Castor fiber

  1. Wildlife
  2. Mammals
  3. Beaver


The largest Eurasian rodent. Originally widespread over northern and temperate Eurasia, but hunted nearly to extinction in Europe for its fur and for castoreum, a secretion of its scent gland believed to have medicinal properties. Now being reintroduced to numerous European localities, some with great success. By 2003, the estimated European population was 600,000. Became extinct in the UK during the 16th century.

Beavers are busy animals with an ability to alter their surroundings. Their impacts on vegetation are most striking. They move woody and other plant materials throughout their home range, some of which regenerates in new locations. They fell small trees and bushes for food and dam construction. Beavers live in family groups of three to five, comprising an adult pair, kits, yearlings and one or more sub-adults. Females normally reach reproductive age at three years, and can produce one litter each year of two to three kits. Longevity is typically seven or eight years but specimens of up to 25 years have been recorded.

Diet is entirely herbivorous. In late spring and summer it eats mainly aquatic plants, grasses, ferns and shrubs. At other times, woody species form the major part of its diet. 

How to identify

As large as a labrador dog but with shorter legs, beavers are robust, heavily built, and weigh up to 38 kg. Body length, 75 to 90 cm. Two distinctive features are a broad, flat tail, 29 to 38 cm long covered with scales, and webbed feet. Eyes and ears are small. The fur of southern forms is lighter in shade than that of northern forms. Essentially aquatic. Walks slowly and clumsily but swims and dives strongly. Mainly nocturnal, emerging just before sunset, but can be active by daylight in quiet areas. Does not hibernate. Shy and wary; usually silent although sometimes growls, hisses or screams. Nests in underground holes in high banks with underwater entrance.

Where to find it

In recent years small numbers were reintroduced to locations in England, Wales and Scotland from mainland Europe. Preferred habitats are open woods alongside rivers, old river beds and lakes. Woodlands include oaks, ashes, alders, elms, willows, poplars and birches with undergrowth. If you want to see them in the wild you can visit the Scottish beaver trial at Knapdale, Argyll.

When to find it

  • January

How can people help

You can help by supporting beaver reintroduction trials being run by Wildlife Trusts. Visit the websites of the Scottish Beaver Trial, the Devon Wildlife Trust's Beaver Project and the Welsh Beaver Project to find out more.

Species information

Common name
Latin name
Castor fiber
Length: up to 1m plus a tail of 30cm Weight: 18g Average lifespan: 7-8 years
Conservation status
Extinct in Britain until 2009. Classified as Least Concern (LC) on the IUCN Red List.