Beavers are known as “ecosystem engineers”, or “nature’s architects”, because their dam-building work has such a huge effect on the habitats around them.

A North American beaver (Castor canadensis) builds a dam (photo by Chase Dekker).

Beavers critically influence the ecosystems of the Pacific Northwest and play a fundamental role in creating and maintaining a diversity of flora and fauna associated with Oregon’s streams, rivers, and wetlands. Prior to European arrival in North America, Oregon’s streams and rivers may have harbored an estimated one million North American beaver. Unfortunately, historic trapping efforts to create a “fur desert” in Oregon resulted in dramatic declines of the species and trapping continues to this day.

Cascadia Wildlands is currently attempting to prohibit commercial and recreational trapping of beavers on federal lands through a petitioning effort to Oregon’s Fish and Wildlife Commission.

Beaver Fast Facts:

  • they are a primarily nocturnal, semi-aquatic rodent
  • they are the second-largest rodent in the world after the capybara
  • beaver incisors (front teeth) never stop growing, withstanding the constant wear of chewing and cutting down trees
  • their incisors contain so much iron that the enamel is bright orange
  • while slow on land, they are good swimmers and can stay under water for as long as 15 minutes
  • they slap the water with their broad tail to alert other beavers to danger
  • they live up to 24 years of age in the wild

What do beavers use to build their dams? Beavers build their dams out of trees and branches that they cut using their strong front teeth. They also use grass, rocks, and mud.

Do beavers live in a beaver dam? Nope! Beavers build dams so that they have a safe pond where they can build their beaver lodge (den). A beaver lodge is built out of twigs, sticks, rocks, and mud, and has an underwater entrance. Inside their lodge, beavers have a safe place to sleep, raise their offspring, stay warm in winter, and hide from predators.

Beaver Benefits: Why you should give a dam

Relationship to Healthy Rivers, Salmon and Other Animals

When beavers build a dam, they create a pond behind it. By creating ponds, beaver dams enhance over-wintering habitat that can shelter young salmon from swift, high water flow events. Studies conducted in streams along the Oregon coast suggest that the winter survival of juvenile Coho salmon, which can be swept downstream by fast flowing winter streams, depends on adequate slow-water habitat. The readily available food and protective environment in beaver ponds lead to increased salmon growth and survival. Michael Pollack of the National Oceanographic and Atmospheric Administration (NOAA) has studied the relationship between beavers and juvenile salmon for over a decade (Pollack et al. 2004), and his research also supports that beaver ponds benefit the river ecosystem as a whole.

Riparian = refers to the areas of land located along the banks of rivers or streams (image source: Colorado Riparian Association).

Beavers shape and maintain healthy riparian habitat (see illustration at right). Beaver ponds increase the surface area of water several hundred times; this increased water supply increases vegetation growth by increasing the amount of groundwater for use by riparian plants and wetland areas. In turn, positively influencing the diversity and survival of many other species of animals and insects. Deep root systems from these plants maintain bank structure and combat erosion. While the trees and plants themselves provide shade needed to keep water cool and fish populations thriving.

Rancher’s Best Friend

As the planet warms and Earth’s climate changes, water shortages — especially in the state of California — are increasing. In response to this growing crisis, the Scott River Watershed Council (part of the Klamath River system) has been working with U.S. Fish and Wildlife Services (USFWS) and the California Department of Fish and Wildlife (CDFW) to encourage beavers to occupy the state. These ongoing efforts have shown that wells behind beaver dams recharge much faster than those on land without them, and beaver ponds build up soil and nutrients that helps to prevent floods and drought as well as feed the growth of diverse habitat. Additionally, beaver ponds and dams act as a giant water filter, resulting in cleaner water downstream. This all translates into money saved for ranchers and farmers. For these reasons, more and more ranchers are now seeing the benefits of beavers, and actively work to support beavers with riparian habitat planting.

Climate Champions

Not only do beavers grow the water table in an area, locking precious rainfall into the land, but beaver ponds also function as a major store of carbon in the form of settled organic matter. One 2013 study found that beaver complexes on a system of 27 streams within Rocky Mountain National Park at one point stored more than 2.6 million megagrams of carbon—an amount equivalent to the carbon stored by 37,000 acres of typical forest.

Diagram of effect on water table levels for a “no beaver stream” vs. “beaver dam stream” (graphic by of the American Geosciences Institute).

Beavers Are Essential

Beavers are critical to healthy ecosystems. Their dam building improves water quality and provides homes for countless species. This remarkable ability to transform their environment makes them an important ally in the fight against climate change and makes our forests and communities more resilient in the face of wildfire. Despite the significant ecological benefits provided by this species, the Oregon Department of Fish and Wildlife still permits widespread hunting and trapping of beavers.

This is why Cascadia Wildlands and dozens of other organizations have requested Oregon’s Fish and Wildlife Commission end the hunting and trapping of beavers and instead create practices that align with our state’s already established aquatic restoration efforts.

Across Oregon, federal agencies, state land managers, private industries, utilities, conservation organizations, watershed counsels and others have spent enormous amounts of time and resources on aquatic habitat restoration to improve water flows, watershed conditions, and aid in aquatic species recovery, which are all outcomes provided by beavers at no cost. The state resources used to achieve these ongoing efforts are greatly enhanced by the presence of active beaver colonies, and are therefore significantly hindered by the hunting and trapping of beavers.

Beaver kit swimming (photo courtesy of Cheryl Reynolds, Worth a Dam,