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  Rodentia · Castoridae · Castor canadensis

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Castor canadensis

American Beaver

Order: Rodentia
Family: Castoridae

Image of Castor canadensis
Click to enlarge. (103 kb)

Conservation Status: Least Concern.

The largest North American rodent and the only one with a broad, flat, scaly tail, the Beaver is now common and widespread, even in areas it did not inhabit during pre-colonial times. The modifications it makes to the environment by felling trees and building dams result in changes to plant, animal, and microbial communities that are sometimes desirable and sometimes not. The Beaver itself is not easily seen, being nocturnal and secretive, but it can be spotted in ponds, lakes, or large streams at twilight by a quiet observer. Its pelage is brown, with gray underfur, and is prized by trappers. The webbing on its hind feet help it to swim; claws on the digits of its forefeet give it dexterity in handling food; comblike claws on its hind feet help it in careful grooming; and it can close its mouth behind its front teeth, so that it can carry woody material without taking in water. Beavers cache and consume the inner bark of both deciduous and evergreen shrubs and trees, as well as terrestrial and aquatic plants. Their young, called kits, leave the colony at the age of six months.

Also known as:
Canadian Beaver, North American Beaver

Sexual Dimorphism:

Range: 1,000-1,200 mm

Range: 16-30 kg


Kuhl, H., 1820.  Beitrage zur zoologie und vergleichenden anatomie, p. 64.  Verlag der Hermannschen Buchandlung, Frankfurt am Main, Abt 1. 151 pp.


Mammal Species of the World (opens in a new window).

Mammalian Species, American Society of Mammalogists' species account *
* PDF reader available here (opens in a new window).

Distribution of Castor canadensis

Image of Castor canadensis
Click to enlarge. (55kb)

Skull of Castor canadensis
Click to enlarge. (21kb)

Image of Castor canadensis
Beaver (Castor canadensis) house on wetlands, Cook County, Minnesota.
Click to enlarge. (373kb)

Bones and Teeth
Castor canadensis
First two right upper molars (right to left), with dentine stippled and enamel unshaded. Click to enlarge. (23kb)