for the Sidney Bog along the Middle Road in Sidney. We birded from the road rather than going onto the bog. We had the species one expects in the moat-like habitat ringing a bog: Nashville Warbler, Canada Warbler and Northern Waterthrush. On the bog, we could hear Hermit Thrush, Common Yellowthroat, Palm Warbler, White-throated Sparrow, Song Sparrow, Eastern Towhee and American Goldfinch.

Our next stop was the southwest portion of Messalonskee Lake in Belgrade. Scanning over the marsh from a small parking lot on Depot Street near Hammond’s Lumber, Al Haury found our target bird, Sandhill Crane, in less than a minute. Up to four cranes have been seen at this site.

A visit to the boat landing just a bit south on Route 27 rewarded us with great looks at Black Terns. This area hosts the largest of only a few colonies of this striking bird in the state. Other birds included Pied-billed Grebe, Wood Duck, Ring-necked Duck and Swamp Sparrow.

Highlights of a walk through the Perkins Arboretum at Colby College were a Barred Owl and a Red-shouldered Hawk.

A visit to the Pine Tree State Arboretum is always ornithologically rewarding. Eastern Bluebirds and Eastern Meadowlarks were our highlights during a late afternoon visit.

We rose quite early the next morning and drove to Long Falls Dam Road along the east side of Flagstaff Lake. This road provides easy access to boreal forest habitat. Intermittent rain throughout the morning reduced the frequency of bird song but we nevertheless managed a nice list. Swainson’s Thrushes were abundant along with Alder Flycatchers, Black-throated Green Warblers, Magnolia Warblers and Dark-eyed Juncos. We had nice looks at Black-throated Blue Warblers and heard a distant Yellow-bellied Flycatcher in one of the bogs along the road. Common Ravens flew overhead, uttering an amazing variety of vocalizations. Despite a fine cone crop, no crossbills were nesting in the area this year. No luck with Black-backed Woodpeckers, Boreal Chickadees or Gray Jays this time.

The rain held off long enough for a picnic lunch and we began our trek eastward toward Washington County. We stopped on the way at the Orono Boardwalk (http://www.oronobogwalk.org/), in search of two local specialties, Palm Warbler and Lincoln’s Sparrow. If you haven’t birded this wonderful site, you should make an effort to do so. The mile-long boardwalk is wheel-chair accessible. The boardwalk takes you through forested wetlands and then completes a circuit through a portion of the Orono Bog. We had no problem getting great looks at our two target birds from the boardwalk. Other birds there were Common Ravens, Common Yellowthroats, Song Sparrows and Purple Finches.

Just as we reached our van, the skies opened up. We drove through the rain to the Lubec area in downeast Maine where we spent the next three days.

2007-07-30T14:03:00.000-04:00

Maine Bird Tour - I

From June 16 to June 23, 2007, I led an eight-day whirlwind birding tour of Maine for six members of the Maryland Ornithological Society. Three of the group (Al Haury, Dottie Mumford and Bobbi Reichwein) were on the similar tour I led in 2003. Linda Baker, Mary Gruver-Byers and Brent Byers were new additions. Brent took the marvelous photographs that are inserted into the text. I’ll devote three columns to the highlights of the trip, sharing information on some of my favorite birding spots in the state.

After picking up the group at the Portland airport around noon on June 16, we drove to Capisic Pond for a picnic lunch. Both Orchard Orioles and Baltimore Orioles serenaded us as we ate. Other birds there were Warbling Vireos, Yellow Warblers, American Redstarts, a Green Heron and tons of Red-winged Blackbirds and Common Grackles. An Indigo Bunting sang from the top of a tree.

With our appetites sated, we headed for Evergreen Cemetery. This site is best during the spring migration but has much to offer at other seasons. We had good warbler diversity: Black-throated Green Warblers, Chestnut-sided Warblers and Common Yellowthroats being particularly common. A Rose-breasted Grosbeak first sang for us and then posed in full view. A Fish Crow gave its hoarse uh-uh call, making a nice addition to our trip list.

Next we headed to Scarborough Marsh. A quick stop at Dunstan’s Landing produced Glossy Ibis, Great Egret, Snowy Egret and Mallards. A Willet called its pill-will-willet cry, flashing the white patches on its wings as it flew across the marsh.

We made the short drive to Eastern Road in search of sharp-tailed sparrows. Scarborough Marsh is the perfect spot for these salt marsh sparrows because both the northern Nelson’s Sharp-tailed Sparrows and southern Saltmarsh Sharp-tailed Sparrows nest here. Occasionally, hybrids are seen.

