PREDATION DANGER IN THE EVOLUTIONARY ECOLOGY OF MIGRATION

提案摘要 捕食者杀死和消耗猎物，猎物使用防御行为，生理和形态来减少危险。捕食者造成的死亡率（称为“直接威胁”）影响猎物种群，但在猎物中诱导的防御也有影响，称为风险效应。 在过去的20年里，生态学家们有了一个惊人的发现，即风险效应可能与直接死亡一样大，甚至更大。原因是防御（寻求安全）要求猎物减少觅食，更加谨慎，或投资于防御形态，所有这些都需要时间和精力，否则可以用于获得生存和繁殖的资源。尽管这是生态学研究的一个活跃领域，但似乎捕食者的总影响的一半或更多通常可归因于风险效应。因此，引入（或移除）顶级捕食者对生态系统的影响远远超出了被杀死（或幸免）的猎物数量，因为猎物的反应是提高（或降低）它们的防御水平，这反过来又会影响其他营养水平。 所有这一切都体现在现在著名的90年代中期重新引入狼到黄石国家公园。 在20世纪70年代初滴滴涕被禁止后，猛禽（鹰，老鹰，猎鹰）在北美强劲复苏。例如，猎鹰的数量现在至少增加了37倍。 与此同时，其他鸟类种群的数量也大幅下降，这让环保主义者感到震惊，并让他们寻找原因。一般来说，没有强有力的证据指向任何可疑的原因。 与生态学的其他领域相比，鸟类生态学和保护一直缓慢地接受风险效应的概念，猛禽恢复启动了黄石狼重新引入的大陆规模版本的可能性，风险效应（部分）负责鸟类种群的强烈下降，尚未被考虑。这是一个合理的假设，因为对大规模系统的少数研究表明，仅风险效应就足以使人口下降。 我专注于猎鹰和滨鸟，并提出估计的直接杀害和风险影响的相对贡献，自20世纪70年代以来，北美滨鸟普查数字下降了70%。我在过去20年里对猎鹰和长距离迁徙的滨鸟的研究已经确定了一些可能产生风险影响的候选行为，其中一些在理论上似乎足够大，可以解释下降的很大一部分。这些可能性几乎完全没有得到鸟类保护研究界的重视和调查。研究结果将有助于评估风险效应的潜在强大影响，

Summary of proposal Predators kill and consume prey, and prey use defensive behaviour, physiology and morphology to reduce the danger. The mortality that predators inflict (termed direct killing') impacts prey populations, but the defenses induced in prey also have impacts, termed risk effects'. Over the past two decades ecologists have made the surprising discovery that risk effects can be as big or bigger than direct killing. The reason is that defenses (safety-seeking') requires prey to forage less, be more cautious, or to invest in defensive morphology, all of which require time and energy that could otherwise be devoted to acquiring the resources for survival and reproduction. Although an active area of investigation in ecology, it appears that half or more of the total impact of predators can typically be attributed to risk effects. The impacts on ecosystems when top predators are introduced (or removed) therefore extend far beyond the number of prey individuals killed (or spared), because prey respond by raising (or lowering) the level of their defenses, which in turn affects other trophic levels. All of this is exemplified by the now-famous mid-1990s re-introduction of wolves to Yellowstone National Park. Raptor (eagles, hawks, falcons) recovered strongly in North America after DDT was banned in the early 1970s. Falcon numbers, for example, are now at least 3 7-fold higher. At the same time, the numbers in other avian groups have declined strongly, which has alarmed conservationists and sent them searching for causes. Generally, no strong evidence points to any of the suspected reasons. In contrast to other areas in ecology, avian ecology and conservation has been slow to embrace the concept of risk effects, and the possibility that raptor recovery has initiated a continental-scale version of the Yellowstone wolf reintroduction, with risk effects (partially) responsible for the strong declines in bird populations, has not been considered. This is a plausible hypothesis, as the few studies on large-scale systems suggest that the risk effects alone are large enough to send populations into decline. I focus on falcons and shorebirds, and propose to estimate the relative contributions of direct killing and risk effects to the 70% declines registered in North American shorebird census numbers since the 1970s. My studies of falcons and long-distance migratory shorebirds of the past two decades have identified a number of candidate behaviours that could generate risk effects, some of which in theory appear large enough to be able to account for a substantial portion of the decline. These possibilities are almost entirely unappreciated and remain uninvestigated by the avian conservation research community. The results will help conservation work by assessing the potentially strong influence of risk effects