PREDATION DANGER IN THE ECOLOGY OF MIGRATION

迁徙生态中的捕食危险******上层捕食者对猎物种群有强大的影响。正如狼的重新引入在黄石生态系统中引起的变化所例证的那样，这些影响可以通过被捕食动物的反捕食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恢复是黄石狼重新引入的大陆规模版本，并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（Falco属的猎鹰）强烈影响Calidris属矶鹞的生态和进化迁徙。我在这里提出的项目继续了这条调查路线，询问反捕食者行为是否在与迁徙有关的生物学的其他方面发挥作用。******像许多其他候鸟一样，西部矶鹬（Calidris mauri）表现出强烈的非繁殖性隔离。捕食风险会影响非繁殖区的分散吗？我提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，弱势性别的成员要付出代价（更远的距离）才能迁移到更安全的非繁殖地。******翅膀的长宽比（宽度/长度）极大地影响着飞行性能，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性，这些特征对躲避捕食者很重要。资料显示，自1980年以来，半翅矶鹬（Calidris pusilla）的翅膀长度急剧缩短。我提议测试这样一种假设，即随着猎鹰种群的恢复，自然选择产生了更多的防御性飞行形态，这是造成这种形态转变的原因。******种群动态的研究当然考虑了捕食行为，但反捕食行为的作用却很少受到关注。我发现，在过去的36年里，尽管猎鹰的数量增加了3-7倍，但非繁殖的dunlins （Calidris alpina）的种群动态并没有受到猎鹰的影响。我建议测试这样一个假设，即dunlins向更具防御性的非繁殖行为的转变（类似于上面的翅膀长度变化）以一种补偿性的方式调解了捕食者和饥饿的影响。******最后，我建议继续我对红鲑鱼Oncoryhnchus nerka的研究。捕食危险在鲑鱼洄游的生态学和进化中的作用很少被考虑。在不列颠哥伦比亚省，红鲑种群在上游产卵迁徙的时间上差异很大，这种模式通常由温度对成虫和孵化代谢的影响来解释。我建议测试这样一个假设，即选择入河时间是为了避免暴露于熊等捕食者。**

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. **