Data from: Kleptoparasitism and scavenging can stabilize ecosystem dynamics

Scavenging is ubiquitous in nature and yet its implications for ecosystem dynamics have rarely been investigated. We used camera traps on wolf kills to investigate the role of scavenging on predator and multi-prey dynamics in a Northern Apennine system (Italy). In contrast to North American systems, throughout much of Eurasia, the omnivorous wild boar (Sus scrofa) successfully competes with wolves (Canis lupus) for the meat of their kills. We developed a deterministic multi-trophic web model (wolf, vegetation and two prey species, deer and wild boar), tunable through a parameter that governs the impact of prey-sharing between wolves and wild boar. When prey-sharing is absent or scarce, populations oscillate, but above a threshold value the trophic web is stabilized, with the regime solution becoming a fixed stable point. Both deer and wild boar then increase as a function of prey-sharing, and the impact of herbivores on the vegetation increases. When prey-sharing exceeds another threshold, however, the system collapses due to the extinction of both wolves and wild boar, but not of deer. Our analysis shows that scavenging is crucial for the dynamics of this ecosystem and thus, in general, it should not be overlooked in food web modelling. The exploitation of wolf kills by wild boar may allow juveniles and yearlings to obtain high quality resources that are not usually available, helping the omnivorous wild boar to compensate for losses caused by heavy hunting. This is likely to make them even more invasive and difficult to control.

食腐行为在自然界中普遍存在，但其对生态系统动态的影响却鲜有研究。我们通过在灰狼（Canis lupus）的猎物尸体上布设红外相机陷阱，探究了食腐行为在意大利北亚平宁山脉生态系统中对捕食者与多种猎物种群动态的调控作用。与北美生态系统不同，在欧亚大陆大部分区域，杂食性野猪（Sus scrofa）能够成功与灰狼争夺其猎杀的猎物尸体。我们构建了一个确定性多营养级食物网模型，涵盖灰狼、植被以及两种猎物（鹿与野猪），可通过一个调控狼与野猪间猎物共享强度的参数进行调节。当猎物共享程度极低或不存在时，各物种种群会呈现周期性波动；而当共享程度超过某一阈值后，食物网将趋于稳定，系统解收敛为固定稳定点。随着猎物共享程度提升，鹿与野猪的种群数量均会增长，同时草食动物对植被的影响也随之增强。但若猎物共享程度超过另一阈值，系统则会崩溃——灰狼与野猪均会灭绝，但鹿种群得以存续。本研究分析表明，食腐行为对该生态系统的动态至关重要，因此总体而言，在食物网建模中不应忽视食腐过程的作用。野猪利用灰狼猎杀的猎物尸体，可使其幼崽与1龄个体获取通常难以获得的优质食物资源，从而帮助杂食性野猪种群弥补高强度狩猎带来的种群损失。这可能会进一步加剧野猪的入侵性，使其更难被有效防控。