Monthly Archives: February 2019

Forest Feature: Beavers

A beaver swims across a stream

The busy, busy beaver is our February Forest Feature.

Beavers, or Castor canadensis, are sometimes called the “engineers of the wild.” They are probably best known for the elaborate dams they construct across streams, flooding surrounding wetlands.

A beaver sits upright, clutching something in its paws.
A beaver, photographed July 4 2007 by
Flickr user @sherseydc (Steve Hersey), downloaded Feb. 4, 2019. This image is shared with the owner’s provision under the provisions of a Creative Commons license (CC BY-SA 2.0).

A beaver dam creates a pond that provides habitat for the beavers, and for many other aquatic creatures. Deer and other animals may forage for grass and shrubs that grow in small meadows beavers have created by harvesting wood to build with.

The dams are built from wood, mud, and rocks. Beavers cut down small trees by chewing through them. They may even dig canals to float those trees back to their pond!

A large beaver dam on the Fremont National Forest is photographed in this file photo from the USDA Forest Service – Pacific Northwest Region archive.

The beaver is the largest rodent that is native to North America. A typical adult beaver is more than 3 feet in length, if you include their broad, paddle-like tail, and weighs more than 40 pounds!

You might be surprised to learn beavers don’t live inside beaver dams. A beaver’s home is called a “lodge” and is typically a large mound, also made from branches and mud, located upstream from a dam.

Lodges can have multiple entrances, which lead to an above-water den inside. They even have “skylights” – small holes near the top that lets in fresh air.

The Olympic National Forest’s Brown Creek Nature Loop circles a beaver pond, seen here in an April, 2017 USDA Forest Service – Pacific Northwest Region photo.

Beavers live in colonies of up to a dozen beavers, and a colony may have several lodges!

During the winter, beavers take a break from all their busy building. In places where it gets very cold, beavers will store food for winter at bottom of their pond, or swim out under the ice to harvest underwater plants.

After a few years, when beavers have eaten most of the food and felled the closest trees around their dam, the colony will begin looking for a new home. Once abandoned, the beaver’s dam quickly deteriorates and the pond recedes, revealing a new wetland or meadow covered with rich, newly-fertilized soil where plants will quickly grow.

Did you know?

  • A beaver’s front teeth are very strong, and are sharpened by their chewing.
  • Beavers have bad eyesight, but a strong sense of smell and very good hearing. They do most of their construction work at night.
A beaver chews on saplings at the Mendenhall Glacier Viewing Center in Alaska. USDA Forest Service photo.
  • A beaver has furry paws on their front legs that are good at grabbing and holding building materials, and webbed toes on their back feet that are excellent for swimming.
  • Beavers warn each other of danger by slapping their wide tails against the water.
  • A beaver’s tail also helps them balance when carrying building materials, and steer themselves while swimming.
  • A beaver can hold its breath while underwater for up to 15 minutes.
  • Beavers’ building benefits the environment in many ways, including protecting endangered salmon and their habitat. Young salmon and trout find protection from predators in the complex currents and mazes of logs and branches surrounding beaver lodges and dams. Debris piles leftover from former beaver dams and lodges also protects the streams and creeks running through them from erosion.

Education resources:

Video, info and fact sheets:

Activities:


Source information: Forest Features highlight a new Pacific Northwest species (or sometimes, a family, order, kingdom, or genus) each month as part of the USDA Forest Service – Pacific Northwest Region’s regional youth engagement strategy.

If you’d like fact sheets, activities, or links to other educational resources about this topic – and for information about other ways the Forest Service can help incorporate environmental education and forest science in your Pacific Northwest classroom – email YourNorthwestForests@fs.fed.us.