FaunaHub

Beaver

MammalRodentHerbivore

A North American beaver sitting at the water's edge.

North American beaver (Castor canadensis).

Image: GlacierNPS, Public domain, via Wikimedia Commons (NPS).

Overview

Beavers are large, semi-aquatic rodents famous for building dams and lodges. There are two species: the North American beaver (Castor canadensis) and the Eurasian beaver (Castor fiber). This page uses the North American beaver as a reference. Beavers are widely described as "ecosystem engineers" because their dam-building reshapes streams into ponds and wetlands that benefit many other species.

Habitat & Range

Beavers live in and around fresh water — streams, rivers, ponds, and wetlands — usually in wooded areas that supply the trees and shrubs they use for food and construction. By damming watercourses they create their own ponds, within which they build lodges for shelter. Their range covers much of North America and, following reintroductions, expanding parts of Europe and Asia.

Diet

Beavers are herbivores. They feed on the bark, leaves, twigs, and buds of trees and shrubs such as willow, aspen, and birch, and on aquatic and herbaceous plants in summer. They fell trees with their powerful incisors both to eat and to build, and in colder regions they cache branches underwater to feed on through winter.

Behavior

Beavers live in family groups (colonies) and are mainly active from dusk into the night. They are industrious builders, constructing and maintaining dams and lodges, and they store food for winter. Beavers communicate with scent marks and warn of danger by slapping the water with their broad, flat tails. Their constant tree-felling and damming continuously reshapes their local waterway.

Human Interaction & Conservation

Beavers were historically trapped extensively for fur, which greatly reduced their numbers, but both species have recovered in many areas and are increasingly valued for the wetlands they create, which can store water and support biodiversity. Their dam-building can also conflict with human land and water use. Conservation status should be checked against current sources; both species are now generally widespread but locally managed.

Appearance & Recognition

Beavers are heavy-bodied rodents with dense, waterproof brown fur, small ears and eyes, large orange-tinted incisors, webbed hind feet for swimming, and a distinctive broad, flat, scaly tail. They are the largest rodents in the Northern Hemisphere. The two species are very similar in appearance and are most reliably told apart by range and technical features rather than by eye.

Similar Animals

Beavers are rodents, the same broad group as the guinea pig and hamster covered elsewhere on FaunaHub, though far larger. In the water they can be confused with otters or the smaller muskrat, but beavers are bulkier and have the unique flat tail. The otter, by contrast, is a carnivorous mustelid.

More photos of the beaver

A beaver swimming and feeding in a pond.

A North American beaver feeding near water.

Image: Ryan Hodnett, CC BY-SA 4.0, via Wikimedia Commons.

Frequently Asked Questions — Beaver

Why do beavers build dams?
Beavers dam streams to raise and deepen the water, creating ponds that protect their lodges, give safe underwater access, and provide year-round water near their food supply. The resulting wetlands also benefit many other species, which is why beavers are called ecosystem engineers.
What is a beaver's lodge?
A lodge is the dome-shaped shelter beavers build from branches and mud, usually with underwater entrances. Inside is a dry chamber above the water line where the family rests and raises young.
How many beaver species are there?
Two: the North American beaver (Castor canadensis) and the Eurasian beaver (Castor fiber). They look very similar but are separate species with different ranges; this page uses the North American beaver as its reference.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.