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Can malnourished black bears reproduce?

can_malnourished_reproduce.jpg Malnourished black bear females do not successfully reproduce. Their offspring are absorbed in utero, are stillborn, or starve from lack of milk.

In northeastern Minnesota, black bear females reproduce best if they weigh over 176 pounds in the fall. Twenty-eight (93%) of 30 pregnant females weighing over 176 pounds produced surviving cubs, but 16 weighing less than 148 pounds produced no cubs. Of 8 weighing between 148 and 176, only 4 produced cubs, and 43% of their cubs died.

The usual interval between litters is 2 years. But when natural foods are scarce, it sometimes takes 3 or 4 years for mothers to build up enough body reserves to produce the next litter.