Evidence for interspecific modulation of carcass consumption among facultative scavengers in Asian temperate forest

Abstract

Interspecific interactions are one of the key drivers that can determine community structure through the complex energy dynamics in food webs. Top-down regulation by large mammals on other species is well documented, but is still limited to a few species in scavenging communities that compete for limited and ephemeral animal carcasses. In this study, we examined the effects of large scavengers (Asian black bear, Ursus thibetanus and wild boar, Sus scrofa) and seasons (summer and autumn) on carrion consumption. Specifically, we analyzed how large scavenger and season affected the visitation and duration of feeding on carcasses by other omnivorous scavengers (both each other and smaller mesocarnivores) in a temperate forest ecosystem in Japan. We found that bears and wild boars appear to have a competitive relationship by limiting each other's visitation to the carcasses. We also found that these large scavengers had limiting effects on the carrion consumption by mesocarnivores, suggesting that large scavengers not only reduce the available carrion largely but also create a landscape of fear for mesocarnivores. In addition, we found that the potential probability of visitation for large scavengers was associated with season. This suggests that top-down regulation from large scavengers to mesocarnivores may change with season, especially in omnivorous communities in temperate regions with varying seasonal abundance of different food sources. These complex interspecific interactions between scavengers among different seasons can contribute to maintaining and structuring the food web in this system.