National Parks Traveler

Under The Willows: Beavers Partner With National Parks For Landscape Restoration

By Patrick Cone

For centuries beavers have been seen as nothing but pests. They inundate fields, plug culverts, flood roads, and chew down forests. They’ve stood in the way of progress. These rodents were hunted for their fur, their meat, and just generally extirpated from North America as Europeans terraformed the country for agriculture and settlement. In 1929, naturalist Ernest Thompson Seton guesstimated that there were at least 60 million beaver in North America, but by the end of the 19th century there were only about 100,000 remaining.

But now beavers are recognized as key to helping restore wetlands, replenish aquifers, and provide habitats in the National Park System. With a little help, nurturing and money, they’ve been successfully combating climate change, one twig at a time, across the nation.

Properly managed, these large rodents are coming back, from Acadia to Yellowstone, Voyageurs to Rocky Mountain, and in many other national parks. Beavers are opportunistic and resilient, reshaping the landscape from the tropics to the subarctic to the high mountains. Left to themselves, they can repair deep gullies cut by overgrazing, flood meadows to encourage willow growth, and provide habitats to dozens of other species. Their ponds not only hold back the spring snowmelt during an era of drought and climate change, but also act as firebreaks and, in general, repair an ecosystem back to its original state. From scientists to ranchers to anglers to hunters, beavers are now seen as beneficial in many areas. It’s thought they might save the West Coast salmon as well, as the fish easily bypass dams.

In some respects the Beaver is the most notable animal in the West. It was the search for Beaver skins that led adventurers to explore the Rocky Mountains, and to open up the whole northwest of the United States and Canada. It is the Beaver to-day that is the chief incentive to poachers in the Park, but above all the Beaver is the animal that most manifests its intelligence by its works, forestalls man in much of his best construction, and amazes us by the well-considered labour of its hands. -- Ernest Thompson Seton, Wild Animals At Home

They are a keystone species.

They can still be pests of course, but as humans are nominally smarter than beavers, they can be controlled. Acadia National Park, for instance, reintroduced one beaver on Mount Desert Island in the autumn of 1921. While it didn’t survive, three others did the next spring, and in just a few years there were dozens of animals, plugging culverts and flooding roads. There were so many, in fact, that they were regulated and many eliminated. Today, they are actively managed by park rangers to prevent flooding and damage to timber.

Meanwhile, in Rocky Mountain National Park in Colorado beavers have been encouraged to return to the headwaters of the Colorado River, but only after the willows were also allowed to grow back, protected from hungry moose and elk by fenced exclosures. Park scientists realize that “if you build it, they will come,” especially if they have a food source and safe place to live.

In Yellowstone National Park, 129 beavers were reintroduced north of the park between 1986 and 1999, and soon settled along Slough Creek. By 1995, elk herds had overpopulated and were chowing down young willows and aspens, leaving nothing for the beavers to eat, and the rodents moved out. But, as wolves were returned that year, the carnivores soon thinned the elk herds and the willows grew along the stream banks again, attracting the beavers back once again. However, the large herds of bison have also started to reduce the willows once again.  

Beavers are abundant in Voyageurs National Park in northern Minnesota, where there are an estimated 3,000 of them. Between 1940 and the 1980s they made a comeback as new aspen groves sprang up in the wake of logging and wildfire, and they might be instrumental in the resurgence of the moose population. Along Namakan Lake there is on a dam that is more than 15 feet tall and 200 feet long. They’re everywhere. It’s beaver heaven.

At Bandelier National Monument in New Mexico, beaver reintroduction has been successful too, holding back water in this high desert, recreating wetlands, and even acting as firebreaks. All this in just three years, when three beavers were reintroduced along the Rio De Los Frijoles.

Elsewhere in the park system scientists are encouraging beavers to homestead on their creeks by building what are known as "beaver dam analogs" (BDAs). These structures mimic beaver dams, holding back water, flooding terrain and nurturing trees and willows as a food source. A few of these were just installed along Strawberry Creek on the north side of Great Basin National Park in Nevada. Similar actions are being taken along the Mancos River in Mesa Verde National Park.

Beavers are incredibly adapted, and don’t ask for much, just a food source, perennial stream and wood to build dams. They live in twig lodges with underwater entries, for protection from predators, where they’ll produce one to two kits per year. Their brown-stained teeth absorb iron to make them hard enough to chew through wood. They do what they do, and they do it well. With proper management in a warming climate, they just might be the answer to rewater the parks' landscape.  

Watch the Traveler in the coming weeks and months for stories from the parks that profile the work these ecological engineers are performing. 

Editor's note: In the following video, it should have noted that the moose were introduced into Colorado by the state Parks and Wildlife Department. It was not a recovery program.