Beaver

Scientific name: Castor fiber

Identification

Photo by Laurie Campbell

Beavers are the largest native European rodent.  European beavers measure 70-100cm in length and weigh 25-30kg.  They have a long, flattened tail which is used as a rudder, and webbed feet used for propulsion.  The thick brown coat is waterproof.  They have two orange front teeth that stick out beneath the upper lip.

Habitat and Distribution

Beavers are semi-aquatic mammals.  They generally inhabit lowland riparian broadleafed woodland bordering slow-moving streams or static ponds, but are also found at higher altitude on wooded mountain plateaus.  They dig burrows in river banks or, where not possible, build a structure known as a lodge, in which they live and raise young.  Beavers dam water bodies to create ponds, although European beavers build fewer dams than their American counterparts.   The beaver is now present throughout much of Europe but the UK remains one of the only countries of its former range to which it has not been reintroduced.

Global distribution of the European beaver (IUCN 2011)

Diet

Beavers are completely vegetarian.  There is a common misconception that they eat fish but in fact they feed solely on plant matter, consuming both the lush green parts and the woody stems and trunks of trees.  Favoured species are aspen and willow and plant wise they eat a variety of sedges and rushes.  They fell trees by gnawing through the trunk and then break off leafy branches which they either consume or carry off to store for winter.  During winter they eat more woody matter.

Reproduction

Beavers reach reproductive age at two years old and mate for life.  They live in family groups consisting of two adults, kits of the year and previous offspring up to 1.5-2 years old.  One litter of 2-3 kits is produced each year. Females normally comes into oestrus between January and February and the gestation period is 60-128 days.  The female gives birth inside a lodge and the whole family cares for the kits once they are weaned after approximately six weeks.

Status and Threats

The Eurasian beaver is classified by the IUCN as ‘Least Concern’.  Historically it was heavily hunted and driven to extinction in many parts of its range, but it has now recovered or been reintroduced to most of its former range and these populations are generally stable or increasing.  It remains extinct in the wild within the UK.