Tøttrup Anders P, Thorup Kasper, Rainio Kalle, Yosef Reuven, Lehikoinen Esa, Rahbek Carsten
Center for Macroecology and Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark.
Biol Lett. 2008 Dec 23;4(6):685-8. doi: 10.1098/rsbl.2008.0290.
The onset of migration in birds is assumed to be primarily under endogenous control in long-distance migrants. Recently, climate changes appear to have been driving a rapid change in breeding area arrival. However, little is known about the climatic factors affecting migratory birds during the migration cycle, or whether recently reported phenological changes are caused by plastic behavioural responses or evolutionary change. Here, we investigate how environmental conditions in the wintering areas as well as en route towards breeding areas affect timing of migration. Using data from 1984 to 2004 covering the entire migration period every year from observatories located in the Middle East and northern Europe, we show that passage of the Sahara Desert is delayed and correlated with improved conditions in the wintering areas. By contrast, migrants travel more rapidly through Europe, and adjust their breeding area arrival time in response to improved environmental conditions en route. Previous studies have reported opposing results from a different migration route through the Mediterranean region (Italy). We argue that the simplest explanation for different phenological patterns at different latitudes and between migratory routes appears to be phenotypic responses to spatial variability in conditions en route.
对于长距离迁徙的鸟类来说，其迁徙的开始被认为主要受内源性控制。最近，气候变化似乎正在促使繁殖地到达时间发生快速变化。然而，对于在迁徙周期中影响候鸟的气候因素，或者最近报道的物候变化是由可塑性行为反应还是进化变化引起的，我们却知之甚少。在这里，我们研究越冬地以及前往繁殖地途中的环境条件如何影响迁徙时间。利用1984年至2004年的数据，这些数据涵盖了每年从中东和北欧的观测站整个迁徙期的情况，我们发现穿越撒哈拉沙漠的时间被推迟，且与越冬地条件的改善相关。相比之下，候鸟在欧洲的飞行速度更快，并根据途中环境条件的改善来调整它们到达繁殖地的时间。以前的研究报告了通过地中海地区（意大利）的不同迁徙路线的相反结果。我们认为，对于不同纬度和不同迁徙路线之间不同物候模式的最简单解释似乎是对途中条件空间变异性的表型反应。
