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American Beaver

Castor canadensis [kas' tor kan uh den' sis]

American Beaver


The beaver is the second largest rodent, exceeded in size only by the capybara. It is up to 3 feet long, including 1 foot of broad scaly tail, and may weigh between 30 and 75 pounds. Its muzzle is blunt, ears small, and it has five toes on each foot. The toes on the front feet are strongly clawed and used for digging, manipulating food and carrying. The hind feet are webbed, with two split claws for grooming the fur and spreading waterproofing oil.

front and hind feet of the American Beaver

Distribution and Habitat

The American beaver ranges throughout all of North America except for the northern regions of Canada and the deserts of the southern United States and Mexico.


Beavers live in loose colonies, each made up of a set of parents and their offspring. Their home may be in a burrow in a bank, with an underwater entrance, or in a lodge in a "beaver pond," a pool made by damming a stream or river until it overflows. The lodge is built of sticks and mud, often against a clump of young trees, with underwater entrances, a central chamber which is above water level, and a ventilating chimney connecting the chamber with the top of the lodge. The central chamber may measure 8 feet wide and up to 3 feet high.

a typical beaver lodge

Beaver families are territorial and defend against other families.

Beavers are primarily nocturnal.


Beavers eat bark, mainly of aspen, maple, poplar, beech, birch, alder and willow, from the smaller branches cut when building the dam and lodge. They also eat water vegetation, as well as buds and roots. Twigs and branches are stored around the base of the lodge, the bulk of which are eaten by youngsters during the winter. Beavers may travel good distances from their homes to find food. If they find a good source, they build canals to the food source as a way to float the food back to their lodges.


Beavers pair for life. Mating takes place in January or February. Two to eight kits are born after a gestation period of 65 to 128 days. At birth each weighs about 1 pound and is about 15 inches long, including 3 inches of tail. They can eat solid food at one month, but are not fully weaned until 6 weeks of age. Young remain with their parents for 2 years, becoming sexually mature at 2-3 years. A beaver may live up to 20 years in the wild.

Scientific Classification

phylum Chordata
subphylum Vertebrata
class Mammalia
order Rodentia
suborder Sciurognathi
family Castoridae
genus & species Castor canadensis


Animal Diversity Web

See Also


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This page was last updated on September 01, 2018.