Animal Behaviour and Welfare Research Group, Department of Biological Sciences, University of Chester, Chester CH1 4BJ, UK.
Institute of Conservation Science & Learning, Bristol Zoological Society, Clifton, Bristol BS8 3HA, UK.
Horm Behav. 2022 Aug;144:105228. doi: 10.1016/j.yhbeh.2022.105228. Epub 2022 Jun 27.
A critical component of conserving and housing species ex situ is an explicit scientific understanding of the physiological underpinnings of their welfare. Cortisol has been repeatedly linked to stress, and therefore used as an indicator of welfare for many species. In order to measure cortisol in the Livingstone's fruit bat (Pteropus livingstonii; a critically endangered keystone species) without disturbing the captive population, we have developed and validated a non-invasive, novel hormone extraction procedure and faecal glucocorticoid assay. A total of 92 faecal samples, 73 from the P. livingstonii breeding colony at Jersey Zoo, Channel Islands and 19 samples from P. livingstonii housed at Bristol Zoological Gardens, UK, have been collected and analyzed. Mixed-effect modelling of the influence of physiological state variables on cortisol concentration revealed that lactating females had higher cortisol levels than non-lactating females, indicating that our assay is measuring biologically relevant hormone concentrations. Males and older bats also had higher cortisol than non-lactating females and younger individuals. Further analysis applied social network methodology to compare the cortisol levels of bats with different social roles. We found that individuals that linked social groups possessed higher than average cortisol levels and conversely, individuals with high-quality, positive relationships had lower cortisol levels. These results demonstrate, for the first time in a bat species, social mediation of stress hormones. Lastly, the frequency of vocalisation was found to positively correlate with cortisol concentration in males, suggesting that this behaviour may be used by animal management as a visual indicator of a bat's hormonal status. Hence, this research has provided unique insights and empirical scientific knowledge regarding the relationship between the physiology and social behaviour of P. livingstonii, therefore allowing for recommendations to be made to optimise bat welfare at the individual level.
保护和饲养物种的一个关键组成部分是对其福利的生理基础有明确的科学认识。皮质醇与应激反复相关联，因此被许多物种用作福利的指标。为了在不干扰圈养种群的情况下测量利文斯顿氏果蝠（濒临灭绝的关键物种 Pteropus livingstonii）中的皮质醇，我们开发并验证了一种非侵入性的、新颖的激素提取程序和粪便糖皮质激素测定法。共收集和分析了 92 份粪便样本，其中 73 份来自泽西动物园（泽西岛，海峡群岛）的 P. livingstonii 繁殖群，19 份来自英国布里斯托动物园的 P. livingstonii 圈养群。对生理状态变量对皮质醇浓度的影响进行混合效应建模表明，哺乳期雌性的皮质醇水平高于非哺乳期雌性，这表明我们的测定法正在测量具有生物学意义的激素浓度。雄性和较老的蝙蝠的皮质醇水平也高于非哺乳期雌性和较年轻的个体。进一步的分析应用社会网络方法比较了具有不同社会角色的蝙蝠的皮质醇水平。我们发现，与社会群体联系的个体的皮质醇水平高于平均水平，反之，具有高质量、积极关系的个体的皮质醇水平较低。这些结果首次在蝙蝠物种中证明了社会对应激激素的调节作用。最后，发现雄性的发声频率与皮质醇浓度呈正相关，这表明这种行为可能被动物管理部门用作蝙蝠激素状态的视觉指标。因此，这项研究首次提供了关于 P. livingstonii 生理和社会行为之间关系的独特见解和经验科学知识，从而为优化个体水平的蝙蝠福利提供了建议。
