Castor canadensis (Kuhl 1820)

One of the earliest accounts of beaver natural history was written by Samuel Hearne in the late 1700s. His journal entry on beavers is online at:   http://web.idirect.com/~hland/sh/an020.htm.

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.

Adaptation: The shape of the Beaver skull, and the rough texture of its bone, is evidence of a powerful set of chewing muscles. The groove-like depression at the back of the snout and the round one near the jaw joint are areas where large muscles attach. The ridge of bone that marks the curvature below the back angle of the mandible is another muscle attachment site.

Links:
Mammal Species of the World
Click here for The American Society of Mammalogists species account

Beavers live in lodges, of which there are three types: those built on islands, those built on the banks of ponds, and those built on the shores of lakes. The island lodge consists of a central chamber, with its floor slightly above the water level, and with two entrances. One entrance opens up into the center of the hut floor, while the other is a more abrupt descent into the water.

The lodge, itself, is an oven-shaped house of sticks, grass, and moss, woven together and plastered with mud. Over the years, repair and elaboration leads to an increase in hut size. The room inside may measure 2.4 m (8 ft) wide and up to 1 m (3 ft) high. The floor is blanketed with bark, grass, and wood chips.

The pond lodge is built either a short way back from the edge of the bank, or partly hanging over it, with the front wall built up from the bottom of the pond. The lake lodge is built on the shelving shores of lakes. To ensure adequate water depth surrounding the lodge, beavers dam streams with logs, branches, mud, and stones.

Habitat Regions: temperate ; terrestrial ; freshwater

Terrestrial Biomes: forest

Aquatic Biomes: lakes and ponds; rivers and streams

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 6 barcode sequences available from BOLD and GenBank.

Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.

See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

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