Observation of sexual behavior of captive Japanese black bears, Ursus tibetanus japonicus

摘要

Sexual behavior of 22 male and 17 female Japanese black bears, Ursus thibetanus japonicus, in Ani Bear Park was observed for 40 days from June 22 to July 31, 1996. The mating season in this bear park extended, from mid-June to early August. Their mating pattern was regarded as promiscuous type. The mating period of females varied from 12 to 35 days widely among animals. The mating period contained estrous and non-estrous period, which occurred irregulaly. Male mating behavior was suspected to accompany female estrus. Total mating days of male bears aged 4-5 years old were less than those of older males. In males over 6 years old, males weighed over 80kg had more total mating days than smaller males. These suggest that, under captive conditions with high density, some subordinate males, even if they had been matured, were probably unable to have opportunity to breed, due to Social hierachy related to the age and body weight of male Japanese black bears.