Bathrick Rosalyn E, Johnson James A, Ruthrauff Daniel R, Snyder Rebekah, Stager Maria, Senner Nathan R
Organismic and Evolutionary Biology Program, University of Massachusetts Amherst, Amherst, MA, USA.
U.S. Fish & Wildlife Service, Migratory Bird Management, Anchorage, AK, USA.
Mov Ecol. 2024 Oct 14;12(1):70. doi: 10.1186/s40462-024-00509-2.
Ecological barriers can shape the movement strategies of migratory animals that navigate around or across them, creating migratory divides. Wind plays a large role in facilitating aerial migrations and can temporally or spatially change the challenge posed by an ecological barrier, with beneficial winds potentially converting a barrier into a corridor. Here, we explore the role wind plays in shaping initial southbound migration strategy among individuals breeding at two sites along an ecological barrier.
Using GPS satellite transmitters, we tracked the southbound migrations of Short-billed Dowitchers (Limnodromus griseus caurinus) from two breeding sites in Alaska to nonbreeding sites in coastal Mexico. The breeding sites were positioned in distinct regions along an ecological barrier - the Gulf of Alaska. We investigated potential differences in migratory timing, wind availability, and tailwind support en route across the Gulf of Alaska between individuals breeding at the two sites.
Route choice and arrival timing to wintering sites differed markedly between the two breeding sites: individuals departing from the more westerly site left at the same time as those from further east but crossed the Gulf of Alaska farther west and arrived along the Pacific coast of Mexico an average of 19 days earlier than their counterparts. Dowitchers from both sites departed with slight tailwinds, but once aloft over the Gulf of Alaska, birds from the more westerly site had up to twelve times more tailwind assistance than birds from the more easterly one.
The distinct migration strategies and degree of wind assistance experienced by birds at these two breeding sites demonstrates how differences in wind availability along migratory routes can form the basis for intraspecific variation in migration strategies with potential carryover effects. Future changes in wind regimes may therefore interact with changes in habitat availability to influence migration patterns and migratory bird conservation.
生态屏障能够塑造迁徙动物的移动策略，这些动物会围绕或穿越这些屏障进行导航，从而形成迁徙分界线。风在促进空中迁徙方面起着重要作用，并且可以在时间或空间上改变生态屏障带来的挑战，有利的风有可能将屏障转变为通道。在这里，我们探讨风在塑造沿着生态屏障的两个繁殖地繁殖的个体的初始南迁策略中所起的作用。
我们使用GPS卫星发射器追踪了短嘴半蹼鹬（Limnodromus griseus caurinus）从阿拉斯加的两个繁殖地到墨西哥沿海非繁殖地的南迁过程。这些繁殖地位于阿拉斯加湾这一生态屏障沿线的不同区域。我们研究了在阿拉斯加湾上空迁徙途中，两个繁殖地的个体在迁徙时间、风况以及顺风支持方面的潜在差异。
两个繁殖地的个体在越冬地的路线选择和到达时间存在显著差异：从更西边繁殖地出发的个体与更东边繁殖地的个体同时出发，但在更西边穿越阿拉斯加湾，并比来自更东边繁殖地的个体平均早19天到达墨西哥太平洋沿岸。来自两个繁殖地的半蹼鹬出发时都有轻微顺风，但一旦飞到阿拉斯加湾上空，来自更西边繁殖地的鸟类所获得的顺风助力比来自更东边繁殖地的鸟类多多达12倍。
这两个繁殖地的鸟类所经历的不同迁徙策略和风力辅助程度表明，迁徙路线上风况的差异如何能够形成种内迁徙策略变化的基础，并可能产生连锁效应。因此，未来风况的变化可能会与栖息地可利用性的变化相互作用，从而影响迁徙模式和候鸟保护。
