A female in oestrus gives off a characteristic scent which is quickly picked up by male bears in the area who then follow her trail. Both males and females are polygamous and a pair remains together for only a short period.
Males are highly competitive over females and large bears often drive smaller ones away.
Between evenly matched bears, fierce fighting sometimes breaks out, leaving bears battered and scarred. Thus, although the gestation period is 7 to 8 months, fetal development takes place only during the last 6 to 8 weeks. Black bear cubs are born in January or February while the female is still in the den. Usually two are born, but some litters contain only one, or as many as four cubs. Their hindquarters are under-developed, but they move around, never far from their mother, by crawling and pulling themselves with their front legs.