The beaver (genus Castor) is a large, primarily nocturnal, semiaquatic rodent. Castor includes . Beavers fell small trees, especially young second-growth trees, for food. Broadleaved trees re-grow The beavers cover their lodges late each autumn with fresh mud, which freezes when frosts arrive. The mud becomes almost. Beavers begin storing food in the water near their Both parents work together to raise the young, bringing the babies fresh branches and leaves to nibble on.