Spatial segregation between Gray-cheeked Thrush and an introduced nest predator in a managed forest landscape

Introduced species are known for inducing changes in ecosystems and their impacts on endemic island species. North American red squirrels (Tamiasciurus hudsonicus) were introduced to Newfoundland, Canada, during the 1960s have been hypothesized as a cause of precipitous decline Newfoundland Gray-cheeked Thrush (Catharus minimus minimus). To test prediction that led range contraction by thrushes, we completed 1960 point count surveys squirrel thrush over two years (2016 2017) western Newfoundland. Thrushes strongly segregated elevation, with thrushes now being commonly detected at only high most frequently low both rare inversely likely be present intermediate elevations. We evaluated local (5.5 ha) landscape (490.8 scale habitat affiliations using landcover data from provincial forest resource inventory assess potential synergistic invasion management. associated regenerating (10–30 post-harvest) clear-cuts, conifer forest, tall scrub scale, but avoided scrub, stands, second growth scale. Regenerating clear-cuts modified strip cuts selected Breeding Bird Survey show abundant lower elevations prior expansion across so our finding strong elevational segregation adds growing body evidence suggesting introduction played an important role sudden this insular songbird subspecies. Management should include efforts prevent spread upslope nearshore islands while more study is done other hypotheses regarding decline, well relevant aspects ecology little-studied thrush.