Data from: Large carnivores avoid humans while prioritizing prey acquisition in anthropogenic areas

Large carnivores are recovering in many landscapes where the human footprint is simultaneously growing. When carnivores encounter humans, the way they behave often changes, which may subsequently influence how they affect their prey. However, little research investigates the behavioral mechanisms underpinning carnivore response to humans. As a result, it is not clear how predator-prey interactions and their associated ecosystem processes will play out in the human-dominated areas into which carnivore populations are increasingly expanding. We hypothesized that humans would reduce predation risk for prey by disturbing carnivores or threatening their survival. Alternatively, or additionally, we hypothesized that humans would increase predation risk by providing forage resources that congregate herbivorous prey in predictable places and times. Using gray wolves (Canis lupus) in Jackson Hole, Wyoming, USA as a study species, we investigated 170 kill sites across a spectrum of human influences ranging from heavily restricted human activities on protected federal lands to largely unregulated activities on private lands. Then, we used conditional logistic regression to quantify how the probability of predation changed across varied types and amounts of human influences, while controlling for environmental characteristics and prey availability. Wolves primarily made kills in environmental terrain traps and where prey availability was high, but predation risk was significantly better explained with the inclusion of human influences than by environmental characteristics alone. Different human influences had different, and even converse, effects on the risk of wolf predation. For example, where prey were readily available, wolves preferentially killed animals far from motorized roads but close to unpaved trails. However, wolves responded less strongly to humans, if at all, where prey were scarce, suggesting they prioritized acquiring prey over avoiding human interactions. Overall, our work reveals that the effects of large carnivores on prey populations can vary considerably among different types of human influences, yet carnivores may not appreciably alter predatory behavior in response to humans if prey are difficult to obtain. These results shed new light on the drivers of large carnivore behavior in anthropogenic areas while improving understanding of predator-prey dynamics in and around the wildland-urban interface.

在诸多人类活动足迹同步扩张的自然景观中，大型食肉动物的种群正逐步恢复。当食肉动物与人类遭遇时，其行为模式通常会发生改变，这进而可能影响它们对猎物的作用效果。然而，目前针对食肉动物应对人类的行为机制的研究仍较为匮乏。因此，在食肉动物种群日益扩张的人类主导区域内，捕食者-猎物相互作用及其相关的生态系统过程将如何发展，目前尚不明确。我们提出如下假说：人类可通过干扰食肉动物或威胁其生存，降低猎物面临的捕食风险。或者，我们也提出另一项补充假说：人类可通过提供饲草资源，使植食性猎物在可预测的时间与地点聚集，从而提升猎物面临的捕食风险。本研究以美国怀俄明州杰克逊霍尔的灰狼（Canis lupus）为研究对象，对170处猎物捕杀位点展开调查，这些位点覆盖了从受保护联邦土地上严格受限的人类活动，到私人土地上基本无管制的人类活动的全梯度人类影响范围。随后，本研究采用条件logistic回归（conditional logistic regression）方法，量化分析捕食发生概率如何随不同类型与强度的人类影响发生变化，同时控制环境特征与猎物可获得性的干扰。灰狼主要在具有地形陷阱特征的区域以及猎物可获得性较高的地点实施捕杀，但纳入人类影响因素后，对捕食风险的解释度显著高于仅使用环境特征的模型。不同类型的人类影响对灰狼捕食风险的影响存在差异，甚至截然相反。例如，在猎物易于获取的区域，灰狼优先捕杀距离机动车道较远、但靠近非铺装步道的猎物。但在猎物匮乏的区域，灰狼对人类的响应程度显著减弱（若确实存在响应的话），这表明灰狼会优先获取猎物，而非规避与人类的互动。总体而言，本研究表明，大型食肉动物对猎种种群的影响会因人类影响类型的不同而存在显著差异，但如果猎物难以获取，食肉动物可能不会因人类的存在而明显改变其捕食行为。本研究结果不仅阐明了人为活动区域内大型食肉动物行为的驱动因素，还加深了人们对城乡交错带（wildland-urban interface）内外捕食者-猎物动态关系的认识。