Partial migration of elk in a heterogeneous landscape

迁徙是自然界最具标志性的过程之一。 了解部分迁移的维持，其中只有一部分人口迁移，最近引起了人口生态学家的注意，但也因为面临气候变化和人类足迹不断增长的迁移系统的巨大变化而引起了保护主义者的注意。 了解部分迁移的维持从根本上需要长期的人口监测，以区分其维持的假设，但长期的研究部分迁移有蹄类动物是非常罕见的。 在接下来的5年里，我的研究团队扩展了我们对阿尔伯塔班夫国家公园附近部分迁徙麋鹿（马鹿）种群的13年人口统计学研究。 我们建立在我们过去的研究比较行为，空间使用和人口迁移段解决3个新的问题。首先，最近的理论表明，环境条件的空间和时间变化强烈影响个体适应性的方式，可能有相反的影响在人口水平。 我们问在什么程度上可以抵消随机变化的发病率，变化率和生长季节（物候）的持续时间的趋势，推动牧草质量在大规模的栖息地条件的局部空间变化。 这是一个在大型食草动物觅食生态学中没有得到很好研究的领域。 其次，我们扩大我们的重点从狼捕食者社区的自上而下的影响，并询问如何大的食肉动物的相互作用影响的时空模式捕食风险麋鹿在3个时期（产犊，夏末和冬季），对食草动物施加不同的运动和营养限制。第三，对哺乳动物的研究数据不足，表明迁移策略之间的转换很少，这表明它们是固定的。在这个系统中，麋鹿的遗传数据并不支持这一点，经过13年的转换，现在平均每年转换16%（3-25%），这意味着比我们最初认为的更大的作用。 我们现在假设，部分迁移是由密度依赖的健身平衡和切换。为了评估这一假设，我们首先需要确定是否内在（年龄，学习）或外在因素（捕食风险，饲料质量）影响开关。我们计划建立空间和aspatial人口模型，以评估部分迁移背后的机制，并说明这些方法可以帮助制定当地的管理和全球战略，保护环境变化下的迁移人口。

Migration is one of nature's most iconic processes. Understanding the maintenance of partial migration, where only a portion of the population migrates, has caught the recent attention of population ecologists, but also conservationists because of the dramatic changes in migratory systems facing climate change and a growing human foot print. Understanding the maintenance of partial migration fundamentally requires long-term demographic monitoring to distinguish among hypotheses for its maintenance, but long-term studies on partially migratory ungulates are exceedingly rare. In the next 5 years, my research team extends our 13-year demographic study of a partially migratory elk (Cervus elaphus) population near Banff National Park, Alberta. We build on our past research comparing behavior, space use, and demography among migratory segments addressing 3 new questions. First, recent theory indicates spatial and temporal variation in environmental conditions strongly affects individual fitness in ways that may have opposing effects at the population level. We ask to what extent can local spatial variation in habitat conditions off-set stochastic variation in the onset, rate of change, and duration of growing season (phenological) trends that drive forage quality at the large-scale. This is an area not well studied in the foraging ecology of large herbivores. Second, we expand our focus on the top-down effects from wolves to predator communities and ask how large carnivore interactions influence the spatiotemporal patterns in predation risk for elk during 3 periods (calving, late summer and winter) that impose different movement and nutritional constraints on herbivores. Third, scant data from studies on mammals indicate switching among migratory strategies is rare, pointing to them being fixed. Genetic data from elk in this system do not support this, and after 13 years switching now averages 16% (3-25%) per year, implicating a bigger role than we originally argued. We now hypothesize that partial migration is maintained by density-dependent fitness balancing and switching. To evaluate this hypothesis we first need to determine whether intrinsic (age, learning) or extrinsic factors (predation risk, forage quality) influence switching. We plan to build spatial and aspatial demographic models to evaluate the mechanisms behind partial migration and illustrate how these approaches can help devise local management and global strategies for conserving migratory populations under environmental change.