DISSERTATION RESEARCH: Indirect Effects of Predators on Prey: Consequences of Wolf Predation for Elk behavio, Nutrition, and Reproduction

捕食者对猎物种群的总影响包括杀死猎物和与反捕食者行为相关的不那么明显的代价。这些成本经常影响猎物的生存或繁殖，并可能成为实验中种群动态的重要组成部分。然而，要在野外揭示这些行为的代价是困难的，因为捕食风险往往会随着时间和空间的变化而发生不可预测的变化。联邦重新引入狼和保护计划导致北美几个地区的狼数量迅速增长和广泛扩张。这些新的狼种群已经引起了几个高度公开的争议，特别是在被狼捕食的动物为当地社区提供娱乐和收入的重要来源的景观中。在蒙大拿州的加拉丁峡谷，在狼群重新定居后，麋鹿的数量和招募数量立即显示出显著的下降水平，直接捕食似乎只是部分原因。尽管可能涉及冬季生存，但怀孕率和幼崽存活率表明，麋鹿的繁殖也可能受到最近狼的到来的影响。这项研究表明，当狼在附近时，麋鹿会分裂成较小的群体，在针叶林中花费更多的时间，迁移到更高的海拔，提高警惕，并减少在开阔地区的放牧。因此，与躲避狼相关的成本可能是存在的，可能是麋鹿种群的一个重要因素。这项研究将记录狼群在整个冬天穿越加拉丁峡谷时，三个不同的麋鹿群的觅食行为、饮食组成和饮食营养。每天狼的位置和捕杀频率将被监测，以便每个麋鹿群的行为和营养数据可以与不同水平的捕食风险联系起来。最后，不同麋鹿群在条件、生存和繁殖成功方面的差异将与对狼的行为反应有关。除了为研究生完成工作提供经济支持和为本科生提供教育经验外，这些数据还将有助于我们理解在风险自然变化的情况下，反捕食者行为在种群动态中的作用。

The total impact of predators on prey populations includes the killing of prey and the less conspicuous costs associated with antipredator behavior. These costs often affect prey survival or reproduction and can be an important part of population dynamics in experiments. However, uncovering the costs of these behaviors in the wild is difficult because predation risk tends to vary unpredictably over time and space. Federal wolf reintroduction and conservation programs have resulted in rapidly growing and widely expanding populations in several areas of North America. These new wolf populations have generated several highly publicized controversies, especially in landscapes where animals preyed upon by wolves provide an important source of recreation and revenue for local communities. In the Gallatin Canyon of Montana, elk population size and recruitment showed significantly depressed levels immediately following recolonization by wolves, and direct predation appears only partly responsible. Although winter survival may be involved, pregnancy rates and calf survival suggest elk reproduction might also be influenced by the recent arrival of wolves. This study has shown that elk will break into smaller groups, spend more time in conifer forest, move to higher elevations, increase their level of vigilance, and decrease grazing in open areas when wolves are nearby. Thus, costs associated with avoiding wolves likely exist and are probably an important factor for elk populations. This study will record foraging behavior, diet composition, and dietary nutrition in three separate herds of elk as wolves move across the Gallatin Canyon throughout the winter. Daily wolf locations and frequency of kills will be monitored so that behavioral and nutritional data for each elk herd can be linked to differing levels of predation risk. Finally, differences in condition, survival, and reproductive success between elk herds will be associated with behavioral responses to wolves. In addition to providing financial support for a graduate student to complete the work and an educational experience for undergraduates, these data will contribute substantially to our understanding of the role of antipredator behavior in population dynamics under natural variation in risk.