High Quality Content by WIKIPEDIA articles! Beaver dams are dams built by beavers as protection against predators such as coyotes, wolves, and bears, and to provide easy access to food during winter. Beavers work at night and are prolific builders, carrying mud and stones with their fore-paws and timber between their teeth. Beavers can rebuild primary dams overnight, though they may not defend secondary dams as vigorously.