Why do beavers build a dam?

Beavers and their dams play an important role in nature. Because of the dramatic effects their dams have on surrounding ecosystems, these mammals are considered a keystone species. By constructing dams they create wetlands-- lush environments which attract fish, ducks, frogs and other creatures. read more

Beavers are the engineers of the rodent world. They fell trees by gnawing through their trunks, then use the branches to dam streams. The dams create a pond, in the middle of which the beaver family constructs an island made of more branches. The island, or beaver lodge, is a perfect home where the beavers are safe from predators. read more

In lakes, rivers and large streams with deep enough water, beavers may not build dams and instead live in bank burrows and lodges. If the water is not deep enough to keep beavers safe from predators and their lodge entrances ice-free, beavers build dams. read more