Type: Animal Sign. Habitat Description:Hardwood forest by a river. Natural history info: Beavers use trees for both food and building dams. Though they prefer to eat Aspen, Cottonwood, Willow and Dogwood, they will ultimately eat and fall any tree that will help them with their dam construction. They build dams in order to flood areas for protection from predators, underwater entrances to their den, and access to food supply. I found this photo interesting because we can see the hard work that a beaver once put in. I like how it sort of looks like the stump is pointing to the water in the background.