Bear & Cubs Black Ink Heather

Bear and Cubs

Black bears are typically solitary creatures, except for family (a female with cubs) groups and during mating season, which peaks in May and June. Following fertilization, the embryo doesn’t implant in the uterus until fall, at the time of den entrance. This process of delayed implantation occurs in all bear species and allows the female bear’s body to physiologically “assess” her condition before implantation occurs and the period of gestation leading to the birth of cubs really begins. Delayed implantation allows the female to not waste fat reserves and energy in sustaining a pregnancy that would have little chance of success because her condition is too poor. Females give birth to cubs every other year if food sources are sufficiently plentiful. In years when food supplies are scarce, a female may skip an additional year or two between litters. The cubs are born in the mother’s winter den, and will den with her again the following winter. The following spring, when the cubs are one and a half years old, the cubs and female will separate and the female will breed again. A black bear litter can have one to five cubs, but most commonly litters contain two cubs. Black bears can live up to 30 years in the wild, but most die before they are in their early 20s.

Credit National Wildlife Federation