How big do beavers get?

Updated February 21, 2017

Beavers are among the largest rodent mammals in the world. Two species of beavers exist in the world today, the American beaver and Eurasian beaver. Both beaver have similar physical characteristics, including their length and weight. The primary difference between the two species is environmental surroundings and distribution range. Both beaver species have abundant populations, even though their populations decreased in the 17th and 18th centuries due to the fur trade.

North American Beaver

The North American beaver (Castor canadensis) is all the beaver specimens in the United States and Canada. These beavers have 2 to 3-foot long bodies and, with their tails, can reach lengths of 4 feet. The North American beaver's tail is approximately 16 inches long. Adult beavers weigh between 15.9 to 34 Kilogram, making them one of the largest rodents in North America. Young beavers, called kits, weigh approximately one pound in infancy. Kits already have teeth when they are born. North American beavers mature after 2 to 3 years.

Eurasian Beaver

All beavers living on the European continent are known as Eurasian beavers (Castor fibre). When male Eurasian beavers are adults, they grow up to 3 feet long and weigh 20.4 to 22.7 Kilogram. Females are larger than males, growing between 3 to 4 feet long and weighing approximately 22.7 Kilogram. Both lengths do not include the beavers' tails, which are usually 1 foot in length. Eurasian beavers are the largest rodents in Europe.

Habitat and Range

North American beavers are found throughout the United States and Canada, except for the American Southwest region. Eastern Europe, Scandinavia and Russia are the most common regions to find the Eurasian beaver. Both beaver species live in similar habitats such as rivers, ponds and marshes. Whenever a family of beavers finds territory, they rarely go more than 60 to 70 feet away. On rivers, a beaver's territory may extend from 328 to nearly 2 miles along the banks.

Social Structures

Beavers are highly social animals and live groups of 4 to 8 members. These mammals are monogamous -- having only one mate. Once they find a partner, male and female beavers usually mate for life. In a beaver family, the dominant female is the only one responsible for reproduction. Kits, or young beavers, stay with the family for three years and help their parents build dams. After the third year, the beaver parents encourage their children to leave the colony.

Physical Characteristics

North American and Eurasian beavers both have webbed feet that help them become efficient swimmers. The beaver's flat, hairless tail is used as a rudder, making beavers quick swimmers. Beavers are also able to see underwater since they have clear eyelids. These animals have 5-inch incisor teeth, which allow them to chop wood with ease. The beaver uses its teeth and fur-lined lips to carry wood for building their dam.

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About the Author

Skip Davis has been writing professionally since 2005. His work has appeared in "Southern Literary Magazine," on various websites and in graphic panels at the Jackson Zoological Park in Jackson, Miss. Currently living in Southern California, Davis received his Bachelor of Arts in theater at Belhaven College.