Computational Geo-ecology, Institute for Biodiversity and Ecosystem Dynamics IBED, University of Amsterdam, Nieuwe Achtergracht 166, Amsterdam, The Netherlands.
Proc Biol Sci. 2010 May 22;277(1687):1505-11. doi: 10.1098/rspb.2009.2112. Epub 2010 Jan 13.
Numerous animals move vast distances through media with stochastic dynamic properties. Avian migrants must cope with variable wind speeds and directions en route, which potentially jeopardize fine-tuned migration routes and itineraries. We show how unpredictable winds affect flight times and the use of an intermediate staging site by red knots (Calidris canutus canutus) migrating from west Africa to the central north Siberian breeding areas via the German Wadden Sea. A dynamic migration model incorporating wind conditions during flight shows that flight durations between Mauritania and the Wadden Sea vary between 2 and 8 days. The number of birds counted at the only known intermediate staging site on the French Atlantic coast was strongly positively correlated with simulated flight times. In addition, particularly light-weight birds occurred at this location. These independent results support the idea that stochastic wind conditions are the main driver of the use of this intermediate stopover site as an emergency staging area. Because of the ubiquity of stochastically varying media, we expect such emergency habitats to exist in many other migratory systems, both airborne and oceanic. Our model provides a tool to quantify the effect of winds and currents en route.
许多动物通过具有随机动态特性的介质远距离迁徙。鸟类迁徙者必须在途中应对变化无常的风速和风向，这可能会危及精细调整的迁徙路线和行程。我们展示了不可预测的风如何影响飞行时间以及红腹滨鹬（Calidris canutus canutus）从西非经由德国的瓦登海迁徙到北西伯利亚中部繁殖区时对中途停留地点的利用。一个整合了飞行过程中风况的动态迁徙模型表明，毛里塔尼亚和瓦登海之间的飞行时间在 2 到 8 天之间变化。在法国大西洋海岸唯一已知的中途停留地点计数的鸟类数量与模拟的飞行时间呈强烈正相关。此外，特别轻量级的鸟类出现在这个地点。这些独立的结果支持了这样一种观点，即随机风况是使用该中途停留点作为紧急停留区的主要驱动因素。由于随机变化的介质无处不在，我们预计这种紧急栖息地在许多其他迁徙系统中，包括空中和海洋中都存在。我们的模型提供了一种工具，可以量化途中风和海流的影响。
