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

The post Spatial segregation between Gray-cheeked Thrush and an introduced nest predator in a managed forest landscape first appeared on Avian Conservation and Ecology.

引进物种因引起生态系统变化及其对特有岛屿物种的影响而闻名。北美红松鼠 ( Tamiasciurus hudsonicus ) 在 20 世纪 60 年代被引入加拿大纽芬兰，并被推测是纽芬兰灰颊鸫 ( Catharus minimus minimus )急剧下降的原因）。为了验证松鼠的影响导致画眉鸟活动范围缩小的预测，我们在纽芬兰西部两年（2016 年和 2017 年）完成了 1960 个松鼠和画眉鸟的点计数调查。画眉鸟和松鼠按海拔高度隔离，画眉鸟现在通常只在高海拔地区被发现，松鼠最常在低海拔地区被发现，而这两种物种都很罕见，而且在中等海拔地区也很可能出现。我们使用省级森林资源清单中的土地覆盖数据评估了画眉的局部（5.5 公顷）和景观（490.8 公顷）规模的栖息地从属关系，以评估松鼠入侵和森林管理对画眉的协同影响的潜力。灰颊画眉与再生（收获后 10-30 年）的砍伐、针叶林、局部尺度上存在高灌木丛，但在景观尺度上避免了高灌木丛、再生林和次生林。画眉在局部范围内选择再生皆伐和改良的条状切口。鸟类繁殖调查数据显示，在松鼠在纽芬兰扩张之前，灰颊鸫在较低海拔地区大量存在，因此我们对强烈海拔隔离的发现增加了越来越多的证据，表明松鼠的引入在鸟类迁徙过程中发挥了重要作用。这种岛屿鸣禽亚种的突然衰退和活动范围缩小。对松鼠的管理应包括努力防止向上蔓延和向近岸岛屿蔓延，同时对这一点和其他有关灰颊画眉数量下降原因的假设进行更多研究，

管理森林景观中灰颊鸫和引入的巢捕食者之间的后空间隔离首次出现在《鸟类保护与生态学》上。