Mating season: Late May through June in northeastern Minnesota but into August in eastern and southern states. Males are ready to mate throughout that period but each female is ready for only a few days.
Implantation: Eggs are fertilized at the time of mating but wait until November to implant in the wall of the uterus and begin development.
Birth dates: Usually mid to late January in most areas. January-February in southeastern states.
Litter size: Typically 2 in western North America and 3 in eastern North America. First litters are often 1 or 2 cubs. Record: 6 cubs in Pennsylvania.
Birth Weight: Usually less than a pound. Bear cubs are the smaller at birth, compared to mother weight, of any placental mammal.
Parental Care: Offspring stay with their mothers for 16-17 months (or rarely an extra year) and may stay in her territory for several more years.
Sex Ratio: 50:50 at birth.
Sex Ratio at Maturity: 1 male per 2-5 females. Young males are more likely to die from human-related causes than are young females because subadult males leave their mothers’ territories and often travel through residential areas.