| Summary: | The growth, sexual dimorphism, and geographical variation in skulls of 596 brown bears (Ursus arctos) hunted in Hokkaido, Japan from 1971 to 1986 were investigated. Most cranial traits continued to increase after the age of sexual maturity, and in particular skulls became progressively wider with age. Skulls of males, even those of cubs and yearlings, were larger than those of females, and the difference became significant after two years of age. Skull dimensions tended to increase from south to north, in Hokkaido, and bears from the north-eastern region possessed higher brain cases and longer mandibles relative to skull length and width, than those in the southern region.
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