When and where mortality occurs throughout the annual cycle changes with age in a migratory bird: individual vs population implications
When and where mortality occurs throughout the annual cycle changes with age in a migratory bird: individual vs population implications
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候鸟在整个年度周期中死亡发生的时间和地点随着年龄的变化而变化：个体与种群的影响
作者：
F. Sergio;G. Tavecchia;A. Tanferna;J. Blas;G. Blanco;F. Hiraldo
大多数动物的年周期都分为几个不连续的阶段，如繁殖、迁徙和扩散。虽然人们越来越认识到生物体年周期的不同阶段对其健康和种群动态的重要性，但几乎不知道这种季节性影响是否以及如何在物种寿命期间发生变化。在这里，我们利用长期卫星/GPS跟踪研究和可靠的远程死亡检测方法提供的机会，表明迁徙长寿猛禽黑鸢Milvus migrans的年度和生命周期的某些阶段可能代表生存的敏感瓶颈。特别是，迁徙的旅程造成了集中死亡率的爆发整个生命，但阶段特异性生存的相对重要性随着年龄的变化。另一方面，短期的高死亡率和长期的低死亡率之间的平衡使得人口增长同样依赖于年周期的所有部分。我们的研究结果说明了迁移生物的种群动态如何与平衡在多个阶段的年度周期，从而多个领域的地球仪的生态压力密不可分，这表明经常需要具有挑战性的保护策略，针对所有部分的物种全年范围。
The annual cycle of most animals is structured into discrete stages, such as breeding, migration and dispersal. While there is growing appreciation of the importance of different stages of an organism’s annual cycle for its fitness and population dynamics, almost nothing is known about if and how such seasonal effects can change through a species lifespan. Here, we take advantage of the opportunity offered by a long-term satellite/GPS-tracking study and a reliable method of remote death-detection to show that certain stages of both the annual and life cycle of a migratory long-lived raptor, the Black kite Milvus migrans, may represent sensitive bottlenecks for survival. In particular, migratory journeys caused bursts of concentrated-mortality throughout life, but the relative importance of stage-specific survival changed with age. On the other hand, the balance between short-stages of high mortality and long-stages of low mortality made population-growth similarly dependent on all portions of the annual cycle. Our results illustrate how the population dynamics of migratory organisms can be inextricably linked to ecological pressures balanced over multiple stages of the annual cycle and thus multiple areas of the globe, suggesting the frequent need for challenging conservation strategies targeting all portions of a species year-round range.