Abstract 133 – The role of Asiatic black bears as a scavenger in a Japanese temperate forest

Akino Inagaki, Maximilian L. Allen, Kahoko Tochigi, Tetsuya Maruyama, Shinsuke
Koike

Animal carcasses are an ephemeral but nutritionally rich resource. Large carcasses attract
various vertebrate scavengers, and the interactions among scavenger species on or around
carcasses can influence the composition of the scavenger guild and its ecological functions (e.g.,
carrion consumption rates). Dominant scavengers, including American black bears (Ursus
americanus) and brown bears (U. arctos), usurp prey from predators and monopolize carcasses.
Despite Asiatic black bears (U. thibetanus) are one of the most frequent scavengers of sika deer
(Cervus nippon) carcasses in the temperate forests of Japan, their scavenging behavior remains
poorly understood. The aim of this study was to investigate the effect of Asiatic black bear
presence and seasonal variation (summer and autumn) on carrion consumption —specifically,
the number of visits and duration of feeding on deer carcasses— by other omnivorous
scavengers (wild boars [Sus scrofa], raccoon dogs [Nyctereutes procyonoides], red foxes [Vulpes
vulpes], and Japanese martens [Martes melampus]). We found that Asiatic black bears had
limiting effects on carrion consumption by all other scavengers, suggesting that bears create a
landscape of fear among scavengers as well as diminish available carrion largely. Additionally,
the potential probability for carcass visitation of bears decreased from summer to autumn,
suggesting a shift in carcass preference as bears transition their primary food source to acorns.
This shift may alter the magnitude of the limiting effect exerted by bears on other scavengers
according to seasonal variations. We highlight the importance of Asiatic black bears' role in
structuring the scavenger guild in this system.