beaver

Aquatic rodent with webbed hind feet, a broad flat scaly tail, and thick waterproof fur. It has very large incisor teeth and fells trees to feed on the bark and to use the logs to construct the ‘lodge’, in which the young are reared, food is stored, and much of the winter is spent. There are two species, the Canadian Castor canadensis and the European C. fiber. They grow up to 1.4 m/4.6 ft in length and weigh about 20 kg/44 lb.

Beavers are monogamous and a pair will produce a litter of twins each year. Their territory consists of about 3 km/2 mi of river. Beavers can construct dams on streams, and thus modify the environment considerably; beaver ponds act as traps for minerals and provide fertile living conditions for other species - zooplankton biomass may be 1,000 times greater within a beaver pond than elsewhere. Beavers once ranged across Europe, northern Asia, and North America, but in Europe now only survive where they are protected, and are reduced elsewhere, partly through trapping for their fur.