Hair Growth of Brown Bears during Winter

To examine whether hair of brown bears (Ursus arctos) grows during winter, we shaved off the hair (guard hair and underfur) from an area 5 cm in diameter on back region of eight brown bears before winter, and observed the shaved area the following spring. As a result, we found that underfur had grown in the shaved areas on all individuals. Unlike Asiatic black bear (Ursus thibetanus), which does not show hair growth during winter, the underfur could be necessary for brown bear inhabiting in sub-arctic region during winter. Maintaining actively the hair cycle in brown bear may be an adaptation to colder environments.