Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark.
Department of Biology, Lund University, Ecology Building, SE-22362 Lund, Sweden.; Dutch Montagu's Harrier Foundation, P.O. Box 46, 9679ZG Scheemda, Netherlands.; Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, P.O. Box 11103, 9700CC Groningen, Netherlands.
Sci Adv. 2017 Jan 4;3(1):e1601360. doi: 10.1126/sciadv.1601360. eCollection 2017 Jan.
Migratory birds track seasonal resources across and between continents. We propose a general strategy of tracking the broad seasonal abundance of resources throughout the annual cycle in the longest-distance migrating land birds as an alternative to tracking a certain climatic niche or shorter-term resource surplus occurring, for example, during spring foliation. Whether and how this is possible for complex annual spatiotemporal schedules is not known. New tracking technology enables unprecedented spatial and temporal mapping of long-distance movement of birds. We show that three Palearctic-African species track vegetation greenness throughout their annual cycle, adjusting the timing and direction of migratory movements with seasonal changes in resource availability over Europe and Africa. Common cuckoos maximize the vegetation greenness, whereas red-backed shrikes and thrush nightingales track seasonal surplus in greenness. Our results demonstrate that the longest-distance migrants move between consecutive staging areas even within the wintering region in Africa to match seasonal variation in regional climate. End-of-century climate projections indicate that optimizing greenness would be possible but that vegetation surplus might be more difficult to track in the future.
候鸟在各大洲之间追踪季节性资源。我们提出了一种在最长距离迁徙的陆地鸟类中追踪全年资源广泛季节性丰度的一般策略，以替代追踪特定气候生态位或更短期的资源过剩，例如在春季树叶生长期间。对于复杂的年度时空时间表，这种方法是否可行以及如何实现尚不清楚。新的跟踪技术使鸟类长距离运动的时空映射成为可能。我们表明，三种古北-非洲物种在其全年的周期中追踪植被的绿色度，根据欧洲和非洲资源可用性的季节性变化，调整迁徙运动的时间和方向。普通杜鹃最大限度地利用植被的绿色度，而红背伯劳和夜莺则追踪绿色度的季节性过剩。我们的研究结果表明，最长距离的迁徙者甚至在非洲的越冬区之间的连续中途停留区之间移动，以适应区域气候变化的季节性变化。本世纪末的气候预测表明，优化绿色度是可能的，但未来可能更难以追踪植被的过剩。
