beaver

Beaver is the common name for two closely related species of large, semi-aquatic rodents in the family Castoridae: the North American beaver (Castor canadensis) and the Eurasian beaver (Castor fiber). They are among the largest living rodents, with stocky bodies, dense fur, and large orange, continuously growing incisors that they use to gnaw wood. The tail is broad, flat, and scaly, serving as a rudder in water and as a status or signaling device on land.

Beavers inhabit freshwater environments such as rivers, streams, lakes, and wetlands. They are renowned for constructing dams from branches, mud, and stones, which raise the water level upstream to create ponds that provide protection from predators and access to food during winter. A beaver lodge, built with sticks and mud, provides shelter in the water or along the bank. Dams and ponds created by beavers support complexes of wetlands that benefit many other species.

Diet consists mainly of tree bark, cambium, leaves, and aquatic vegetation. Beavers gnaw on the bark of deciduous trees, especially aspen, willow, and poplar, and they cache food underwater near their lodges for winter consumption. They are largely nocturnal or crepuscular and live in family groups that typically include a breeding pair, several offspring, and sometimes helpers.

Beavers communicate with vocalizations and scent marking, including the use of castoreum produced by anal glands to mark territory and attract mates. Reproduction occurs once a year, with a litter usually consisting of two to four kits after a gestation on the order of about 105 days.

Historically hunted for fur and castoreum, beavers have since become important ecosystem engineers; their dam-building activities create wetlands that increase biodiversity. IUCN assessments place Castor canadensis as Least Concern and Castor fiber as Near Threatened.