Beavers

A beaver swims through water that reflects fall colors.

NPS/ Anne Longman

Busy Beavers

Nature’s carpenters, beavers are best known for their unique building behavior. Flat tails, two large front teeth, and webbed feet all contribute to their distinct look. These large rodents can be spotted in waterways across the monument, building dams and chewing on sticks.

Signs of beavers include:

• Tree stumps that appear to be chewed on
• Lodges or dams made of piled sticks and mud
• Webbed animal tracks
• Loose sticks with sharp, chewed down points

Behavior

Beavers spend most of their time furiously working to build dams and lodges. To do so, they cut down trees, collect sticks, construct habitats, and scout new locations. Although sometimes spotted during the day, beavers are primarily nocturnal and can be seen working mostly at night. A good time to catch beaver activity is at dusk.

 

A beaver dam and standing water that it has created.

NPS/ Anne Longman

Habitat

Beavers live in waterways surrounded by forest, where they focus on building two main structures.

Dams

A wall of sticks and dirt that reduces water flow on a moving body of water, flooding the area. Beavers build dams to increase depth of water. Beaver homes require water deep enough that it cannot freeze solid in the winter. This keeps underwater entrances to lodges clear and ensures that stored food does not freeze.

Lodges

Lodges are hollow stick structures with two underwater entrances. The interior structure is warm and dry. Beavers live, eat, and raise young inside these structures. One family can build multiple lodges in a single territory.

 

Diet

Beavers eat leaves, sticks, and other vegetation. Although beavers spend most of their time chewing on trees, they do not eat the dense wood. Beavers enjoy the soft, fleshy layer of a tree just under its bark, called cambium. The rest of the tree is cut down as building material. Aspen and birch are two of the most popular tree types among beavers.

 

A tree showing signs of beaver activity.

NPS/ R. Wang

 

Diagram showing the two types of beaver tracks.

Illustration: NPS/ Anne Longman

Physical Characteristics

Beavers, like all rodents, have teeth that never stop growing. As beavers gnaw on sticks, their teeth grind down to a manageable length. As a result, their teeth are in a constant state of flux.

Beavers have large, flat tails that help them steer while swimming. Beaver tails also serve as a helpful counterbalance when they sit on land. Tails help prop up the beaver while it rests, eats, or moves around.

Beavers have webbed feet, which help them swim easily. Look for beaver tracks in mud near dams or lodges.

 

Impact on the Ecosystem

Beavers shape wetland topography in important ways. Dams create broader wetlands with deeper, slower waters that allow for more aquatic plant growth. This is beneficial to a variety of animals, including moose, whose diet are rich in leafy vegetation. When beavers cut down trees, short, brushy, foliage can grow in the trees’ absence. New, different plant life supports diverse animal life. Rising water levels kill trees, creating valuable nesting spaces in hollow dead tree cavities. Certain birds may even nest on top of a beaver lodge, where warmth from the interior rises. Beavers have profound, cascading impacts on their surrounding environment.

 

These aquatic plants grow as a result of deep, slow-moving water.

NPS/ R. Wang

Relationship to Humans

Beavers have a long and complicated history with humans. They are often viewed as destructive pests, sometimes responsible for flooding sidewalks, trails, and even houses. Recent developments in technology and engineering have allowed land managers to take a new approach in the complicated relationship with beavers. Wire fencing, pipes, and clever material placement enable workers to create water flow around beaver dams. This allows beavers to continue working, avoiding displacement, while simultaneously preventing destructive floods. Learn more about these new methods from the Maine Department of Inland Fisheries and Wildlife.

Want to know more about beavers? Explore additional information from Acadia National Park.