Observations of Intraspecific Aggression and Cannibalism in Polar Bears (<i>Ursus maritimus</i>)

Cannibalism in polar bears appears to occur as carrion feeding and as attacks by males on small cubs or incapacitated individuals. Direct observations indicate that intraspecific killing and cannibalism occur among polar bears throughout the Arctic. The high incidence of Trichinella infection and circumpolar observations of cannibalism suggest that polar bears will readily eat other polar bears when they can do so without excessive risk of injury. Speculations that intraspecific aggression and cannibalism may be an important social and ecological force are consistent with existing information on polar bear biology. Key words: aggression, cannibalism, parasitism, polar bears, population dynamics, Trichinella , Ursidae , Ursus maritimus