A beaver is a semi-aquatic rodent that is famous for its skill at building.

Beavers live along rivers and streams in North American, European and Asian forests.

They build homes, known as lodges, in ponds. If there is no existing natural pond, a beaver will build a dam to create an artificial pond.

The pond provides a barrier that protects the beaver against predators.

American beaver, photo by Steve HDCBy building dams, beavers create wetlands that are habitats for other forms of animal and plant life.

Sometimes, beaver dams will cause human property nearby to become flooded.

The beaver dam at Wood Buffalo National Park in Alberta, Canada is believed to be the longest beaver dam on Earth. The dam is about half a mile long.

Beavers also build canals to transport building materials over water.

A beaver lodge is made of mud and broken branches. Its entrance is under water.

Beaver lodge at Wood Buffalo National Park; photo by Ansgar Walk

The beaver is the second largest rodent on Earth. A beaver may weigh more than 60 pounds.

The only larger rodent is the capybaras.

Beavers' bodies are adapted for swimming. Beavers have webbed feet and flat tails. Their ears and noses close up when they are swimming. Their eyes are covered by a transparent membrane.

They have oily, waterproof fur.

A beaver can remain underwater for 15 minutes before it has to come up for air.

When a beaver is frightened, it will dive while slapping the water with its tail. This sound warns other beavers nearby of potential danger.

Beavers' bodies also have features that make their jobs as construction workers easier.

Their front teeth act like chisels, making it easier for them to fell trees.

They can use their flat tails to plaster mud.

Beavers do not hibernate. When it is cold, they stay in their lodges, where they remain warm and can eat food that they have stored underwater.

They mate for life. The female beaver gives birth in the spring. Both parents care for the young.

Young beavers remain in the nest for two years. When a new litter is born, the beavers that already are a year old (yearlings) will help to take care of their younger siblings.

A young beaver is known as a kit, kitten or pup.

Beavers have been hunted for their fur and for food.