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.