As City Wildlife frequently tells people, the District of Columbia is home to a surprising number of wild animals. But only a select few of these animals are ecosystem engineers; among animals, beaver have an essential monopoly on that activity.
We humans engineer our environment, of course, although it often seems as much to our detriment as benefit. After us, no better example of engineering exists in the natural world than the North American beaver, Castor canadensis. Millions of years before humans began to dig canals to irrigate fields, beaver were building canals to safely reach sources of food or to transport supplies for their dams and lodges, achievements in construction that even we would do well to emulate.
Before European colonization, beaver probably had impoundments along every stream tributary throughout their considerable range, which covers nearly all of North America from the Canadian tundra to the deserts of the American southwest. Sadly, the species was nearly extirpated due to the trade in its fur, which was prized in Europe for (among other things) men’s top hats. It has taken more than a hundred years, but beaver are now making a comeback, returning to the streams they once occupied throughout North America, including in Washington, D.C.
This is a good thing. By creating impoundments, beaver perform a variety of ecosystem services: slowing down runoff and decreasing water turbidity after storms, controlling floods, and creating wetlands that provide habitat for a multitude of other species. That makes the beaver a keystone species, one upon whom many other species depend. In the West, beaver ponds can help mitigate drought conditions and provide water for livestock, as well as wildlife, during scarcity. Even the beaver-built homes and lodges provide habitat for insects, aquatic invertebrates, and small mammals such as mice and muskrats. Numerous studies now demonstrate these and other benefits of the beavers’ recolonization of the riparian areas from which they were long missing.
But not every species appreciates beavers’ alterations of the environment. People often wish to save trees that beaver fell, and beaver impoundments can fill the floodplain around streams where we shouldn’t —but often do —place infrastructure such as rail and sewer lines and even buildings.
Happily, a growing number of individuals and organizations who are dedicated to promoting understanding and coexistence with beaver have come up with simple ways to deal with these inconveniences. Beaver are great engineers, but so are we. We can build flow devices that prevent or control flooding, use wire caging or fencing to protect important trees, and work with —rather than against — this species to improve habitat for wildlife, as well as for ourselves.
Perhaps one day we will even have the foresight to work with beaver and the free services they provide, allowing impoundments upstream on a scale that mitigates the pollution and degradation of aquatic systems downstream. After their long absence, the beavers are ready to get back to work. You can see them already hard at it — busy and eager —at the National Arboretum or Kenilworth Aquatic Gardens, among other spots.
Here are a few organizations that are dedicated to beaver-human coexistence:
Beavers, Wetlands and Wildlife (BWW). Dolgeville, NY. Educational and outreach materials as well as support services since 1985. https://www.beaversww.org/
Worth a Dam. Martinez, CA. Advocacy, outreach and support services built around a fascinating story of how one community went from wishing to exterminate beaver to holding an annual festival to honor them. https://www.martinezbeavers.org/
Beaver Deceivers International. Grafton, VT. The father of flow devices that keep beaver ponds from flooding, Skip Lisle, revolutionized how we resolve conflict with beaver. https://beaverdeceivers.com/
Beaver Institute. Southampton, MA. Outreach and educational materials. https://www.beaverinstitute.org/
Wildlife 2000 Guidebook. The amazing story of Sherri Tippie who moved the needle in Denver, CO from trapping and killing to trapping and relocating in the water-starved West. https://www.beaverinstitute.org/wp-content/uploads/2017/08/Wildlife2000Guidebook.pdf
For the kids, the South Umpqua Rural Community Partnership’s Beaver Advocacy Committee has a fun and informative resource to share. https://umpquawatersheds.org/wp-content/uploads/Beavers.pdf