I spent my Valentine's Day weekend backpacking with my husband in the George Washington National Forest, just along the West Virginia/Virginia border. As we hiked along dense streamside forests, I noticed an open area ahead. From the distance I could see nothing but stumps of all sizes. As we got closer, I discovered that this part of the forest had been harvested by one of its natural inhabitants-the beaver

Found throughout North America except for the northern regions of Canada and the deserts of the southern United States and Mexico, beavers are primarily aquatic animals.

The beaver is one of the largest rodents in this hemisphere-only the capybara in South America is larger. They waddle on land but are graceful in the water, using their large, webbed rear feet like fins and their paddle-shaped tails like rudders. They can swim at speeds of up to 5 miles an hour and remain underwater for 15 minutes. A set of transparent eyelids function much like goggles. Their fur is naturally oily and waterproof.

Beavers re-engineer the landscape as few other animals can. They transform less suitable habitats by building dams. Felling and gnawing trees with their large incisor teeth and powerful jaws, they create massive log, branch and mud structures to block streams, creating ponds. Beavers build dams to slow the flow of water and then build stable lodges for shelter. The dams are engineered according to the speed of the water; in slow water the dam is built straight, but in fast water, the dam is built with a curve in it.

They also use trees for food, eating leaves, bark, twigs and roots as well as aquatic plants. Cellulose, which usually cannot be digested by most mammals, is a major component of their diet. Beavers have a microorganism in their cecum (a sac in the large intestine) that digests this material. They will travel good distances from their homes to find food. If they find a good source, they often build canals to the food source as a way to float the food back. Logs and twigs are often stored underwater for winter feeding.

Domelike beaver homes, called lodges, are also constructed of branches and mud. They are often strategically located in the middle of ponds and can only be reached by underwater entrances. These dwellings are home to extended families known as colonies.

Beavers are monogamous, but if one mate dies, the other will seek out a new one. They mate between January and March in colder climates, and in late November or December in the south.

Beavers give birth to one litter of kits per year, usually between April and June. The young develop inside the female's body. Kits are born fully furred, have open eyes and can swim within 24 hours.

The young usually stay with their parents for two years and then are driven away leave to make a colony of their own, usually several kilometers away, Beaver colonies consist of up to eight related individuals. Beaver families are very territorial and will defend their home against other families. Beavers also warn others of danger by slapping their tails against the water, creating a powerful noise.

An adult beaver's size is a deterrent to most predators, although bears, wolves, wolverines and river otters pose a danger to kits. People have proven to be, by far, the most dangerous predator to beavers.

Beavers have been hunted and trapped extensively for their pelts. By about 1900, beavers were almost gone from their original habitats. Pollution and habitat loss have also affected the survival of the beaver. In the last century, however, beavers have been successfully reintroduced to many of their former habitats.

Beavers can be beneficial to the environment. They are instrumental in creating habitats for many aquatic organisms, maintaining the water tables and controlling flooding and erosion, through the building of dams.