Data from: Do wild ungulates experience higher stress with humans than with large carnivores?

Predation is a major selective pressure for prey; however, the stress response to predation risk and the relative importance of natural versus anthropogenic stress factors in wild populations of animals have rarely been studied. We investigated the level of fecal glucocorticoid metabolites (FGMs) in 6 populations of red deer and roe deer exposed to potentially different levels of stress, resulting from both natural (predator presence, forest cover, undergrowth, ungulate density, and temperature) and anthropogenic (hunting harvest, percentage of build-up areas, and road density) factors. We found the highest and most variable FGM concentrations in both ungulates in areas without large carnivores, and the lowest and least variable FGM levels in areas with wolf and lynx. Anthropogenic factors (hunting harvest, roads, and built-up area) positively correlated with the gradient of FGM levels in both species. Both the mean and the variance of the FGM concentrations measured within populations of both red deer and roe deer were affected positively by variation in hunting harvest and negatively by the minimum temperature. The variance in the roe deer FGM was also positively influenced by the percentage of built-up areas. The results indicate that stress in wild ungulate populations is lower and less variable in areas utilized by large carnivores than in carnivore-free areas where human-related factors predominate. This may be explained by evolutionary adaptations of prey animals constantly exposed to the risk of natural predation and their inability of adapting to the risk from humans probably due to its high intensity and erratic occurrence.捕食是猎物演化所面临的主要选择压力之一，但目前针对野生动物种群中捕食风险诱发的应激反应，以及自然应激因子与人为应激因子的相对重要性，相关研究仍较为匮乏。本研究针对6个马鹿与狍子种群的粪便糖皮质激素代谢物（fecal glucocorticoid metabolites, FGMs）水平展开调查，这些种群受到来自自然与人为两类因子共同驱动的不同程度应激胁迫：自然因子包括捕食者存在情况、森林覆盖率、下层植被覆盖、有蹄类种群密度与气温；人为因子则涵盖狩猎收获量、建设用地占比与道路密度。研究结果显示，两类有蹄类在无大型食肉动物分布的区域中，其FGM浓度最高且变异程度最大；而在有狼与猞猁分布的区域，FGM水平则最低且变异程度最小。人为因子（狩猎收获量、道路与建设用地）与两类物种的FGM水平梯度呈显著正相关。马鹿与狍子种群内测得的FGM浓度均值与变异程度，均随狩猎收获量的波动呈正向变化，而随最低气温呈负向变化。狍子FGM的变异程度还会随建设用地占比的增加呈正向升高。研究结果表明，相较于以人类相关因子为主导的无食肉动物区域，大型食肉动物栖息区域内的野生有蹄类种群应激水平更低且变异程度更小。这一现象可通过猎物的进化适应机制得到解释：长期暴露于自然捕食风险中的猎物已演化出对应适应策略，却难以应对人类活动带来的风险——这或许是因为人类干扰强度极高且发生规律难以预测。