Beavers are known for their natural trait of building dams on rivers and streams, and building their homes (known as "lodges") in the resulting pond. Beavers also build canals to float build materials that are difficult to haul over land.[2] They use powerful front teeth to cut trees and other plants that they use both for building and for food. In the absence of existing ponds, beavers must use branches. They fill in the gaps between the branches with a combination of weeds and mud until the dam impounds sufficient water to surround the lodge.
Beavers must construct dams before building their lodges. First they place poles in the ground, then fill between the poles with a crisscross of horizontally placed branches to stop the flow of water.
They are known for their alarm signal: when startled or frightened, a swimming beaver will rapidly dive while slapping the water with its broad tail that can be heard over great distances above and below water. This serves as a warning to beavers in the area. Once a beaver has sounded the alarm, nearby beavers will dive and may not reemerge for some time. Beavers are slow on land, but are good swimmers, and can stay under water for as long as 15 minutes.
Beavers are herbivores, and prefer the wood of quaking aspen, cottonwood, willow,alder, birch, maple and cherry trees. They also eat sedges, pondweed, and water lilies.[3]
Beavers do not hibernate, but store sticks and logs in a pile in their ponds, eating the underbark. Some of the pile is generally above water and accumulates snow in the winter. This insulation of snow often keeps the water from freezing in and around the food pile, providing a location where beavers can breathe when outside their lodge.
For more information,go to http://en.wikipedia.org/wiki/Beaver
