American Beaver

Castor canadensis

size

Beavers are among the largest rodents. Their bodies are 28 inches with tails that are 12 inches long and 4_ inches wide. They weigh from 35 to 60 pounds.

characteristics

Beavers have brown fur that keeps them warm and dry even in cold water. The undercoat traps a layer of air to insulate the skin. Their nostrils and ears have valves to stop water from entering. Beavers have non-webbed front feet with strong digging claws and webbed hind feet that help when swimming.

The most identifiable characteristics of beavers are the front teeth and the broad tail. A special flap of skin behind the front teeth allows beavers to gnaw bark underwater without getting their mouth full of water or wood chips. A beaver’s teeth never stop growing and have to be worn down with use. Its broad scaly tail is used as rudder. The tail is also used to make warning sounds by slapping the water.

behavior

Beavers are active during the day (diurnal) but become nocturnal with human encroachment. They don’t hibernate. Beavers build dams to create deep water needed for protection. The dams are made of branches, grass and mud. The main lodge of a beaver dam is 6 to 10 feet in diameter. Some people say beaver dams cause floods, but on the other hand, they help control runoff, and aid in keeping erosion in check and maintaining a suitable water table for fish and waterfowl.

Beavers live in colonies of four to eight related beavers. Each fall, beavers collect and anchor a supply of green branches underwater to prepare for the winter months.

reproduction/lifespan

The gestation period for beavers is about 3 months. Babies are born in litters of two to four, usually in the spring, and young beavers can swim within one day of birth. Beavers leave their parents at the age of 2. Beavers live from 13 to 20 years.

diet

Beavers are herbivores. In the wild they eat leaves, roots, water plants, herbs, algae and the juicy green inner layer of bark. They do not just eat wood. At the zoo, they are fed rat chow, monkey chow, carrots, apples, broccoli and browse.

habitat/range

Beavers are found in the streams, rivers, marshes and small lakes of Canada and the US.

status

The population of beavers is stable to increasing in what remains of suitable habitat. The threats to beavers are civilization, habitat destruction, water pollution, and hydroelectric dam construction. They are regulated by the Oregon Department of Fish and Wildlife.

other

The beaver is the largest rodent in North America and the “engineer” of the animal kingdom. It can fell an 8-foot tree in only five minutes. In the 1700s and early 1800s, the beaver probably contributed more to the development of United States and Canada than any other animal. The value of its pelt motivated trappers to move farther and farther west, and settlers followed the trappers. Its pelt was also used as currency in colonial times.