Department of Biology, Centre for Animal Movement Research, Lund University, Ecology Building, 22362 Lund, Sweden.
Department of Environmental Science and Bioscience, Kristianstad University, 29188 Kristianstad, Sweden.
Biol Open. 2021 Apr 15;10(4). doi: 10.1242/bio.058655. Epub 2021 Apr 27.
We investigated the migratory orientation of early and late captured dunlins, Calidris alpina, by recording their migratory activity in circular orientation cages during autumn at a staging site in southwest Alaska and performed route simulations to the wintering areas. Two races of dunlins breeding in Alaska have different wintering grounds in North America (Pacific Northwest), and East Asia. Dunlins caught early in autumn (presumably Calidris alpinapacifica) oriented towards their wintering areas (east-southeast; ESE) supporting the idea that they migrate nonstop over the Gulf of Alaska to the Pacific Northwest. We found no difference in orientation between adult and juveniles, nor between fat and lean birds or under clear and overcast skies demonstrating that age, energetic status and cloud cover did not affect the dunlins' migratory orientation. Later in autumn, we recorded orientation responses towards south-southwest suggesting arrival of the northern subspecies Calidris alpinaarcticola at our site. Route simulations revealed multiple compass mechanisms were compatible with the initial direction of early dunlins wintering in the Pacific Northwest, and for late dunlins migrating to East Asia. Future high-resolution tracking would reveal routes, stopover use including local movements and possible course shifts during migration from Alaska to wintering sites on both sides of the north Pacific Ocean.
我们通过在阿拉斯加西南部的一个中途停留地的秋季，在圆形定向笼中记录迁徙活动，研究了早期和晚期捕获的黑腹滨鹬（Calidris alpina）的迁徙方向，并进行了路线模拟以到达冬季栖息地。在阿拉斯加繁殖的黑腹滨鹬有两个亚种，它们在北美的冬季栖息地（太平洋西北部）和东亚不同。秋季早期捕获的黑腹滨鹬（推测为 Calidris alpinapacifica）定向飞往其冬季栖息地（东南偏东；ESE），这支持了它们在穿越阿拉斯加湾到太平洋西北部的过程中不停迁徙的观点。我们发现，在定向方面，成年个体和幼鸟之间、胖鸟和瘦鸟之间、晴天和阴天之间没有差异，这表明年龄、能量状态和云层覆盖不会影响黑腹滨鹬的迁徙方向。在秋季后期，我们记录到了朝向西南偏南的定向反应，表明北方亚种 Calidris alpinaarcticola 到达了我们的地点。路线模拟显示，多种罗盘机制与早期黑腹滨鹬在太平洋西北部越冬的初始方向以及晚期黑腹滨鹬迁徙到东亚的方向兼容。未来的高分辨率跟踪将揭示从阿拉斯加到北太平洋两侧越冬地的迁徙路线、中途停留地的使用情况，包括当地的运动和可能的航线改变。
