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 (Ochotona princeps), 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.

中文翻译：

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气候敏感小型哺乳动物种群中压力相关代谢物的时间与空间变化

压力的时间变化可能意味着动物内部或外部环境的变化，而压力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。栖息地引起的压力变化可能最容易在具有高度地域性的动物中检测到，尤其是在不利用常见策略来调节栖息地引起的压力的物种中，例如迁徙（太空逃生）或冬眠（及时逃生） . 对潜在压力源的时空变化在野生动物中的研究很少，特别是在适合将压力与特定栖息地特征联系起来的尺度上。在这里，我们使用美洲鼠兔 (Ochotonaprinceps)，一种领土小型哺乳动物，来研究领土内和领土之间的压力反应。对于像鼠兔这样的个体领地动物，栖息地质量的差异应该导致领地所有者表现出的压力差异。从 2018 年 6 月到 2018 年 9 月，我们每 2 周从鼠兔领地非侵入性收集粪便中的压力相关激素代谢物对压力进行索引。我们假设领地质量的差异会导致平均压力的空间差异，以及生理学的季节性变化或物理环境会随着时间的推移导致跨地域的同步变化。我们使用线性混合效应模型来探索压力的时空变化，利用一年中的一天和广泛的栖息地特征（海拔、坡向、地点）的固定效应，以及假设的栖息地特征的局部变化会影响这种 sixicorous 物种的领土质量（距骨深度，碎屑大小，可用草料类型）。我们发现区域内的时间变化大于区域之间的空间变化，这表明共享的季节性压力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，以完善我们对栖息地质量及其对个体压力水平的影响的理解，作为人口下降的驱动因素。