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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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!

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]