Bicknell’s Thrush (Catharus bicknelli) habitat occupancy in Québec’s Laurentian Highlands

摘要

In North America, several migratory bird species inhabiting boreal and eastern forests are declining. Habitat loss is frequently cited as a limiting factor. We estimated occupancy of suitable nesting habitat by Bicknell’s Thrush (Catharus bicknelli), a forest dwelling threatened species, in the Laurentian Highlands of Québec. Forests in this region are shaped by intensive forestry activities and natural disturbances. The species was found primarily in stands of about 20 years or more, with higher occupancy in older stands on hilltops where recent forestry activities and natural perturbations have been much less prevalent. Bicknell's Thrush occupancy was significantly associated with high elevations in landscapes with relatively low amounts of precommercial thinning. Occupancy and multivariate niche approaches indicated that a large extent of potential habitat (> 80%) was unoccupied by breeding Bicknell’s Thrushes. We conclude that maintaining sufficient amounts of suitable breeding habitat in this exploited forest landscape remains important to enable the species’ recovery, but that an increase in its numbers may not materialize without further measures unrelated to availability of breeding habitat.