Direct tracking methods in combination with remote sensing data allow examination of habitat use by birds during migration. Species that roost communally during migration, such as some swallows, form large aggregations that can attract both avian and terrestrial predators. However, the extent to which they might use patchy habitats that could reduce predation risk during migration is unknown. We tested the hypothesis that Purple Martins (Progne subis) use forest islands (patches of suitable forest habitat surrounded by unsuitable habitat) as roost sites during migration between breeding sites in North America and overwintering sites in South America. We used high‐precision (< 10 m), archival GPS units deployed and retrieved during the 2015 and 2016 breeding seasons, respectively, at 12 colonies located across eastern North America. We found that Purple Martins roosted in forest islands more often than expected based on availability during both spring and fall migration. Despite an apparent association with urban habitats by Purple Martins based on observational and radar data in North America during the fall, the roost locations we identified during spring and fall migration were not more closely associated with urban areas than random locations. The use of forest islands during both spring and fall migration suggest that Purple Martins may use these habitats to reduce predation risk during migration. Our results suggest that some species of birds may use similar habitats as stopover sites during migration and that patches of forest habitat may be important conservation targets for Purple Martins and other species. Identifying habitat use during migration represents an important advance in support of full annual‐cycle conservation of Purple Martins and other migratory species with declining populations.

中文翻译：

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精确的直接跟踪和遥感揭示了紫色马丁斯在迁徙期间将森林岛屿用作栖息地的情况

直接跟踪方法与遥感数据相结合，可以检查鸟类在迁徙期间对栖息地的使用情况。在迁徙过程中会集体栖息的物种（例如一些燕子）会形成大型聚集体，从而吸引鸟类和陆地掠食者。但是，他们在多大程度上使用斑驳的栖息地以减少迁徙期间的捕食风险尚不清楚。我们检验了紫色马丁斯（Progne subis）在北美繁殖地和南美越冬地之间迁徙期间，将森林岛（适合的森林栖息地斑块包围不适当的栖息地）用作栖息地。我们分别在2015年和2016年繁殖季节期间使用了高精度（<10 m）档案GPS装置，该装置已在北美东部的12个殖民地部署和回收。根据春季和秋季迁徙期间的可用性，我们发现紫马丁栖息在森林岛上的次数比预期的多。尽管紫色马丁斯根据秋季在北美的观测和雷达数据与紫罗兰色的城市栖息地存在明显联系，但我们在春季和秋季迁徙期间确定的栖息地与城市地区的联系并不比随机地点紧密。在春季和秋季迁徙期间都使用森林岛屿，这表明紫马丁可以利用这些栖息地来减少迁徙期间的捕食风险。我们的研究结果表明，某些鸟类可能在迁徙期间将相似的栖息地用作中转站，而森林栖息地的斑块可能是紫马丁和其他物种的重要保护目标。识别迁徙期间的栖息地使用，是支持紫色马丁斯和其他人口减少的迁徙物种的完整年度保护的重要进展。我们的研究结果表明，某些鸟类可能在迁徙期间将相似的栖息地用作中转站，而森林栖息地的斑块可能是紫马丁和其他物种的重要保护目标。识别迁徙期间的栖息地使用，是支持紫色马丁斯和其他人口减少的迁徙物种的完整年度保护的重要进展。我们的研究结果表明，某些鸟类可能在迁徙期间将相似的栖息地用作中转站，而森林栖息地的斑块可能是紫马丁和其他物种的重要保护目标。识别迁徙期间的栖息地使用，是支持紫色马丁斯和其他人口减少的迁徙物种的完整年度保护的重要进展。