The Cubs Develop
By the end of February, cubs are 4 to 6 weeks old and usually weigh 2-3 pounds. They have dense fur almost an inch long. They can thermo-regulate to some extent, but they still cry for help staying warm and fed. They can crawl, but they can’t walk. Their eyes are opening or fully open.
On warmer days, with temperatures in the 20’s, the cubs often sleep partially exposed on their mother’s back.
Mother loses .36 to .61 pounds a day converting fat, water, and other body stores to milk and energy. She may eat snow around the den entrance.
In March, the cubs’ fur grows to over an inch. Temperatures are rising. The cubs are walking in the den on warmer days. Melting snow drips on the cubs or soaks the bedding. Mothers lick the cubs dry.
By early April, most cubs weigh 3-9 pounds, depending upon the mothers’ weight and how many littermates competed for her milk. The denning period is over or almost over.
This video shows a wild black bear mother caring for her three 5-week-old cubs. They are snug in their dug den as snow gently falls outside. The mother is 6-year-old June and this is her 2nd litter. The light-faced cub is a female (Lily) and the other 2 are males (Cal and Bud). This exceptionally trusting mother allowed us to place a video camera in her den to obtain these intimate scenes of bear family life.