A grizzly bear cub might be getting one of the richest mother’s milk, if not the richest. As soon as the cubs are born, looking very little like the cubs we may see six months later when then pop out of the den with their mother leading. The little cub is a fraction of their mom’s weight when born, less than one percent of their mother’s weight. The cubs weight about half a pound when born. Comparing that to us humans, the average baby is about seven percent of their mom’s weight. So, it’s important that the cubs have access to this rich milk to get ready when they pop out of the den six months later. Even though the calendar says spring, as many of you know, in the mountains we can be dealing with winter like weather in May and early June. Come to think of it. We can be dealing with winter anytime of the year in the Canadian Rockies.
A mother bear has six nipples. The two nipples closest to the pelvis get used first and as the cubs grow, they nurse from the top four. The mother bear may stop the milk production in the bottom two nipples. While in the den, the grizzly is using up all the fat she put on before denning to help produce the milk her cubs need. When the mother grizzly exits the den with her cubs, it is important for her to find food so she can continue producing milk during the approaching peak lactation period, June and July. Each one of the cubs during this time will end up consuming just under 1.5 liters of milk per day. As the cub grows, mother’s milk plays a smaller role in its overall diet, but one role never gets less important. The bond the mother forms with her cub when nursing.