On a calm June morning, males of both species will sing from the top of salt marsh grasses. However, we were at Eastern Road in the afternoon of a windy day. The sparrows could be heard singing but were reluctant to show themselves for more than a fleeting glimpse.

Our last stop of the day was Pine Point. At least 30 Bonaparte’s Gulls were present. The expected Common Terns were joined by a couple of Arctic Terns. The terns were flying close enough to allow us to see the uniformly gray upper wings of the Arctic Terns and distinctive black wedge near the tip of the wings of the Common Terns. A couple of Least Terns were present as well, distinguished by their small size, yellow bill and white forehead. As we were getting ready to call it a day, I saw a ghostly white tern fly by with a very long tail – a Roseate Tern!

After a nice meal at a Scarborough seafood restaurant, we drove to Sanford for the night. Our first stop in the morning was the Kennebunk Plains, the largest remnant of grassland in the state. Despite our fairly early start, we were not early enough for one of our target species, the Grasshopper Sparrow that breed in small numbers here. We did however have excellent views of the other specialties of the area. Upland Sandpipers gave their eerie whistles. Vesper Sparrows were in full voice and easy to see. Prairie Warblers sang from the short trees ringing the plains. Savannah Sparrows were abundant and a few Eastern Meadowlarks, a species of concern, were singing as well.

A female Northern Harrier was hunting over the grasslands along Maguire Road. At the power line cut, Eastern Towhees and a Yellow-breasted Chat were vocalizing.

The next stop was Laudholm Farm, a beautiful site with varied habitats. A Northern Mockingbird greeted us in the parking lot. The fields were full of Bobolinks. A walk through some of the woodlands produced a Red-eyed Vireo, one of whose songs was an excellent mimic of a Great Crested Flycatcher. A House Wren sang vigorously from scrubby vegetation.

A walk along the beach produced a number of Northern Gannets, some flying quite close to shore. Least Terns loafed on the beach. A highlight of the beach walk was a pair of Sanderlings in their reddish breeding plumage, quite a contrast to the pale winter plumage we normally see here.

Stops at Biddeford Pool and Eastern Point Sanctuary did not yield any surprises. We ended the day with a walk through the Saco Heath. The boardwalk provides easy access to this charming bog. Highlights were a Canada Warbler, singing Hermit Thrushes and a Blue-headed Vireo in the surrounding woods. Other people on the trail saw a moose but we had to be content with seeing only the tracks.

2007-06-13T15:43:00.000-04:00

Yellow-bellied Sapsuckers

Today's column is about a jazz drummer with a sweet tooth. No, we're not talking about Gene Krupa. The drummer is one of our more unusual woodpeckers, the Yellow-bellied Sapsucker.

The sapsucker is named for its habit of creating shallow holes, called sap wells, in the bark of trees. The sap that oozes into the wells provides food for the sapsuckers. The sap is a fluid carried in phloem cells of the tree, just beneath the bark. This fluid is rich in organic nutrients, particularly the sucrose (table sugar). These compounds are created in the leaves of the tree by the process of photosynthesis and then carried through the phloem to all parts of the tree. The phloem is essentially a circulatory system for the plant, carrying sugar to parts of the tree that cannot photosynthesize and hence make their own food. In the summer, 25% of the phloem sap is sugar. That's a sweet treat!

The sapsucker is a bit like a vampire, exposing the phloem cells and drinking the sucrose that oozes out. Unlike most woodpeckers, a sapsucker has a tongue that is brush-tipped, just the ticket for lapping up sap.

The sap wells in the phloem are usually rectangular in shape. I expect you have seen these sap wells before, arranged in neat rows parallel to the ground. A sapsucker tends the sap wells daily, making sure they to ooze sugar by enlarging the area of the well.

In the early spring before the trees have started to photosynthesize, the sapsuckers make holes in a different kind of circulatory system of the plants, the xylem. The main role of the xylem is to transport water from the roots to the aboveground parts of the tree but does contain a little sugar. The sugar in the xylem gets the sapsuckers through the latter part of the spring until the trees start to photosynthesize. The xylem wells are circular in shape and are not enlarged through time.

Over 1,000 species of trees may be used by sapsuckers across their geographic range. In Maine, sapsuckers are usually found in early-growth forests rather than mature, climax forests. Quaking Aspen, Paper Birch and Red Maple are commonly used for the creation of sap wells.

