Section Navigation Section Navigation. Printer friendly. Beavers grow throughout their lives. Although they average 40 to 70 pounds, they can weigh as much as pounds.
Beaver Behavior and Biology
Beaver Species Profile, Alaska Department of Fish and Game
Beavers are the largest rodents in North America and one of the few species that significantly modify their environment. North American beavers have stocky bodies with a yellow-brown to almost black coat and a broad, flat, scaly tail. Their large, orange incisors grow continuously throughout their lifetime. The beaver's stocky body enables it to conserve heat. These teeth are self-sharpening and can cleave a willow the size of a person's finger in a single bite! If the incisors become too long, they can prevent the beaver's mouth from closing enough for its grinding molars to meet, which could lead to starvation.
Facts About Beavers
The North American beaver Castor canadensis is one of two extant beaver species the other being the Eurasian beaver, Castor fiber. In the United States and Canada , the species is often referred to simply as "beaver", though this causes some confusion because another distantly related rodent, Aplodontia rufa , is often called the " mountain beaver ". Other vernacular names, including American beaver  and Canadian beaver ,  distinguish this species from the other extant beaver species, Castor fiber , which is native to Eurasia. The North American beaver is an official animal symbol of Canada and is the official state mammal of Oregon and New York. This beaver is the largest rodent in North America and competes with its Eurasian counterpart, the European beaver , for being the second-largest in the world, both following the South American capybara.
Adult beavers typically weigh 45 to 60 pounds, but have been known to grow to pounds. Beavers and humans are alike in their ability to greatly alter their habitats to suit their own needs. To obtain food and building materials, beavers are well known for their ability to topple large trees using nothing but their specially adapted incisor teeth and powerful lower jaw muscles. Beaver teeth never stop growing, so they do not become too worn despite years of chewing hardwoods. Their four front teeth incisors are self-sharpening due to hard orange enamel on the front of the tooth and a softer dentin on the back.