Behavioral Responses of Elk to Predation by Wolves: Physiological Costs and Dynamical Consequences

大多数关于捕食者对猎物种群的影响的理论模型都专注于直接摄取及其对猎物存活率的影响。然而，当捕食者出现时，大多数猎物物种会改变自己的行为，以降低捕食的风险。由于这些行为反应需要时间和精力，它们可能会影响被捕食物种的生存和繁殖，这种方式应该被纳入捕食者-猎物模型中。这项研究将从三个方面考察麋鹿对狼捕食风险的行为反应。(1)最根本的是，它将测试麋鹿对狼捕食风险的时空变化的行为反应。被检查的行为反应包括群体模式、个体时间预算、运动模式、空间分布和栖息地选择。(2)然后，它将测试与反捕食者反应相关的生理成本，使用粪便糖皮质激素来衡量压力，使用雪尿尿囊素：肌酐比率来衡量觅食成功，使用粪便孕激素来衡量怀孕率。(3)最后，它将确定反捕食者行为对生存模式和种群数量变化的影响。将狼重新引入大黄石生态系统后，狼的数量迅速增长，并在地理上不断扩大。狼的稳步增长和扩张在野生动物管理者、保护生物学家、州和联邦立法者、媒体和普通公众中引起了巨大的争议。这场争论的核心是狼的捕食对野生动物种群的潜在影响，特别是麋鹿。这项研究将产生大量关于狼的捕食率及其对麋鹿人口统计、分布和动态的影响的数据。这些数据将在制定管理狼和麋鹿的政策方面发挥关键作用。

Most theoretical models of the impact that predators have on prey populations focus exclusively on direct offtake and its impact on the survival rate of prey. However, most prey species modify their behavior when predators are present, to reduce the risk of predation. Because these behavioral responses require time and energy, they are likely to affect the survival and reproduction of prey species in ways that should be incorporated into predator-prey models. This research will examine the behavioral responses of elk to the risk of predation by wolves, in three ways. (1) Most fundamentally, it will test for behavioral responses of elk to spatial and temporal variation in the risk of predation by wolves. The behavioral responses to be examined include patterns of herding, individual time budgets, movement patterns, spatial distributions, and habitat selection. (2) It will then test for physiological costs associated with antipredator responses, using fecal glucocorticoids to measure stress, snow-urine allantoin:creatinine ratios to measure foraging success, and fecal progestins to measure pregnancy rates. (3) Finally, it will determine the impacts of antipredator behavior on patterns of survival and changes in population size. The reintroduction of wolves to the Greater Yellowstone Ecosystem has produced a rapidly growing and geographically expanding population. The steady growth and expansion of wolves has generated enormous controversy among wildlife managers, conservation biologists, state and federal lawmakers, the media, and the general public. Sitting at the heart of this controversy is the potential impact of wolf predation on wildlife populations, particularly elk. This research will produce substantial data on rates of wolf predation and its effects on elk demography, distribution and dynamics. These data will play a critical role in establishing policies for the management of wolves and elk.