American beaver

Latin Name
Castor canadensis




Large incisors, a thick, flat tail and waterproof brown fur make the American beaver easy to recognize. The species, which can weigh up to 65 pounds, is one of the largest members of the rodent order. Adults can reach up to four feet in body length, with the tail extending an additional one-two feet beyond that.



Alaska to Mexico


The American beaver was nearly driven to extinction in the 1800s due to overhunting. North American populations have rebounded, however, and the species can now be found through much of its original range.


Streams and small lakes surrounded by tree groves


In the spring, the American beaver primarily feeds on leaves, shoots and grasses, but in the fall the mammal switches to a diet mostly consisting of trees and branches. Bacteria in the beaver’s stomach help it digest wood.

Beavers build their dams from mud, stones, sticks and branches. The large mounds with underwater entrances provide the beaver with protection from predators and help to flood lakes and streams, providing additional habitat. Beavers will also store branches and sticks in the water near their dams. The cool water preserves the food for the rodents to eat in winter.

Life History

Beavers live in family groups consisting of a mating pair and their young offspring. The group occupies a defined territory, working together to build their dam and drive off other beavers that intrude. The animals communicate via scent and by slapping the water with their tails, a signal that warns other group members to seek cover.

Male and female beavers mate for life, producing one litter of offspring, or kits, every year. All group members contribute to bringing food to the den to feed the young. Newly born beavers can swim within hours after birth, and they usually begin to explore the area outside their dens with their parents within a few days.

Special Adaptations
  • The American beaver's tail helps it steer through the water and also provides a powerful paddle for extra speed.
  • Translucent membranes cover the beaver's eyes when it dives, enabling it so see underwater. The mammal's throat can also be sealed tight by its tongue, helping it carry (and chew) sticks underwater.
  • Beaver's teeth are durable and grow constantly throughout their lives, a necessity for gnawing through trees. A group of the animals working together can fall a tree that's a foot thick in less than four hours.

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