North American Beavers

illustration of a beaver chewing a log, dam in background

The North American Beaver

The North American Beaver (Castor Canadensis)

The beaver is the largest rodent in North America. An adult usually weighs from 11-32 kg (24-72 lbs.) and her body length without the tail is around 74-90 cm (29-35 in).

The beaver’s life style is semi aquatic with its thick layer of fat, large flat paddle-shaped tail, large webbed feet and a special eye membrane that helps her see under water. The beavers “double coat” made up of oily long coarse outer hairs and short fine inner hairs also helps a beaver stay warm while in the water.

Beavers are active mainly at night. They are excellent swimmers and may remain submerged for up to 15 minutes.

A beaver will use sticks, twigs, rocks and mud to build a “dam” that will stretch the full length of a river to create an artificial pond where they can build their protective lodge. The beaver piles stick and nearby trees across the river and then eats out underwater entries and exits and constructs two platforms within the stick structure. When winter arrives, beavers will place mud over the stick lodge to keep it insulated from the cold. The inner bark, twigs, shoots and leaves selected for the lodge provide an important part of the beaver’s diet in addition to providing warmth and protection.

The largest beaver dam was discovered in northern Alberta’s Wood National Park in 2007. This massive structure is 2,790 ft. in length and twice the size of the Hoover Dam.