Why do beavers build dams?

Beavers build dams to create a pond-like environment where they can live safe from predators. Since short legs and a wide body make the rodents vulnerable on land, beavers, which are excellent swimmers, use their large, flat tails and webbed hind feet to their advantage by nesting in the water.

Felling trees with their strong jaw muscles and teeth, beavers create massive structures out of logs and branches to block the currents of rivers and streams. In the middle of the enclosed structure rests a dome "lodge" where beavers and their kits live. To avoid detection by predators, the mud, rock and stick home is accessible only by underwater tunnels.