Partial migration of elk in a heterogeneous landscape

麋鹿在异质景观中的部分迁徙

• 批准号: RGPIN-2016-04733
• 负责人: Merrill, Evelyn
• 金额: $ 4.52万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=709448
• 关键词: Partial; migration; elk; heterogeneous; landscape

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.

迁徙是自然界最具标志性的过程之一。 了解部分迁徙的维持（即只有一部分人口迁徙）最近引起了人口生态学家和自然资源保护主义者的关注，因为迁徙系统面临气候变化和人类足迹不断增加的巨大变化。 了解部分迁徙的维持从根本上需要长期的人口统计监测来区分其维持的假设，但对部分迁徙有蹄类动物的长期研究极其罕见。 在接下来的 5 年里，我的研究团队将继续对艾伯塔省班夫国家公园附近的部分迁徙麋鹿 (Cervus elaphus) 种群进行 13 年的人口统计研究。 我们以过去的研究为基础，对迁徙群体的行为、空间利用和人口统计进行比较，解决了 3 个新问题。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的健康，而这可能会在人口层面产生相反的影响。 我们询问栖息地条件的局部空间变化在多大程度上可以抵消生长季节（物候）趋势的开始、变化率和持续时间的随机变化，从而大规模地推动饲料质量。 这是大型食草动物觅食生态学中尚未得到充分研究的领域。 其次，我们将重点放在从狼到捕食者群落的自上而下的影响上，并询问食肉动物的相互作用如何影响麋鹿在三个时期（产犊、夏末和冬季）的捕食风险时空模式，这三个时期施加了不同的运动和营养限制关于食草动物。第三，对哺乳动物的研究数据很少表明，迁徙策略之间的转换很少见，这表明它们是固定的。该系统中麋鹿的遗传数据并不支持这一点，13 年后的转换现在平均每年 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通过密度依赖的适应度平衡和切换来维持的。为了评估这个假设，我们首先需要确定内在因素（年龄、学习）或外在因素（捕食风险、饲料质量）是否影响转换。我们计划建立空间和空间人口模型来评估部分移民背后的机制，并说明这些方法如何帮助制定地方管理和全球战略，以在环境变化下保护移民人口。