Sapsuckers will use apple trees for the creation of sap wells, causing orchard growers concern about the health of their trees. However, sapsuckers do not generally cause serious direct harm to trees, although the wells may encourage the arrival of insects that are harmful.

The dependence of sapsuckers on the phloem and xylem of birds requires sapsuckers to be migratory. Their breeding range spans the lower half of Canada, New England, Michigan, Wisconsin, Minnesota and North Dakota. The xylem and phloem of trees in these regions are frozen solid during the winter. So, the Yellow-bellied Sapsuckers withdraw to the southeastern and Gulf states into Central America for the winter. We see our first sapsuckers each spring about the middle of April.

Despite the efforts of a sapsucker to ward off other birds from its wells, many birds do take advantage of the sugar in the sap wells or the insects attracted to the sugar. Ruby-throated Hummingbirds seem to have a particularly close relationship. A female hummingbird often builds her nest close to sap wells and follows sapsuckers during the days, as they work their “trap lines”. Some ornithologists have noted that the migration of Ruby-throated Hummingbirds is closely linked to the migration of sapsuckers.

Sapsuckers do supplement their diet with insects. Foraging for insects is particularly important when parents are feeding nestlings. The young sapsuckers need protein to grow. A sugar diet alone is not sufficient for their proper development. Even so, adult sapsuckers have been seen to capture an insect and then dip it into a sap well before feeding the insect to a chick.

Most woodpeckers drum on resonating surfaces as a means of communication. Sapsuckers have an unusual, syncopated style to their drumming. A typical drum usually starts with several rapid strikes, often increasing in frequency, as an introductory roll. Then, after a brief pause, the sapsucker will strike in a slower, less regular cadence.

Like a jazz musician, sapsuckers improvise. No two drums are alike, even from the same bird.

The sapsuckers are particular about the type of tree they use for their drumming, using the trees that produce the loudest noises of the trees available. The trees chosen also yield the lowest sound frequencies. Lower-pitched sounds carry better in a closed forest habitat than higher-pitched sounds.

Most of the sapsucker drumming you hear comes from males although females also drum. Female drums are briefer and softer than the male drums.

[Originally published on June 2, 2007]

2007-06-13T15:39:00.000-04:00

Maine Butterfly Survey

Rather than writing on birds in today’s column, I’ll devote this space to another group of winged creatures, the butterflies. In particular, I want to announce the start of a five-year project to produce an atlas of the butterflies of Maine. The project is called the Maine Butterfly Survey (MBS). See the website at http://mbs.umf.maine.edu/. The MBS will rely heavily on volunteers throughout the state.

Despite the fact that butterflies are conspicuous in our gardens and fields, our knowledge of the distribution of butterflies throughout the state is fragmentary. In preparation for this atlas project, Phillip deMaynadier, a wildlife biologist at Maine Inland Fisheries and Wildlife, and Reggie Webster, a Canadian expert on the taxonomy of butterflies, searched the literature, museums and private collections for records of Maine butterflies. They found nearly 9,000 records, providing a baseline for the atlas project.

Their report, available in pdf format at the MBS website, provides township-level maps for the 114 species of butterflies in the state as well as detailed information on rare species in the state. The map of the distribution of the Monarch butterfly, an easily identified species, shows how much of the state needs to be sampled.

The Maine Butterfly Survey (MBS) follows on the heels of other butterfly atlas projects in New England and maritime Canada. Connecticut, Massachusetts and New Brunswick have recently completed atlases and Vermont is in its final year of such a survey. The coordinators of the MBS are Phillip and Reggie as well as Ron Butler of the University of Maine-Farmington and me.

Butterflies are a worthy subject for study because they contribute a colorful and conspicuous component to our state’s biological diversity. Butterflies play an important role in terrestrial and wetland ecosystems by serving both as pollinators of many wildflowers and prey (both caterpillars and adults) to larger species ranging from dragonflies to birds. Butterflies are also widely recognized for their value as ecological indicators of ecosystem stress due to such factors as climate change, pollution, and habitat loss. Without thorough baseline knowledge of the distribution and relative abundance of butterflies, it is impossible to gauge the magnitude and direction of population changes in the future to a variety of environmental variables.

The MBS will use the townships as the sampling unit. There are 711 townships in the state of Maine, most of which are roughly the same size. To document the presence of a species in a township, a voucher must be submitted. The voucher can be a specimen that is collected with a net and then submitted as a preserved specimen to the MBS for confirmation of the species.

