Data from: Fear and lethality in snowshoe hares: the deadly effects of non-consumptive predation risk

Predators play a critical, top-down role in shaping ecosystems, driving prey population and community dynamics. Traditionally, studies of predator-prey interactions have focused on direct effects of predators, namely the killing of prey. More recently, the non-consumptive effects of predation risk are being appreciated; e.g., the Ecology of Fear. Prey responses to predation risk can be morphological, behavioural, and physiological, and are assumed to come at a cost to prey fitness. However, few studies have examined the relationship between predation risk and survival in wild animals. We tested the hypothesis that predation risk itself could reduce survival in wild-caught snowshoe hares. We exposed female snowshoe hares to a simulated predator (a trained dog) during gestation only, and measured adult survival and, in surviving females, their ability to successfully wean offspring. We show for the first time in a wild mammal that the risk of predation can itself be lethal. Predation risk reduced adult female survival by 30%, and had trans-generational effects, reducing offspring survival to weaning by over 85% - even though the period of risk ended at birth. As a consequence of these effects the predator-exposed group experienced a decrease in number, while the control group substantially increased. Challenges remain in determining the importance of risk-induced mortality in natural field settings; however, our findings show that non-lethal predator encounters can influence survival of both adults and offspring. Future work is needed to test these effects in free-living animals.捕食者在生态系统塑造中扮演着关键的自上而下调控角色，驱动猎物种群与群落动态变化。传统而言，捕食者-猎物相互作用研究多聚焦于捕食者的直接效应，即捕食猎物的行为本身。近年来，捕食风险带来的非消耗性效应逐渐获得学界认可，例如恐惧生态学（Ecology of Fear）。猎物对捕食风险的响应可体现为形态、行为与生理层面，且这类响应通常会对猎物的适合度产生适应性代价。然而，目前针对野生动物捕食风险与存活率之间关联的研究仍较为稀缺。我们验证了如下假说：捕食风险本身即可降低野生动物的存活率。本研究仅在妊娠期对野外捕获的雌性雪兔施加了模拟捕食者刺激（经训练的犬只），并监测了成年个体的存活率，以及存活雌性个体成功抚育后代至断奶的能力。我们在野生哺乳动物中首次证实，捕食风险本身即可具备致死性。捕食风险使成年雌性雪兔的存活率下降30%，同时还产生了跨代效应：即便风险刺激在产仔后即终止，后代断奶前的存活率仍下降了85%以上。受上述效应影响，捕食者暴露组的种群数量出现下降，而对照组种群数量则显著增长。尽管目前仍存在研究挑战，难以量化风险诱导死亡在自然野外环境中的重要性，但我们的研究结果表明，非致命的捕食者遭遇可同时影响成年个体与后代的存活率。未来仍需开展相关研究，在自由活动的野生动物群体中验证此类效应。