Grizzly Bear Refuge Report
Grizzly Bear Refuge – Updated January 23rd, 2014
Across the province female Black bears and Grizzly bears are beginning to produce litters of cubs. Late January and early February, female bears inside their hibernating dens will give birth between 1 to 4 cubs if they were successful in mating during late spring early summer, typically the months of June or July. Females have a unique reproductive feature known as delayed implantation. In late spring, male and female bears will seek each other for mating purposes and once mating is complete the female then harbors the fertilized eggs within her uterus. Those embryos free float in her uterus till late fall when the female has entered her winter den. A female bear’s body is dependent on the amount of fat she has been able to store in order to successfully have a litter of cubs. If the female has put enough body fat on to sustain her cubs and herself, those embryos will then attach to the uterine wall and the gestation period begins lasting only 8 weeks. In late January, early February those cubs will be born weighing only a few grams, they are blind and virtually hairless. The cubs stay with mom in the safety and warmth of the den, nursing and gaining weight from her very nutrient rich milk. When they emerge in late April, early May with mom, they will be about 5 to 8lbs with a full coat of fur and a very curious nature.
Delayed implantation is a unique survival feature to bears. This ensures that the female bear doesn’t starve inside the den while caring for her cubs. Black bears will keep their cubs for a full 2 years before sending them on their own. Female Grizzly bears keep their cubs for 3 sometimes 4 full years. Grizzly bears are one of the slowest reproducing of the 8 bear species in the world.
Nicole Gangnon Grizzly Bear Wildlife Ranger