Cannibalism in Bears: A Review and Meta-Analyses

Emmarie P. Alexander, Maximilian L. Allen, Shinsuke Koike

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Common food of bears includes small ungulates, spawning fish, mast crops, berries, and insects. To forage optimally, bears must consume substantial quantities of food at one location to minimize the cost of energy expenditure. While rare for some species, bears may also scavenge and exploit large prey carcasses killed by other carnivores. Another less frequent strategy is cannibalism (defined as the killing and consumption of a conspecific). This foraging strategy is not thoroughly understood in bears, but it has been suggested that cannibalism generally allows animals to increase their fitness by removing a competitor and creating a food resource. We observed a 10-year-old female cannibal partially consuming a 3-year-old subadult during a study of Asiatic black bears (Ursus thibetanus) in Japan and wanted to understand the context of this infrequent foraging tactic. We performed a systematic literature review and meta-analysis of previous scientific literature. We considered five types of cannibalism: conspecific strife (the killing and consumption of adult competitors), infanticide (the killing and eating of dependent young by conspecifics), filicide (the killing and eating of dependent young by parents), siblicide (the killing and eating of siblings), and scavenging (the eating of a conspecific that is already dead). We found 33 articles that documented 172 accounts of cannibalism among four species: American Black Bear (Ursus americanus), Asiatic Black Bear, Brown Bear (Ursus arctos), and Polar Bear (Ursus maritimus). The most documented type of cannibalism across species was infanticide (55 incidents), with filicide being the least documented (9 incidents). Cannibalism incidents occurred most in polar bears, whereas incidents were less documented in Asiatic black bears. These findings suggest that frequencies and patterns of cannibalism vary within the genus; thus, characterizing the species differences may allow for identifying how bears alter their diet in response to change in prey availability to forage optimally.
Original languageEnglish (US)
Title of host publication81st Midwest Fish and Wildlife Conference
StatePublished - 2021


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