HABITAT USE BY THE BICKNELL'S THRUSH IN THE ESTRIE REGION, QUEBEC

Abstract

Concern has been raised that the viability of Bicknell's Thrush (Catharus bicknelli) populations is precarious due, in part, to threats to its breeding habitat. Qualitative descriptions of habitat use have suggested that the species breeds primarily in dense, high elevation forests of northeastern North America. However, there is little quantitative information on habitat use patterns, which impedes formulation of effective conservation plans. To address this knowledge gap, we characterized the habitat of 42 sites occupied by Bicknell's Thrushes and 19 unoccupied sites on two mountains in the Estrie region, Quebec. Occupied sites were dominated by balsam fir (Abies balsamea) growing at high density, whereas unoccupied sites had a larger component of hardwoods at lower density. We found significant differences in vegetation composition and habitat structure between occupied and unoccupied sites for each mountain separately, and the two combined, though the particular variables distinguishing the two site types varied between the two mountains likely because of differences in management history. Our results show that the structure of occupied habitats may differ among sites even within a single region. However, it was evident that dense balsam fir-dominated habitats were used selectively by Bicknell's Thrushes at both study sites, and that the maintenance of such habitats should be a conservation priority in the Estrie region.