Although there is no evidence that collecting has every led to the demise of a butterfly population, some people are reluctant to kill a butterfly in the name of science. Two other types of vouchers are acceptable for the MBS that do not depend on the collection of butterflies. Close-up digital photographs or print photographs are acceptable as vouchers. Also, road-killed specimens collected from road shoulders are acceptable vouchers as well. The number of butterflies killed by automobiles is appallingly high.

Voucher specimens are needed for any butterfly atlas so that scientists can independently verify the identifications. Sight records may be wrong and cannot be independently verified after the fact. The taxonomy of butterflies is unsettled for some species. Future taxonomists may find great value in the vouchers provided by the MBS.

I hope that you will consider becoming a volunteer for the MBS. You can contribute as few or as many vouchers as your time allows. Sampling areas are not assigned so you can sample anywhere throughout the state.

We ask that every prospective volunteer attend one of our workshops to learn the details of voucher preparation, collecting techniques and preparation of the data forms that must accompany your vouchers. Every workshop participant (eighteen years of age or older) will be given a collecting net, a specimen jar and glassine envelopes for storage of your vouchers.

The next workshop will be held on Saturday, July 14 at the Delta Institute of Natural History in Bowdoin from 9:30 AM until 3:30 PM. You’ll hear a lecture on butterfly biology and identification from me as well as instructions on data collection and butterfly netting from Ron and Phillip. If the weather is fine, we will spend part of the afternoon in the field. Please contact me soon via email to reserve a spot at the workshop; the limit is 30 people. I hope to see you in Bowdoin.

[Originally published on May 19, 2007)

2007-06-13T15:36:00.000-04:00

Comfort Behavior in Birds

As spring migration picks up the pace, all of us are excited about the return of Maine’s migratory breeding birds. Particularly during migration, birders eagerly try to see as many species as possible in a morning. It’s great fun to find that wayward Kentucky Warbler or Blue Grosbeak. However, I suggest that a closer, leisurely look at even the most common birds can be rewarding.

Like other animals, birds need to keep their skin clean and healthy. Feather maintenance is a priority as well. Most of these body-care behaviors are said to be stereotyped; that is, the birds do these same behaviors in the same way all of the time.

One of the most widely recognized stereotyped behaviors birds use to keep clean is bathing. A bird typically takes a bath by first immersing and then suddenly raising the head and then rapidly beating the wings. This bathing behavior is inborn. Young Northern Goshawks on the bare ground are induced to try to bathe when they see a brood-mate splashing in water.

In arid environments, birds take dust baths rather than water baths. It is thought that the dust removes some of the oils from the bird’s skin, which would otherwise cause matting of the feathers.

Usually, birds engage in preening after taking a bath. Preening involves the application of waxy oils to the feathers to preserve feather moisture and flexibility, waterproof the feathers and clean the feathers. The waxy oils are produced by the preen gland or uropygial gland, located on the rump at the base of the tail.

To preen, a bird rubs its bill against its preen gland to pick up some secretions from the preen gland and then uses its bill to apply the waxy oils to all the feathers of its body.

The preen glands of some birds also produce secretions that protect the feathers from feather-digesting bacteria and fungi. Other secretions may deter feather lice. In a group of birds called the hoopoes, the preen gland produces a foul-smelling substance that deters mammal predators. Hoopoes are the skunks of the bird world!

Birds spend a considerable amount of time preening. Many birds will preen their feathers once an hour. While preening, the wing and tail feathers are drawn through the bill to restore their shape. Feather parasites may be removed by preening as well.

Herons and egrets produce a peculiar type of feather called powder down. The powder down feathers are never molted but rather grow continuously. The claw of the middle toe of each foot has a comb-like undersurface that is used to crush the tips of the powder down feathers. The talcum-like powder down is spread over the feathers with the comb-claw. The powder down apparently has the same function as oil from the preen gland. The preen glands of herons are vestigial (like a human appendix) and therefore herons do not oil their feathers.

A less known form of feather and skin maintenance in songbirds is called anting in which a bird treats its feathers with ants or some other substitute material. Many ants give off pungent chemicals when they are disturbed. These chemicals serve to kill feather lice and other skin and feather parasites.

Some birds that engage in anting behavior do so passively. For instance, American Crows will spread its wings and sit down on an ant colony. The angry ants crawl through the crow’s feathers, reducing the number of parasites.

