Beavers are North America’s largest rodent, famous for their ability to engineer their environment by building dams and lodges in waterways. Beavers are definitively classified as strict herbivores, meaning their diet consists solely of plant matter, with no consumption of meat or animal products.
Beavers Are Strict Herbivores
Despite the widespread image of a beaver gnawing on tree trunks, the bulk of their nutritional intake, especially during warmer months, comes from soft, fast-growing herbaceous vegetation. Beavers primarily seek out aquatic plants, grasses, sedges, leaves, roots, and tubers when they are readily available in the spring and summer. This soft plant matter is significantly easier to digest and provides more immediate nutrients than woody material.
Beavers are known to travel up to 100 meters from the water’s edge to forage for these preferred foods. This strategy allows them to maximize their energy intake from highly digestible sources before relying on tougher materials. Although they are often seen cutting trees, it is often the inner bark and twigs they consume, not the hard wood itself.
Seasonal Diet Variation and Food Storage
The beaver’s diet undergoes a significant shift as the seasons change and soft plants become scarce. In the fall, beavers begin to prepare for winter by switching their focus to woody plants. This transition is a survival mechanism, as the bark, twigs, and cambium layer of certain trees remain available under the ice. They favor fast-growing deciduous trees like willow, aspen, and cottonwood for their nutritional value.
In late autumn, beavers engage in caching, creating a winter food pile near the lodge entrance. They fell trees, cut the branches into manageable pieces, and then anchor them into the mud at the bottom of the pond. This underwater food cache is accessible throughout the winter, even when the pond’s surface is frozen solid. The stored wood acts as their primary caloric source during the months when they cannot access fresh vegetation on land.
Physical Adaptations for Processing Wood and Plants
Beavers possess unique anatomical features that enable them to sustain a diet high in tough, fibrous plant material. Their large, prominent incisor teeth are one such adaptation, growing continuously throughout the animal’s life. The front surface of these incisors is covered in hard, orange-colored enamel that contains iron, which makes the teeth remarkably strong and self-sharpening as the softer dentine on the back wears down.
Beyond their specialized teeth, beavers are equipped with a digestive system designed for a high-cellulose diet. They are hindgut fermenters, utilizing a significantly enlarged pouch called the cecum, located at the junction of the small and large intestines. This large cecum houses a complex community of symbiotic bacteria and fungi. These microorganisms produce the necessary enzymes to break down the tough cellulose and hemicellulose in plant cell walls.
This microbial fermentation process allows beavers to digest around 30 to 33 percent of the ingested cellulose. To maximize nutrient absorption from their challenging diet, beavers also practice coprophagy, re-ingesting a specialized type of feces. This mechanism allows the food to pass through the digestive tract a second time, giving the body another opportunity to extract nutrients and vitamins produced by the gut microbes.