North American Bear Program (sample photographs and notes)
All North American bears descended from Etruscan bear stock in Asia.
First to arrive in North America 2.5 million years ago was the black bear.
Brown bears made their way to North America 300,000 years ago by way of the Aleutian land bridge.
DNA evidence confirms the polar bear evolved from the brown bear 150,000 years ago.
There are grizzly bear hybrids, where a polar bear and grizzly have produced offspring.
In North America there are an estimated 750,000 black bears, 60,000 brown bears and 25,000 polar bears.
Read More First to arrive in North America 2.5 million years ago was the black bear.
Brown bears made their way to North America 300,000 years ago by way of the Aleutian land bridge.
DNA evidence confirms the polar bear evolved from the brown bear 150,000 years ago.
There are grizzly bear hybrids, where a polar bear and grizzly have produced offspring.
In North America there are an estimated 750,000 black bears, 60,000 brown bears and 25,000 polar bears.
Brown Bear (Grizzly)
The number of cubs in a brown bear litter depends upon the female's body fat content and other factors. They usually have one to three cubs, but can have up to five. Usually the cubs remain with the mother for two and a half years. They weigh between 10-15 pounds when they leave the den. Having four or more cubs strains the milk production of the mother. Some times one cub will not suckle enough and the mother will stop lactating. The upper teats produce the most milk and the dominate cubs get the most productive teats. Teat position is determined very early in the den.
