PREDATION DANGER IN THE ECOLOGY OF MIGRATION

迁徙生态中的捕食危险 顶级捕食者对猎物种群产生强大的影响。正如重新引入狼在黄石公园生态系统中引起的变化所表明的那样，这些影响可以通过被捕食动物的反捕食者行为传播到整个社区。自1973年(DDT被禁止)以来猛禽种群的强劲复苏是黄石公园狼重新引入的大陆版本，表明类似的影响是可以预期的。在最近的NSERC DGs中，我发现顶级捕食者(隼属的猎鹰)强烈地影响着Calidris属的琵琶的生态和迁徙的进化。我在这里提出的项目延续了这一研究路线，研究反捕食者行为是否在它们与迁徙有关的生物学其他方面发挥了作用。 像许多其他鸟类迁徙一样，西部琵鹭(Calidris Mauri)表现出强烈的非繁殖性别隔离。捕食风险是否会影响非繁殖区的扩散？我建议检验最初针对有蹄类动物提出的“捕食风险”假说。该假说预测，更脆弱的性别成员要付出代价(距离更远)才能迁徙到更安全的非繁殖地点。 翅膀的展宽比(宽/长)对飞行性能有很大影响，长翅膀更有利于能量效率，宽翅膀更有利于快速起飞和敏捷，这是躲避捕食者的重要特征。数据显示，自1980年以来，半交配琵鹭(Calidris Pusilla)的翅膀长度急剧缩短。我建议测试一个假设，即随着猎鹰种群的恢复，自然选择产生了更具防御性的飞行形态，这是导致这种形态转变的原因。 种群动力学的研究当然考虑了捕食行为，但反捕食者行为的作用几乎没有受到关注。我发现，尽管猎鹰的数量增加了3-7倍，但在过去的36年里，非繁殖的杜松鼠(Calidris Alpina)的种群动态并没有受到猎鹰的影响。我建议测试一种假设，即土拨鼠转向更具防御性的非繁殖行为(类似于上面的翅膀长度变化)，以补偿的方式调节了捕食者和饥饿的影响。 最后，我建议继续我对红眼鲑鱼Oncoryhnchus Nerka的工作。捕食危险在鲑鱼迁徙的生态和进化中的作用很少被考虑。在不列颠哥伦比亚省，红眼种群在上游产卵迁移的时间上有很大的差异，这种模式可以用温度对成虫和孵化代谢的影响来解释。我建议测试一种假设，即选择河流进入的时机是为了避免接触到熊等捕食者。

PREDATION DANGER IN THE ECOLOGY OF MIGRATION Top predators exert powerful effects on prey populations. As exemplified by the changes induced in the Yellowstone ecosystem by the reintroduction of wolves, these effects can ripple throughout entire communities, transmitted via the anti-predator behavior of prey animals. The strong recovery of raptor populations since 1973 (when DDT was banned) is a continental scale version of the Yellowstone wolf reintroduction, and suggests that analogous impacts are to be expected. In recent NSERC DGs, I found that top predators (falcons of the genus Falco) strongly impact the ecology and evolution of migration in sandpipers of the genus Calidris. The projects I propose here continue this line of inquiry, asking whether anti-predator behavior plays a role in other aspects of their biology linked to migration. Like many other avian migrants, the western sandpiper (Calidris mauri) shows strong nonbreeding sexual segregation. Does predation risk affect dispersion over non-breeding areas? I propose to test the ‘predation risk’ hypothesis, originally put forward for ungulates. The hypothesis predicts that members of the more vulnerable sex pay a cost (greater distance) to migrate to safer nonbreeding sites. The aspect ratio (width/length) of wings greatly affects flight performance, with long wings better for energetic efficiency, and wide wings better for rapid take-off and agility, traits important in eluding predators. Data show that the wing length of semipalmated sandpipers (Calidris pusilla) has shortened dramatically since 1980. I propose to test the hypothesis that natural selection for more defensive flight morphology, created as falcon populations recovered, is responsible for this morphological shift. The study of population dynamics has of course considered predation, but the role of anti-predator behavior has received little attention. I have found that the population dynamics of nonbreeding dunlins (Calidris alpina) has not been affected by falcons over the past 36 years, even though falcon numbers have increased 3-7 fold. I propose to test the hypothesis that a shift by dunlins toward more defensive non-breeding behavior (analogous to the wing length shift above) has mediated the effects of predators and starvation in a compensatory fashion. Finally, I propose to continue my work on sockeye salmon Oncoryhnchus nerka. The role of predation danger in the ecology and evolution of salmon migration has rarely been considered. In British Columbia, sockeye populations differ greatly in the timing of their up-river spawning migrations, a pattern classically explained by the effects of temperature on adult and incubation metabolism. I propose to test the hypothesis that river-entry timing is selected for to avoid exposure to predators such as bears.