The beaver is North America's largest rodent. Beavers mate for life, breeding in January and February. They build lodges with sticks and mud, complete with underwater entrances. They then construct dams to maintain the water level at their lodge. The importance of these dams for flood control and soil conditioning has only recently been recognized. Beavers eat only plants, including bark, twigs, and leaves from a variety of trees and shrubs such as poplar, maple, pine, and scrub oaks.