Eurasian beaver
Eurasian beavers are one of the largest living species of rodents and are the largest rodent native to Eurasia. They weigh around . In Norway, adult males average while females average , while another study found adults from the same country to average . By the average weights known, the Eurasian beaver appears to be the world's second heaviest rodent behind the capybara, but averaging slightly larger and heavier than the North American beaver. While the largest specimen confirmed on record weighed , the Smithsonian has reported that this species can exceptionally exceed . Typically, the head-and-body length is and the tail length is .
Beaver
The beaver (genus Castor) is a large, primarily nocturnal, semiaquatic rodent. "Castor" includes two extant species, the North American beaver ("Castor canadensis") (native to North America) and Eurasian beaver ("Castor fiber") (Eurasia). Beavers are known for building dams, canals, and lodges (homes). They are the second-largest rodent in the world (after the capybara). Their colonies create one or more dams to provide still, deep water to protect against predators, and to float food and building material. The North American beaver population was once more than 60 million, but as of 1988 was 6–12 million. This population decline is the result of extensive hunting for fur, for glands used as medicine and perfume, and because the beavers' harvesting of trees and flooding of waterways may interfere with other land uses.