Do prey recognise the varying risk of lion predation?

Predators can induce behavioural changes in prey that influence vigilance, grouping patterns and space use, and these can ultimately affect prey demography and trophic interactions. Consequently, prey must respond to the risk of predation, but little is known about the features that drive the spatial responses of prey species to predators. We tested whether prey rely more heavily on olfaction or vision in determining their proximity to lions reintroduced to Addo Elephant National Park, South Africa. We also tested whether prey that are preferentially killed by lions show greater responsiveness than those that are not, and whether prey respond to predator behavioural states and hunger. Over 1588 observations of potential prey locations in relation to lions under varying wind directions, lion behaviours and hunger states throughout the day and night, we found that vision is the primary determinant of risk avoidance with no evidence of wind-driven odour responses affecting prey proximity. Prey outside the preferred prey weight range of lions occurred closer to lions than those species most at risk of lion predation. Prey were more likely to be closer to covertly behaving lions and further from stationary lions. Our evidence suggests prey responses to predators in intact, multi-species assemblages are context dependent, but driven largely by vision.

捕食者可诱发猎物产生行为改变，进而影响其警戒行为、集群模式与空间利用策略，最终可对猎物种群动态及营养级相互作用造成影响。鉴于此，猎物必须应对捕食风险，但当前学界对驱动猎物种群针对捕食者产生空间响应的关键特征仍缺乏深入认知。本研究以重新引入至南非阿多大象国家公园（Addo Elephant National Park）的狮子为研究对象，检验了猎物在判定自身与狮子的空间距离时，是否更依赖嗅觉还是视觉。我们还开展了两项对照检验：一是被狮子优先捕食的猎物是否相较于非优先捕食对象表现出更强的响应性；二是猎物是否会对捕食者的行为状态与饥饿状态做出响应。在覆盖昼夜全时段、涵盖不同风向、狮子行为模式与饥饿状态的野外观测中，我们累计开展了超过1588次关于潜在猎物位置与狮子相对空间关系的观测。结果显示，视觉是猎物风险规避行为的核心决定因素，未发现风介导的嗅觉响应会影响猎物与狮子的空间距离的证据。处于狮子偏好捕食体重区间外的猎物，相较于最易遭受狮子捕食的物种，距狮子的平均距离更近。猎物更倾向于靠近处于隐秘活动状态的狮子，而远离静止状态的狮子。本研究结果表明，在完整的多物种种群组合中，猎物对捕食者的响应具有情境依赖性，但整体上主要由视觉主导。