Appalachian Laboratory, University of Maryland Center for Environmental Science, Frostburg, MD 21532.
Powdermill Nature Reserve, Carnegie Museum of Natural History, Rector, PA 15677.
Proc Natl Acad Sci U S A. 2024 Aug 20;121(34):e2322063121. doi: 10.1073/pnas.2322063121. Epub 2024 Aug 13.
Global migrations of diverse animal species often converge along the same routes, bringing together seasonal assemblages of animals that may compete, prey on each other, and share information or pathogens. These interspecific interactions, when energetic demands are high and the time to complete journeys is short, may influence survival, migratory success, stopover ecology, and migratory routes. Numerous accounts suggest that interspecific co-migrations are globally distributed in aerial, aquatic, and terrestrial systems, although the study of migration to date has rarely investigated species interactions among migrating animals. Here, we test the hypothesis that migrating animals are communities engaged in networks of ecological interactions. We leverage over half a million records of 50 bird species from five bird banding sites collected over 8 to 23 y to test for species associations using social network analyses. We find strong support for persistent species relationships across sites and between spring and fall migration. These relationships may be ecologically meaningful: They are often stronger among phylogenetically related species with similar foraging behaviors and nonbreeding ranges even after accounting for the nonsocial contributions to associations, including overlap in migration timing and habitat use. While interspecific interactions could result in costly competition or beneficial information exchange, we find that relationships are largely positive, suggesting limited competitive exclusion at the scale of a banding station during migratory stopovers. Our findings support an understanding of animal migrations that consist of networked communities rather than random assemblages of independently migrating species, encouraging future studies of the nature and consequences of co-migrant interactions.
全球不同动物物种的迁徙经常沿着相同的路线汇聚，将可能相互竞争、捕食彼此并共享信息或病原体的季节性动物组合聚集在一起。这些种间相互作用，在能量需求高且完成旅程的时间短的情况下，可能会影响生存、迁徙成功、中途停留生态和迁徙路线。有许多报道表明，种间共同迁徙在航空、水和陆地系统中是全球性分布的，尽管迄今为止的迁徙研究很少调查迁徙动物之间的物种相互作用。在这里，我们检验了一个假设，即迁徙动物是参与生态相互作用网络的群落。我们利用五个鸟类环志站在 8 到 23 年期间收集的超过 50 种鸟类的超过 50 万份记录，使用社会网络分析来测试物种关联。我们发现，在不同地点之间以及在春季和秋季迁徙之间，物种关系具有很强的持续性。这些关系可能具有生态意义：它们经常在具有相似觅食行为和非繁殖范围的亲缘关系物种之间更强，即使在考虑到与关联相关的非社会性贡献（包括迁徙时间和栖息地使用的重叠）之后也是如此。虽然种间相互作用可能导致代价高昂的竞争或有益的信息交换，但我们发现关系主要是积极的，这表明在迁徙中途停留期间，在环志站的规模上，竞争排斥的情况有限。我们的研究结果支持了一种理解动物迁徙的方式，即迁徙动物群落由网络组成，而不是独立迁徙物种的随机组合，鼓励未来对共同迁徙物种相互作用的性质和后果进行研究。
