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影响的理论模型只关注直接捕食及其对猎物存活率的影响。然而，当捕食者出现时，大多数被捕食物种会改变它们的行为，以减少被捕食的风险。因为这些行为反应需要时间和精力，它们很可能以应该纳入捕食者-猎物模型的方式影响猎物物种的生存和繁殖。这项研究将通过三种方式检查麋鹿对狼捕食风险的行为反应。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。要研究的行为反应包括放牧模式、个体时间预算、运动模式、空间分布和栖息地选择。然后，它将测试与抗捕食反应相关的生理成本，使用粪便糖皮质激素来测量压力，使用雪尿尿囊素：肌酐比率来测量觅食成功率，使用粪便孕激素来测量怀孕率。(3)最终确定反捕食者行为对生存模式和种群规模变化的影响。将狼重新引入大黄石生态系统后，狼的数量迅速增长，地理范围也在扩大。狼的稳定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、媒体和公众中引起了巨大的争议。这场争论的核心是狼捕食对野生动物种群的潜在影响，尤其是麋鹿。这项研究将产生关于狼捕食率及其对麋鹿人口、分布和动态的影响的大量数据。这些数据将在制定狼和麋鹿管理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.