Distribution of Bicknell's thrush in New England and New York

We conducted presence-absence surveys for Bicknell's Thrush (Catharus bicknelli) in Marine, Massachusetts, New Hampshire, New York, and Vermont during the 1992-1995 breeding seasons. The species was found at 234 sites, of which 225 (96%) were dominated by varying mixtures of balsam fir (Abies balsamea) and red spruce (Picea rubens). Ninety-one percent of the occupied sites were greater than or equal to 915 m (3000 ft) in elevation. Size of occupied habitat patches was generally small; 73% of occupied areas delimited by the 915 m elevation contour were less than 1000 ha in extent. A logistic regression model using independent variables describing vegetation, Elevation, land area greater than or equal to 915 m located within 1 km of a site, and latitude successfully predicted thrush presence. There was no conclusive evidence of widespread population declines of Bicknell's Thrush in the United States; we found the species at 63 of 73 sites (86%) known to have been occupied prior to 1992. However, the restricted breeding distribution and narrow habitat requirements of Bicknell's Thrush in the United States suggest that it is vulnerable to habitat loss and degradation, and that continued efforts to document the species' status and ecology are warranted.