The North American beaver is a strict herbivore with a highly varied diet determined by the seasons and local availability of plants. Beavers are selective eaters who consume a wide range of vegetation throughout the year, adapting their foraging to maximize nutrient intake. Their feeding habits are linked to their environment, as they actively shape their habitats through dam-building to ensure a steady supply of food and safe access.
Primary Food Sources: Woody Vegetation
The beaver is famous for felling trees, but the hard wood of the trunk is not the primary food source. The most sought-after part of the tree is the cambium layer, the soft, living tissue found directly beneath the outer bark. Beavers strip away the outer bark to access this sugar-rich inner layer, consuming it in large quantities, especially during colder months when other foods are scarce.
Beavers prefer certain deciduous trees that are soft, have high water content, and are easy to digest. Favorite woody foods include aspen, willow, birch, cottonwood, and poplar. These species often grow close to the water, reducing travel distance on land and minimizing exposure to predators. Cutting down a tree allows them to access the tender, smaller branches and bark from the upper canopy. Beavers generally avoid conifers, such as pines and firs, unless deciduous food sources have become depleted.
The Importance of Aquatic and Herbaceous Plants
The beaver’s summer diet relies heavily on softer, herbaceous vegetation. During the spring and summer, when plants are actively growing, beavers consume a wide array of aquatic and terrestrial plants. This vegetation is often easier to digest and provides a higher protein-to-calorie ratio than woody material.
Beavers frequently eat the leaves, stems, and roots of plants that grow in and around their ponds. This includes tender species such as cattails, sedges, grasses, and ferns. Aquatic plants, particularly the rhizomes and tubers of water lilies, are an important component of their diet. These soft plants are abundant in the wetlands that the beavers themselves create through their dam-building activities.
Seasonal Shifts and Winter Food Caching
The beaver’s diet changes in response to the seasons and the freezing of its aquatic environment. As temperatures drop and green vegetation dies back, beavers shift their focus to woody plants. They must prepare for a period when surface foraging is impossible.
In late fall, beavers engage in “caching,” creating a large, submerged food pile near the entrance of their lodge. This cache consists of cut branches and logs from preferred trees, anchored into the mud at the pond bottom. Once the pond surface freezes over, beavers access this underwater pantry by swimming beneath the ice from their lodge. This stored food, composed of bark and cambium, ensures a reliable source of nutrition throughout the winter until the spring thaw.