What Is a Mountain Beaver?

The mountain beaver is a medium-sized rodent with a misleading name. It is not closely related to the beaver as it belongs to the scientific sub-order Sciuromorpha, which includes squirrels and doormice. Beavers are members of the Castorimorpha sub-order and are related to gophers. The mountain beaver gets its name from its beaver-like strong incisor teeth and its habit of gnawing tree bark.

  1. Description

    • The mountain beaver grows to between 11 and 18 inches in length and weighs close to 2 1/2 lbs. It has a broad, robust body covered in thick dark brown fur with small white spots below each ear. The animal has a broad head with a slightly arched nose and small eyes. Its legs are short with large paws and five slender toes on each foot. The animal's tail is little more than a stump, and no longer than an inch.

    Habitat and Range

    • The mountain beaver lives in the western halves of Washington and Oregon as well as into northern and central California. The species is most common in high altitude forest habitats that offer ample undergrowth cover. Less commonly, the species can be found in sea-level forests. The most important requirement for the species is areas with deep loose soil in which it can burrow. These burrows can be up to 10 feet underground and consist of a food storage area, nest and toilet chamber. The animal is territorial, with generally at most four individuals found per acre of suitable habitat.

    Diet and Predators

    • The species is solely herbivorous and feeds on a wide range of foliage, roots, grasses and ferns. Commonly eaten plants include nettles, salmonberry, dogwood, vine maple and willows. The animal can climb into trees and gnaw through thin branches to make them drop to the ground to eat. It then either feeds on the spot or drags the vegetation back to its tunnels. Predators of the mountain beaver include cougars, bobcats, large owls, bears and coyotes.

    Life Cycle

    • The animal lives a solitary life, only meeting up to breed. Mating season runs from February to April with pregnancies lasting six to eight weeks on average. The female is the sole caregiver for young and gives birth to two to four young in the burrow section of the nest. The young are born blind and hairless and take around eight weeks to ween. Mountain beavers generally reach a breeding age at around 2 years of age.