Bicknell’s Thrush (Catharus bicknelli) distribution and population estimates on breeding and wintering areas

The enigmatic Bicknell’s Thrush, with its swirling flute-like song and speckled breast, is one of the most range-restricted songbirds in North America. It breeds in cool, moist evergreen forests on high mountains of the northeastern U.S. and coastal lowlands of southeastern Canada. Over the next several hundred years, climate change is expected to cut in half the extent of Bicknell’s Thrush breeding habitat in the Northeast. During the winter months, this species retreats to wet broadleaf forests in the Greater Antilles, where it faces ongoing habitat loss in its wintering range on the islands of Hispaniola, Cuba, Jamaica, and Puerto Rico. In light of its small geographic range and threats to its breeding and winter habitats, Bicknell’s Thrush is currently a candidate for listing under the U.S. Endangered Species Act. The species is already listed as Threatened under Canada’s Species at Risk Act.

Newest research by the Vermont Center for Ecostudies (VCE) has revealed that Bicknell’s Thrush likely have one of the smallest population sizes - about 71,000 adult birds - of any migratory songbird within the contiguous U.S. and Canada (Hill and Lloyd 2017). The VCE study also indicates that 85% of the U.S. Bicknell’s Thrush population occurs on conserved lands, including state and national forests and private lands with conservation easements. In fact, more than half of the U.S. Bicknell’s Thrush population likely occurs on just three blocks of public land: White Mountain National Forest in New Hampshire and Maine, Baxter State Park in Maine, and the High Peaks Wilderness Area of the Adirondack Park in New York. White Mountain National Forest in New Hampshire, alone, likely harbors nearly one-third - about 22,000 adult birds - of the U.S. Bicknell’s Thrush population and perhaps 18% of the global (U.S. and Canada) population.

The International Bicknell’s Thrush Conservation Group (IBTCG) recently completed an updated plan to protect Bicknell’s Thrush across its entire range, from the Caribbean to Canada, that addresses the primary threats facing Bicknell’s Thrush and the actions that may help mitigate them. The IBTCG is an alliance of scientists, natural-resource managers, and government officials committed to advancing the study and conservation of Bicknell’s Thrush through sound science and international cooperation,

For those of you new to Data Basin and our dataset, we've created a short video on our YouTube channel that explains how to use this data.

For those of you familiar with Data Basin, the variable displayed on the map for each cell is Nhat - the mean expected abundance for Bicknell's Thrush in 2016 given the elevation, latitude and forest cover at the site. See our published paper below for more detailed information.