They create dams through instinct and in response to the sound and, to a lesser extent, the motion of running water. The lodge contains a dry inside chamber which provides cover from the elements and a place to raise young. There are usually several underwater entrances to the lodge. Beavers also may build dens along rivers by digging underneath overhanging root masses or into the bank. The entrance to a bank den may be covered with sticks and mud.
Beavers are active year round.
They are mainly nocturnal, but are sometimes observed during daytime. Activity is concentrated in the vicinity of the lodge and dam, but, if necessary, beavers may travel several hundred feet from the water in search of food and materials for lodge and dam maintenance. In the fall, a cache, or feed bed, is usually placed just outside of the lodge by anchoring sticks and branches in the muddy bottom. The beavers will feed on this food supply during winter when the pond or flowage is iced over. Territorial by nature, beavers will not tolerate other beavers within their colony's home range.