The American beaver (Castor canadensis) is widely distributed across North America from Canada to Mexico, with introduced populations in Finland, Russia, and Argentina. It is an ecosystem engineer that builds lodges and dams on ponds and riverbanks to create wetlands. Adults are about 60–90 cm in body length, have webbed feet and a well-developed nictitating membrane, and feed mainly on herbaceous and aquatic plants and tree bark. They live in monogamous family groups; breeding occurs from spring to early summer, and the young are raised by both parents. Populations declined sharply due to past overhunting but have recovered through conservation measures and are currently listed as Least Concern.