Quantifying hair cortisol has become popular in wildlife ecology for its practical advantages for evaluating stress. Before hair cortisol levels can be reliably interpreted, however, it is key to first understand the intrinsic factors explaining intra- and inter-specific variation. Bats are an ecologically diverse group of mammals that allow studying such variation. Given that many bat species are threatened or have declining populations in parts of their range, minimally invasive tools for monitoring colony health and identifying cryptic stressors are needed to efficiently direct conservation efforts. Here we describe intra- and inter-specific sources of variation in hair cortisol levels in 18 Neotropical bat species from Belize and Mexico. We found that fecundity is an important ecological trait explaining inter-specific variation in bat hair cortisol. Other ecological variables such as colony size, roost durability and basal metabolic rate did not explain hair cortisol variation among species. At the individual level, females exhibited higher hair cortisol levels than males and the effect of body mass varied among species. Overall, our findings help validate and accurately apply hair cortisol as a monitoring tool in free-ranging bats.

中文翻译：

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新热带蝙蝠毛发皮质醇浓度的种间和种内变化

量化头发皮质醇因其在评估压力方面的实际优势而在野生动物生态学中变得流行。然而，在能够可靠地解释头发皮质醇水平之前，首先了解解释种内和种间变异的内在因素是关键。蝙蝠是一组生态多样的哺乳动物，可以研究这种变异。鉴于许多蝙蝠物种受到威胁或在其部分范围内的种群数量下降，需要用于监测群体健康和识别神秘压力源的微创工具来有效地指导保护工作。在这里，我们描述了来自伯利兹和墨西哥的 18 种新热带蝙蝠物种的毛发皮质醇水平变化的内部和内部特定来源。我们发现繁殖力是一个重要的生态特征，解释了蝙蝠毛发皮质醇的种间变异。其他生态变量，如菌落大小、栖息地耐久性和基础代谢率并不能解释物种间毛发皮质醇的变化。在个体水平上，女性表现出比男性更高的头发皮质醇水平，并且体重的影响因物种而异。总体而言，我们的研究结果有助于验证并准确地将毛发皮质醇用作自由放养蝙蝠的监测工具。