| Summary: | application/pdf 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. ヒグマの体毛（保護毛および下毛）が冬期に成長するか否かを検証するため，秋期に8頭の飼育個体の背部を直径約5cmのサークル状に剃毛し，翌春その部位の観察を行った。その結果，ヒマラヤグマでは冬期に体毛は成長しないとされているが，ヒグマでは下毛の成長が認められ，亜寒帯域に生息する本種にとって下毛の存在は重要であることが示された。ヒグマにおける冬期の毛周期活性の維持は寒冷に対する適応であるかもしれない。 departmental bulletin paper
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