Scavenging on a Carcass of Sika Deer by Introduced Raccoon Dogs (Nyctereutes procyonoides) in Spring: A Case Report in the World Heritage Site of Yakushima Island, Japan

Abstract. Understanding the behavior and ecology of non-native species is important to assess their impact on food webs and ecosystem functions and to facilitate the management of non-native species. The present study reports a case of scavenging on a deer carcass by mammals, especially introduced raccoon dogs and native Japanese weasels, in the World Heritage Site of Yakushima, Japan. A sensor camera was placed near the carcass from March to May 2022 to record scavenging behavior of mammals. Out of at least six species of mammals filmed, raccoon dogs and weasels fed on the carcass. Raccoon dogs almost monopolized the carcass, i.e., raccoon dogs were filmed around carrion more frequently and spent more time scavenging than weasels. Raccoon dogs and weasels were filmed around the carcass at similar times in a day, and no overt aggression was observed between the two species, but weasels were displaced by raccoon dogs. Japanese macaques and sika deer avoided and never fed on carrion. The present study suggests that raccoon dogs contribute to carrion decomposition in the World Heritage Site of Yakushima and that comprehensive studies of carrion availability and the scavenger community could help promote the management of introduced raccoon dogs in Yakushima.