Abstract
Sexual behavior of the Hokkaido brown bears in captivity was observed during the breeding sea-sons in 1982 and 1983. Pairing between the males and females was found to be random and occurred most frequently at around 7 AM and again 7 PM. Chance of pairing peaked at the beginning of June during the breeding season. Copulation took place in the sequence of mounting, pelvic thrusting, quivering and dismounting, and average copulation time was 23 minutes. Ejaculation was suspected to have occurred during quivering. Females in heat were observed to be receptive to the males for a long period during the breeding season. Estimated durations of estrus varied widely between animals. A decrease in mounting frequency with age was observed in the males but the receptivity of the females was not influenced by age.
