North American Beaver

hazel beaver 1-7-15(Castor canadensis)

Habitat and Distribution: Found in streams and small lakes with nearby growths of willow, aspen, poplar, birch, or alder throughout Alaska, Canada, the United States, and northern Mexico.

Size: 34-46 inches long; 30-60 pounds (occasionally up to 80 pounds)

Wild Diet: Bark, twigs, cambium, leaves and roots of deciduous trees; aquatic plants

Predators: Primarily humans; sometimes wolves, bears, cougars, lynx, wolverines, and coyotes

Reproduction: Beavers are monogamous and mate for life. Females give birth to one litter per year, usually between April and June, after a 3-month gestation. Newborn kits are fully furred, have open eyes, and can swim within 24 hours. Both parents feed and protect the young. Kits are usually weaned within two weeks, but may stay with their parents for up to 2 years until they are ready to leave and construct their own homes.

Behavior: Beavers are known for their construction abilities, engineering complex lodges, dams and canals. Lodges are dome-shaped shelters of woven sticks and grass plastered with mud. The floors inside are carpeted with bark, grass, and wood chips. One or more underwater entrances provide escape from terrestrial predators. Dams slow the flow of water, creating ponds of still, deep water perfect for lodge construction. To harvest building materials, beavers work alone or in pairs to cut down trees with their teeth and then create canals to float tree sections back to the construction site. They may also use canals to float food back to the lodge if they find a good food source.


IUCN Status: Least Concern

Pollution and heavy hunting once put beaver populations in jeopardy, but re-introduction programs and habitat preservation have allowed them to recover. Beavers are still hunted for their fur, but this is well-regulated.

Did you know?

  • A single beaver can fell a tree with a 5 to 6 inch trunk in less than half an hour.
  • Beaver lodges are up to 36 feet wide at the base.
  • A beaver's front teeth are harder on the front than the back. As a result, the back wears down faster, creating a sharp edge for easy chewing.