In active anting, a birds picks up one or more ants in its bill and then actively jabs them among its feathers. The bird usually ants more vigorously on the underside of its body, particularly under the wings and tail. Sometimes, an anting bird eats the ants after anting; at other times, the ants are released. Birds that practice active anting behavior include the orioles, jays and starlings.

Some songbirds don’t rely on ants for anting. Beetles, bugs, wasps, raw onion, vinegar, cigarette butts, walnut juice, lime fruit, orange peeling and mothballs may be picked up for use in anting.

Anting in Common Grackles has been observed a number of times with ants and substitute materials, including mothballs. Group anting by grackles has been described in Ohio. A woman had put out a large number of mothballs in her flower gardens to keep rabbits out. Grackles discovered the mothballs and began using them to ant. Up to two dozen grackles were seen anting at once!

Anting has been reported widely in the songbirds. Over 250 species from over 40 families have been reported to ant.

[This column originally published on May 5, 2007]

2007-06-13T15:34:00.000-04:00

Threats to Birds and Bats by Wind Turbines

In the last column, I reviewed some of the talks I heard at the recent Wilson Ornithological Society meeting in Massachusetts. I’ll discuss one last talk that has particular relevance to Earth Day.

Everyone is aware that carbon dioxide levels have been steadily increasing for the past 150 years. Most of this increase is due to industrialized nations, burning fossil fuels in our automobiles and coal to generate heat and electricity.

Carbon dioxide acts as a so-called greenhouse gas, trapping heat that is radiated into the atmosphere from the earth’s surface. The recent report “Climate Change 2007” by the International Protocol on Climate Change (http://www.ipcc.ch/) and the release of the movie “An Inconvenient Truth” featuring Al Gore have won over many skeptics who formerly doubted that significant global warming is occurring.

Environmentalists are ardently seeking greener forms of generating electricity that release little or no carbon dioxide. Wind power, a headline topic over the past year in Maine, offers the promise of a clean, renewable resource.

As with any technology, reasonable people can disagree about the relative costs and benefits. Opponents of wind power cite the disruption of scenic views and the noise that some turbines make as they turn in the wind. In most areas, the wind does not blow constantly and consequently there are times when wind will be too weak to generate electricity. Hence, a wind farm will not allow less efficient generating plants to be removed from the electrical grid. Those plants will be needed to generate power when the wind is not strong enough. Wind farms in remote areas require significant lengths of roads to be built, fragmenting the landscape.

The bird and bat mortality at wind turbines is an effect that makes many question the environmental costs of wind farms. Like real estate, location of a wind farm is a critical factor in determining the number of birds and bats that are killed. Some birds may be killed by direct contact with the rotating turbines. Other birds may be disoriented at night by the lights required on all towers taller than 200 feet. The birds may fly into a tower or guy wire with lethal results.

Quantifying the number of birds and bats killed is challenging, particularly in forested landscapes. Some birds killed by turbines may fall and remain in the forest canopy. Scavengers like foxes, coyotes and burying beetles may remove killed birds before they can be found by researchers.

Wind farm proponents admit that some bird and bat mortality is inevitable. However, they argue that the reduction in carbon dioxide emissions by using the wind to generate power improves the planet for all organisms. Deciding whether it is better to approve or deny a wind farm proposal on these grounds is a question for an environmental economist. There are no easy answers.

At the Wilson Ornithological Society meeting, I looked forward to hearing Rhonda Millikin speak on her work on the response of nocturnal migrating birds to wind turbines. She has pioneered a radar-acoustic system to determine how birds and bats respond to spinning turbine blades.

She applied her technology at six wind farms in Alberta in agricultural landscapes and one wind farm in Ontario in a forested landscape. She tested the hypothesis that nocturnal bird and bat migrants could avoid the turbines.

Millikin measured the avoidance of turbines by looking for changes in flight behavior as birds and bats approached the blades. She found that birds were able to detect the turbines from a distance of at least 500 yards away by showing that the birds slowed their flight speed and increased their calling rate. They also flew a bit higher, rarely dipping below the height of a wind turbine. Millikin argued that birds may learn to avoid turbines.

Bats are a different story. As they approach a turbine, they climb to an altitude equal to the spinning blades and vary their flight direction. They respond quite late to the towers, often not trying to fly to safety until they are within 50 m of the turbine. Because of their erratic flight and slow responses, bats have a difficult time traversing a line of turbines. Millikin claimed that a bat is about five times as likely as a bird to be killed when flying in the vicinity of a turbine.

