Data from: Why do top predators engage in superpredation? From an empirical scenario to a theoretical framework

Lethal interactions can shape ecosystem structure, and consequently understanding their causes is ecologically relevant. To improve both empirical and theoretical knowledge on superpredation (i.e. predation on high-order predators), we studied an eagle owl population, including its main prey and mesopredators, and then we crossed these results with existing theories to provide a reasoning framework. We fitted our field data into four main causes explaining lethal interactions: food stress, opportunistic superpredation, removal of a competitor, and removal of a potential threat. Empirically, superpredation seemed to be mostly determined by the combination of the food-stress and opportunistic-superpredation hypotheses, which highlights the complexity of the factors triggering superpredation. Therefore, besides being a response to lower food availability, superpredation may also represent an effective mechanism to remove potential predators and/or competitors, either intentionally or not. Our theoretical framework focused on the decision-making process in superpredation, considering four inter-related stages: encountering; attacking; and capturing a mesopredator; as well as consuming a mesopredator once killed. Superpredation almost certainly results from a complex process of decision-making, accounting for costs and benefits assessed moment-to-moment and for each mesopredator individual. It is time to build bridges between theoretical and empirical studies to further understand the mechanisms driving complex interactions among top predators and mesopredators.

致死性相互作用可塑造生态系统结构，因此厘清其成因具有重要的生态学意义。为深化针对超捕食（superpredation，即对高阶捕食者的捕食行为）的实证与理论认知，本研究以某雕鸮种群为研究对象，涵盖其主要猎物与中型捕食者（mesopredator），并将实地观测结果与现有理论相结合，构建了一套推理框架。我们将实地观测数据归纳为四类可解释致死性相互作用的核心成因：食物胁迫、机会主义型超捕食、竞争者清除以及潜在威胁清除。从实证层面来看，超捕食行为主要受食物胁迫假说与机会主义超捕食假说的共同驱动，这一结果凸显了触发超捕食行为的各类因素的复杂性。因此，超捕食行为除可作为食物资源匮乏的应对策略之外，还可能成为一种有意或无意清除潜在捕食者与/或竞争者的有效手段。本研究的理论框架聚焦于超捕食行为中的决策过程，涵盖四个相互关联的阶段：偶遇中型捕食者、发起攻击、捕获中型捕食者，以及成功击杀后取食该猎物。超捕食行为几乎必然源于一套复杂的决策过程，需时刻评估针对每一个中型捕食者个体的成本与收益。如今，我们亟需搭建理论研究与实证研究之间的桥梁，以进一步厘清顶级捕食者与中型捕食者之间复杂相互作用的驱动机制。