Data from: Fat and happy in the city: eastern chipmunks in urban environments

Cities are rapidly expanding, and wildlife may experience different selection pressures in urban environments when compared to natural habitats. Phenotypic differences between urban and natural populations may occur because of the altered urban environment. Behavior, the activity of the hypothalamic-pituitary-adrenal (HPA) axis and body condition can be expected to differ between urban and natural habitats. We used the eastern chipmunk (Tamias striatus) to test for differences in behavior assayed from an open field test, hair and fecal cortisol concentrations, and body condition (size-corrected body mass), predicting that urban chipmunks would exhibit more exploratory behavior, higher cortisol concentrations, and higher body condition, than their counterparts from natural habitats. We sampled eastern chipmunks in two urban areas paired with natural habitats and subjected adult chipmunks to an open field test, collected hair and fecal samples for the determination of cortisol concentrations, and measured body size and body mass to estimate body condition. Eastern chipmunks in urban habitats had significantly different behavior, tending toward reduced locomotion and grooming, and greater latency, than their counterparts from natural habitats. Urban chipmunks also had lower fecal cortisol concentrations than those from natural habitats, and female chipmunks were in better body condition when captured in urban habitats. These results suggest that urban habitats may be relatively benign for urban chipmunks, perhaps because of reduced need for exploration and the availability of anthropogenic food subsidies associated with urban environments.

城市正快速扩张，相较于自然栖息地，野生动物在城市环境中可能面临不同的选择压力。
城市与自然种群间的表型差异，可能因城市环境的改变而产生。
行为、下丘脑-垂体-肾上腺（hypothalamic-pituitary-adrenal, HPA）轴活性以及身体状况，在城市与自然栖息地间预计会存在差异。
本研究以东部花栗鼠（*Tamias striatus*）为研究对象，通过旷场实验（open field test）、毛发与粪便皮质醇（cortisol）浓度以及身体状况（体型校正体重，size-corrected body mass）来检测行为差异，预测城市花栗鼠相较于自然栖息地的同类，会表现出更强的探索行为、更高的皮质醇浓度以及更佳的身体状况。
我们在两处与自然栖息地配对的城市区域采集东部花栗鼠样本，对成年花栗鼠开展旷场实验，收集毛发与粪便样本以检测皮质醇浓度，并测量体型与体重以估算身体状况。
相较于自然栖息地的同类，城市栖息地的东部花栗鼠行为存在显著差异：其运动与理毛行为减少，潜伏期更长。
城市花栗鼠的粪便皮质醇浓度也低于自然栖息地的花栗鼠，且在城市栖息地捕获的雌性花栗鼠身体状况更佳。
上述结果表明，城市栖息地对东部花栗鼠而言相对友好，这可能是因为城市环境中探索需求降低，且存在与城市环境相关的人为食物补贴。