The Song Ends Here: Climate Change

A mountainous North Country bird is threatened by climate change

Story by Ashlie Doran


As you climb the gravel path to the summit of Mount Mansfield in Vermont, the leaves' green colors darken as the sun makes its slow descent from the sky. By chance, you may hear a small brown bird singing its nasal, gyrating song on a small fir branch.

This bird, Bicknell's Thrush, can be found in overgrowths of balsam fir and red spruce forests, generally in locations that were formally disturbed at altitudes above 1,100 meters in elevation, according to The Birds of North America, "Bicknell's Thrush," by C.C. Rimmer. The breeding range of Bicknell's Thrush spans in mountainous region fragments from the northern Gulf of St. Lawrence and easternmost Nova Scotia to the southwest Catskill Mountains of New York.

Bicknell's thrush
Bicknell's Thrush populate balsam fir and red spruce forests.

Photo copyrighted of Marcel Gahbauer
Photo courtesy of

However, this small brown bird is scarcely known by ornithologists or bird watchers because of its reclusive behavior and remote habitat. It is among the rarest birds to witness and, possibly, one of the most threatened. Less than forty thousand Bicknell's Thrushes remain within its estimated breeding ground, and these meager numbers reflect a dwindling habitat. Balsam firs have a specific temperature range to survive. When the temperature rises beyond its range, the firs move up the mountain, where cooler temperatures exist. But eventually, there will be no more room left to move up to these temperatures.

A study by the United States Department of Agriculture shows the area covered by balsam fir forests may be reduced by 96 percent with the anticipated 1.6 to 6.3 percent increase in surface temperature associated with global warming. "Global warming may pose the greatest single threat to the long-term survival of this vulnerable species," says Dan Lambert, a Vermont Institute of Natural Science biologist.

Not only is the bird's summer residence dwindling, but the winter home of Bicknell's Thrush is also at risk because of foresting. The birds' winter home only consists of four Caribbean islands—Hispañola, Jamaica, Puerto Rico, and Cuba. According to the National Audubon Society, the bird's wintering grounds on these four islands have already been reduced by as much as 80 to 90 percent through clearing for agriculture and human settlement. Population in these areas is expected to double in the next ten to twenty years.

"Global warming may pose the greatest single threat to the long-term survival of this vulnerable species."

Bicknell's Thrush prefers balsam fir forests to blue spruce, white birch, or mountain ash. The birds are very picky about this, especially during their mating season. "Bicknell's Thrush is a very rare bird that practices both polyandry and polygamy, while 95 percent of the song birds in America are monogamous," says Allan Strong, an ornithologist and professor at the Vermont Institute of Natural Science. Polyandry is a term describing a female mating with several different males, while polygamy describes a male mating with several different females. The bird's promiscuity is beneficial because when there is a food shortage, the chicks are more likely to survive, since they have multiple fathers trying to feed them.

Map of breeding ground
Bicknell's Thrush winter and summer homes.

Source: The Birds of North America. "Bicknell's Thrush." C. C. Rimmer et al.

However, the balsam firs' two year cone cycle is an additional opponent to the small birds' survival. "After a cone crop, red squirrels take advantage of the increase in food and reproduce more. Then, in the spring there are no cones, so the squirrels turn to bird nests," says Strong. So every two years, Bicknell's Thrush goes through fluctuations, due to hungry squirrels. However, the birds' numbers are so few that they have trouble rebounding after a year when the squirrels have overproduced and the firs stop cone production.

Partners in Flight ranks Bicknell's Thrush as the top conservation priority among neotropical migrants in the Northeast, while the International Union for the Conservation of Nature classifies the species as "vulnerable" on its list of threatened species.

Climatologist and professor at Plattsburgh State University College, Charles Zinser, currently notices global warming and climate change implications in the North Country. According to Zinser, there was dependable snow coverage by Thanksgiving and would stay until March, approximately twenty-five years ago. Now, the snow is coming later and leaving sooner.

Both Zinser and John Moravek, a geography professor at the Plattsburgh State University College, have noticed that robins, starlings, geese, black birds, and red wings have been migrating back north to their summer regions earlier and staying longer. In Zinzer's mind, there is no question that human activities are the leading cause of the acceleration of global warming and climate change as a whole. From 1880 to 2000, carbon dioxide gas have been on the rise.

If this trend continues, Bicknell's Thrush may become extinct, putting an end to the gyrating, nasal song that can be heard in forests throughout upstate New York and Canada.


How do you feel about Global Warming in the Adirondacks?

The Itty-Gritty of Global Warming

The "Greenhouse Effect" works similarly to what happens when a car's windows are closed on a hot day while the inside heats up substantially. Carbon dioxide in the atmosphere helps control the earth's temperature. Many studies have correlated the accelerated burning of fossil fuels since the Industrial Revolution to the increased concentration of carbon dioxide in the atmosphere.

However, as President George W. Bush says, "America is addicted to oil." The United States has the highest carbon dioxide emissions in the world, according to the Oak Ridge National Research Laboratory. The Union of Concerned Scientists: Citizens and Scientists for Environmental Solutions estimates carbon emissions from all sources of fossil fuel have been burning for a maximum period from 1751 to 1996.

The reduction of carbon dioxide is essential but the United States did not sign the Kyoto Protocol to reduce this gas emission because any reduction in the oil market would have a substantial negative impact on our economy.

 

The World's Top Ten Carbon Dioxide Emitters (by 1,000 tons of Carbon)

1. United States- 1,446,777
2. Peoples Rep. of China- 917,997
3. Russian Federation- 431,090
4. Japan- 318,686
5. India- 272,212
6. Germany- 235,050
7. United Kingdom- 152,015
8. Canada- 111,723
9. South Korea- 111,370
10. Italy- 110,052

 

More Bad News for Threatened Species

Additionally, the weakening of the Endangered Species Act puts Bicknell's Thrush, and future animals, at even greater risk. However, a petition to maintain the Endangered Species Act was submitted to Congress on March 8, 2006. The proposed changes to the Endangered Species Act include transferring authority from scientists to government authorities in the Department of the Interior. There are also changes to the protection of threatened and endangered animals' habitat. Only empirical data is considered to weigh the need for protecting a certain animal. This forbids scientists from using sampling and other statistical analysis to infer the population and degree of endangerment a species is in.

Copyright © 2001 - 2006 All Points North. All Rights Reserved