Shiratsuru Shotaro, Karasov William H, Pauli Jonathan N
Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, WI, USA.
Oecologia. 2025 Sep 22;207(10):162. doi: 10.1007/s00442-025-05797-y.
Energy acquisition and risk avoidance can drive prey activity, but mechanistic understanding of the process through which prey traits mediate this energy-safety trade-off is lacking. We analyzed daily activity in winter of two winter-adapted prey that differ in antipredator strategies and physiological constraints on activity: snowshoe hares (Lepus americanus) and North American porcupines (Erethizon dorsatum). First, we constructed an energetics-based model to predict daily activity time for each species based on temperature and corresponding mass-dependent thermoregulatory costs. We then examined what factors drove the deviations of observed activity from the model prediction based on energy balance, considering individual variation. Neither hares nor porcupines achieved energy balance when temperatures fell below the thermoneutral zone. Activity deviations of hares from energy balance were explained by environmental factors associated with risk and energetics, with nominal individual variation being exhibited. In contrast, activity deviations of porcupines were independent of the environmental factors, and porcupines exhibited pronounced individual variation in activity. Our findings highlight that antipredator strategies and physiological constraints on activity can mediate the behavioral energy-safety trade-off of prey. Notably, morphological protection and energy reserves facilitate behavioral flexibility by relaxing the energy-safety trade-off, whereas dependence on behavioral predator avoidance limits the behavioral flexibility of prey.
能量获取和风险规避会驱动猎物的活动，但目前缺乏对猎物特征介导这种能量 - 安全权衡过程的机制性理解。我们分析了两种适应冬季的猎物在冬季的日常活动，这两种猎物在反捕食策略和活动的生理限制方面存在差异：雪鞋兔（美洲兔）和北美豪猪（帚尾豪猪）。首先，我们构建了一个基于能量学的模型，根据温度和相应的质量依赖性体温调节成本来预测每个物种的每日活动时间。然后，我们基于能量平衡，考虑个体差异，研究了哪些因素导致观察到的活动偏离模型预测。当温度降至热中性区以下时，野兔和豪猪都无法实现能量平衡。野兔活动偏离能量平衡的情况可以由与风险和能量学相关的环境因素来解释，个体差异不明显。相比之下，豪猪的活动偏离与环境因素无关，豪猪在活动中表现出明显的个体差异。我们的研究结果表明，反捕食策略和活动的生理限制可以介导猎物的行为能量 - 安全权衡。值得注意的是，形态保护和能量储备通过放宽能量 - 安全权衡促进了行为灵活性，而对行为性避敌的依赖则限制了猎物的行为灵活性。
