Whipple Ashley L, Ray Chris, Wasser Max, Kitchens James N, Hove Alisa A, Varner Johanna, Wilkening Jennifer L
Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA.
Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80303, USA.
Conserv Physiol. 2021 May 3;9(1):coab024. doi: 10.1093/conphys/coab024. eCollection 2021.
Temporal variation in stress might signify changes in an animal's internal or external environment, while spatial variation in stress might signify variation in the quality of the habitats that individual animals experience. Habitat-induced variations in stress might be easiest to detect in highly territorial animals, and especially in species that do not take advantage of common strategies for modulating habitat-induced stress, such as migration (escape in space) or hibernation (escape in time). Spatial and temporal variation in response to potential stressors has received little study in wild animals, especially at scales appropriate for relating stress to specific habitat characteristics. Here, we use the American pika (), a territorial small mammal, to investigate stress response within and among territories. For individually territorial animals such as pikas, differences in habitat quality should lead to differences in stress exhibited by territory owners. We indexed stress using stress-associated hormone metabolites in feces collected non-invasively from pika territories every 2 weeks from June to September 2018. We hypothesized that differences in territory quality would lead to spatial differences in mean stress and that seasonal variation in physiology or the physical environment would lead to synchronous variation across territories through time. We used linear mixed-effects models to explore spatiotemporal variation in stress using fixed effects of day-of-year and broad habitat characteristics (elevation, aspect, site), as well as local variation in habitat characteristics hypothesized to affect territory quality for this saxicolous species (talus depth, clast size, available forage types). We found that temporal variation within territories was greater than spatial variation among territories, suggesting that shared seasonal stressors are more influential than differences in individual habitat quality. This approach could be used in other wildlife studies to refine our understanding of habitat quality and its effect on individual stress levels as a driver of population decline.
应激的时间变化可能意味着动物内部或外部环境的变化，而应激的空间变化可能意味着个体动物所经历的栖息地质量的变化。在具有高度领地意识的动物中，尤其是在那些不采用常见策略来调节栖息地引起的应激的物种中，例如迁徙（空间上的逃避）或冬眠（时间上的逃避），栖息地引起的应激变化可能最容易被检测到。野生动物对应激源的空间和时间变化的研究很少，尤其是在适合将应激与特定栖息地特征联系起来的尺度上。在这里，我们以美洲鼠兔（一种具有领地意识的小型哺乳动物）为研究对象，来调查领地内部和领地之间的应激反应。对于像鼠兔这样具有个体领地意识的动物来说，栖息地质量的差异应该会导致领地所有者表现出的应激差异。我们通过在2018年6月至9月期间每两周从鼠兔领地非侵入性收集的粪便中，使用与应激相关的激素代谢物来衡量应激水平。我们假设领地质量的差异会导致平均应激的空间差异，并且生理或物理环境的季节性变化会导致不同领地随时间同步变化。我们使用线性混合效应模型，通过一年中的日期和宽泛的栖息地特征（海拔、坡向、地点）的固定效应，以及假设会影响这种岩栖物种领地质量的栖息地特征的局部变化（岩屑深度、岩块大小、可用的食物类型），来探索应激的时空变化。我们发现领地内的时间变化大于领地间的空间变化，这表明共同的季节性应激源比个体栖息地质量的差异更具影响力。这种方法可用于其他野生动物研究，以深化我们对栖息地质量及其作为种群数量下降驱动因素对个体应激水平影响的理解。