Millikin ended her talk by noting particular habitats where migrating birds are reluctant to change their course. These habitats are ridges, riparian habitats and ravines or gulches with steep sides. Migrating birds have a strong attraction for these areas as they migrate and hence are less likely to avoid turbines. Wind turbines in these types of habitats pose higher risks for birds and bats.

[First published on April 21, 2007]

2007-06-13T09:14:00.000-04:00

Highlights from the 2007 Wilson Ornithological Society meeting

I recently attended the annual meeting of the Wilson Ornithological Society, held in the Boston area this year. In today’s column, I’ll describe some of the new research presented at the meeting.

The meeting began with a talk on Alexander Wilson, the father of American ornithology. The Wilson Ornithological Society is named in his honor. Wilson was born in Scotland in 1766. In his early adulthood, he was a weaver and peddler, a poet and a labor union organizer. He immigrated to Philadelphia in 1794, fearing he would be jailed in Scotland.

In In Delaware, he taught school and began drawing to alleviate his frequent depressions. He had the good fortune to meet William Bartram, the most famous and influential naturalist in North America.

In 1803, Wilson decided to describe and paint all of the birds of North America. Over seven years, he traveled over 10,000 miles studying birds. The first volume of the “American Ornithology” was published in 1808 with a second volume in 1810. Six volumes were published in 1813, the year that Wilson died. One last volume was published posthumously in 1814. All told, 264 species were covered in the nine volumes. Wilson’s volumes preceded John James Audubon’s by a decade, establishing Wilson as the father of American ornithology.

Wilson and Audubon had an amicable meeting in Louisville where Audubon was living at the time. Wilson asked Audubon to buy a subscription to “American Ornithology” and must have been embarrassed when Audubon showed him some of his own paintings of birds!

One of the highlights of this year’s meeting was a chance to see some of Wilson’s original paintings and the specimens on which they were based (including a Bald Eagle) at the Museum of Comparative Zoology at Harvard. Wilson’s paintings are accurate representations of the birds he saw but are not the artistic masterpieces that Audubon produced. It is not unfair to state that Wilson was an illustrator and Audubon was an artist.

Bob Curry and his students at Villanova University gave a talk on the hybrid zone between Black-capped Chickadees and Carolina Chickadees in southeastern Pennsylvania. They used DNA markers to determine if hybridization was occurred. Three sites were sampled: one southern site at Great Marsh where only Carolina Chickadees occur, an intermediate site in Nolde Forest where most individuals are hybrids and a northern site at Hawk Mountain with mostly Black-capped Chickadees but with some evidence of hybridization occurring.

Comparison to earlier studies indicates that the hybrid zone has shifted north about 15 miles over the past 15 years. The hybrid zone, now about 30 miles wide, seems to have broadened in recent years as well.

David Lahti from the University of Massachusetts gave a talk on the advantages of blue-green bird eggs. Most bird eggs are cryptically colored. Why would birds like American Robins lay blue-green eggs that should be easier to find for a predator than speckled or dark eggs?

Lahti suggests that the blue-green pigment in the eggs serves as a parasol for the developing eggs. In other words, the pigment may protect the developing embryo from the solar radiation in forest environments. He was able to show in the laboratory that the pigment keeps light rays from entering the egg, preventing the eggs from heating up.

Jim Chace from Salve Regina University in Rhode Island described research he and his students have been doing in Vermont on breeding Canada Warblers. Various sources of information, including the Breeding Bird Survey, indicate this species has been declining for the past 30 years. Yet, little is known of the characteristics of the habitat that males use when establishing territories. By comparing the vegetation within Canada Warbler territories with randomly chosen habitats, Chace and his students showed that males preferred habitat with denser shrubs and saplings and a greater ground cover of moss than randomly chosen sites within the large study area. This knowledge provides environmental managers with ways to improve habitat for Canada Warbler nesting.

Steven Reinert of the Block Island Banding Station in Rhode Island presented a talk on the bias of mist-net captures in monitoring landbird fall migration. Over the past 37 years, the Audubon Society of Rhode Island has hosted an annual Block Island Birding Weekend. Expert birders lead small groups of birders around this island, identifying and counting all birds during the middle of the fall migration season. Reinert used thee counts to compare to the relative abundances of landbirds he and his associates capture in their mist-nets over the same weekend. Over the 37-year period, 152 species were identified by sight and only 91 captured in nets. Most landbirds are absent or under-represented in mist-net captures.

[Originally published on April 7, 2007]