Beyond Carnivory: Herbivores as Carrion Visitors

Wildlife carcasses represent important ephemeral resource pulses that can influence a variety of scavenging organisms, from microbes to insects and vertebrate scavengers. Typical vertebrate scavengers are either carnivore or omnivore species, while herbivore species are generally not considered as carrion consumers in the strict sense. However, some studies have recorded herbivores feeding on bones for mineral intake, a behavior known as osteophagia. At the same time, carcasses may represent local risk sites for herbivores as they attract scavenging generalist predators and may also be associated with pathogen and parasite exposure. To test whether carrion acts primarily as a repellent (H1) or as an attractive resource (H2) for herbivores, we used camera-trap data from 158 experimentally exposed carcasses and 69 control sites in nine national parks across Germany. We quantified mammalian herbivore and carnivore visitation frequencies at carcass and control sites and assessed seasonal effects and spatial variation. Overall, herbivores showed significantly lower visitation frequencies at carcass sites compared to controls. This avoidance was strongly seasonal: herbivore visitation did not differ between carcass and control sites in winter but was substantially lower at carcass sites in summer. In contrast, carnivore visitation frequencies were significantly higher at carcass sites than at controls, and, also higher in winter compared to summer. Although visitation frequencies varied among national parks, the effect of carcass presence did not differ significantly among parks. Despite observations of occasional interactions with carrion by herbivores in our and other studies, the results overall support the hypothesis of carrion acting primarily as a localized repellent for vertebrate herbivores rather than as an attractive nutritional resource. However, the mechanism underlying this avoidance remains unsolved and may reflect perceived predation risk, scavenger activity, pathogen and parasite avoidance, human disturbance, or other carcass-associated cues.