The beaver is a vegetarian that has evolved mainly eating bark from trees such as Aspens, Cottonwoods, Willow, Balsam, Cherry and Maple, to name some species. In most cases beavers prefer the young smooth bark. As the trees get older bark becomes corky and is harder to digest. Beavers will cut down the larger trees to feed on the younger branches and small saplings. There is a variety of plants other than trees the beaver has in its diet. Some include pond weed, arrowhead, cattail, mil-foil, pond lily, shoots, wild rose, cow parsnip, leaf stems and various roots, even algae from rocks. The nutrition required to supply the energy beavers need to live, they evolved large stomachs and intestines, aided by a unique pouched organ name a cecum, with a cardiogastric gland producing highly acidic juices that enter the stomach. This helps dealing with the huge amount of cellulose intake in the beavers diet. Spring and summer the beaver has many places to find and collect food. In cold northern climates food is not possible to find so the beaver builds a cache of food under the water to sustain their families.
Beavers start collecting food when frost comes, cutting trees and gathering branches, they bring them down close to the lodge. To keep the trees and branches from rising beavers dig the trees into the muddy bottom then weave other branches in a pattern that holds the cache in place. Studies have shown these winter caches do not last the beavers and are mainly stored for the kits and yearlings. Adult beavers by spring may lose some weight allowing sufficient food for the younger members to carry on growing. Southern latitude beavers do not build winter caches but it is believed they instinctively would if cold weather arises.