The Bicknell’s thrush, which breeds in the Adirondacks and northern New England, is at risk from climate change, acid rain, mercury, and habitat destruction, but it is not on the federal list of endangered species.
The Center for Biological Diversity is trying to change that. In 2010, the nonprofit organization filed a scientific petition with the U.S. Fish and Wildlife Service to persuade the agency to designate the bird as endangered or threatened.
The Bicknell’s thrush breeds only in high-elevation spruce-fir forests in New York, Vermont, New Hampshire, Maine, and southeastern Canada. Because of its limited range, scientists have long assumed that its population is relatively small.
A just-released study by the Vermont Center for Ecostudies confirms that suspicion. Using data from volunteer and professional researchers, the study estimates that there are 71,300 Bicknell’s specimens in the United States. Taking into account Canada, the study says the global population is less than 120,000—“one the smallest population sizes … of regularly occurring passerine species within the contiguous United States and Canada.”
By comparison, the populations of the two related species, the veery and the gray-cheeked thrush, are approximately 11 million and 15 million, respectively.
The White Mountains of New Hampshire has the largest population of Bicknell’s thrush in the United States—some 26,400 specimens, according to the study. The Adirondack population is estimated to be 17,600, about a quarter of the U.S. total.
Mollie Matteson, a senior scientist with the Center for Biological Diversity, said the biggest immediate threat to the Bicknell’s is the destruction of its winter habitat in the Dominican Republic. In the long run, however, climate change poses a larger threat. The study predicts that more than half of the high-elevation spruce forests in the Northeast could be lost between 2100 and 2300. Acid rain also is damaging the thrush’s habitat. Mercury pollution from distant power plants is another concern.
If the Fish and Wild Service agrees that the Bicknell’s is endangered or threatened, it would then write a plan to protect the species.
The agency has until September 30 to act. If the Center for Biological Diversity disagrees with the decision, it could file a legal challenge.
In New York State, the Bicknell’s is listed as a species of special concern, a less-protective designation than either endangered or threatened.