American Beaver (Castor canadensis)

Description
American Beaver

Size

  • The American beaver, Canada's national emblem, is the largest North American rodent.
  • Adults weigh about 20 kilograms (44 pounds), but may get as large as 35 kilograms (77 pounds).

Appearance

  • Beavers are remarkably adapted to their aquatic and logging lifestyle. Though the belief that their flat, scaly tail is used as a trowel for mud is a myth, the tail does have multiple functions, including:
    • As a rudder when swimming
    • As a prop when standing
    • As a lever when dragging logs
    • As a warning device when slapped on the water
  • The digits (fingers) and claws of the forepaws are long and delicate to aid in the handling of wood.
  • The digits of the hind foot are broad with webbing of skin between the toes to propel the animal through the water.
  • The rich, deep fur of beavers has been prized by furriers for centuries. The long and dense undercoat provides excellent insulation; and the long guard hairs that grow through the under-fur form a rich reddish-brown outer coat.
Distribution
  • Beavers occur in all natural regions except the alpine subregion.
Natural History

Habitat

  • The beaver is one of the few animals that changes its environment to suit its lifestyle. Beavers construct dams on streams to create ponds.
  • Beaver ponds flood the surrounding woodland, providing protection for the beavers and allowing them to fell trees close to shore.
  • Beaver ponds are usually occupied by one family of beavers. The average colony contains one pair of adults, about four young of the year (kits), and young from the previous year (yearlings).
  • A beaver house is constructed of sticks and mud, and is usually situated well away from shore so that land-based predators cannot get at it in summer. In winter, the mud freezes, forming an impregnable fortress against predators that might venture across the ice.
  • Some beavers live along rivers and do not build dams or lodges. Instead they burrow into the bank of the river and fell trees for food near their home.

Food

  • Beavers eat the bark of poplar, willows, cottonwood, and other trees and shrubs.
  • In summer, they also eat pond weeds, water-lilies, and cattails.
  • Beavers may raise the height of their dams so that they can bring more food into reach.
  • When the food supply is finally exhausted at the dam's maximum height, the beaver family abandons the pond and moves to another site.
Reproduction and Growth

Breeding Behaviour

  • Mating takes place in January and February, with young being born from April through June.

Growth Process

  • Young do not assist in the work of the colony until their second summer.
  • Juveniles become adults in their second winter, and are driven from the colony to start a dam and a colony of their own.
Conservation and Management

Status

The beaver is classified as Secure in the current General Status of Alberta Wild Species report. See:

Current management

Trapping

 

Page Information

Updated: Apr 17, 2009