Data from: Fatal attraction? Intraguild facilitation and suppression among predators

Competition and suppression are recognized as dominant forces that structure predator communities. Facilitation via carrion provisioning, however, is a ubiquitous interaction among predators that could offset the strength of suppression. Understanding the relative importance of these positive and negative interactions is necessary to anticipate community-wide responses to apex predator declines and recoveries worldwide. Using state-sponsored wolf (Canis lupus) control in Alaska as a quasi-experiment, we conducted snow track surveys of apex, meso-, and small predators to test for evidence of carnivore cascades (e.g., mesopredator release). We analyzed survey data using an integrative occupancy and structural equation modeling framework to quantify the strengths of hypothesized interaction pathways, and we evaluated fine-scale spatiotemporal responses of non-apex predators to wolf activity clusters identified from radio-collar data. Contrary to the carnivore cascade hypothesis, both meso- and small predator occupancy patterns indicated guild-wide, negative responses of non-apex predators to wolf abundance variations at the landscape scale. At the local scale, however, we observed a near guild-wide, positive response of non-apex predators to localized wolf activity. Local-scale association with apex predators due to scavenging could lead to landscape patterns of mesopredator suppression, suggesting a key link between occupancy patterns and the structure of predator communities at different spatial scales.竞争与压制被认为是塑造食肉动物群落结构的核心驱动力。然而，通过腐尸资源供给实现的促进作用，却是食肉动物间普遍存在的互作类型，可抵消压制作用的强度。明确这两类正负互作的相对重要性，是预测全球范围内顶级食肉动物种群衰减与恢复所引发的群落尺度响应的必要前提。本研究以阿拉斯加官方主导的灰狼（Canis lupus）防控项目作为半自然实验，通过对顶级、中型及小型食肉动物开展雪迹调查，以验证食肉动物级联效应（如中型捕食者释放（mesopredator release））的存在证据。本研究采用整合占用模型与结构方程模型的联合分析框架解析调查数据，量化各假设互作通路的强度；同时基于无线电项圈监测数据识别的灰狼活动集群，评估非顶级食肉动物的精细尺度时空响应模式。与食肉动物级联效应假说相悖的是，在景观尺度下，中型与小型食肉动物的占用模式均显示，非顶级食肉动物类群整体对灰狼种群丰度变化呈现负向响应。但在局地尺度上，非顶级食肉动物类群整体对局部灰狼活动则呈现近乎全域的正向响应。由于食腐行为带来的与顶级捕食者的局地关联，可能会催生中型捕食者受压制的景观尺度格局，这表明不同空间尺度下的占用模式与食肉动物群落结构之间存在关键关联。