Sustainability

Appreciate our furry ecosystem engineers

by Malcolm Kenton   •   March 11, 2013 2:48 pm

The DC area's beaver population has boomed in the past 20 years, and that's a great thing.

Beaver at Kenilworth Aquatic Gardens. Photo by Glyn Lowe Photoworks on Flickr.

It's a sign that our region's waterways, having suffered from decades of channelization, pollution, neglect and mismanagement, are starting to regain their ecological health, though much work remains to be done.

The industrious creatures' presence brings challenges when their work conflicts with human activity, but beavers, which biologists recognize as a keystone species, benefit the environment far more than many people realize.

There are many tools for coexisting with beavers and the other creatures their ponds attract, even in highly developed areas. The alternatives to coexistence tend to be inhumane, ineffectual and shortsighted.

The beaver, North America's largest native semiaquatic rodent, is often misunderstood and greatly under-appreciated. Yes, they do cut down trees and build dams that can flood parts of low-lying areas. But these activities bring a host of benefits for ecosystem health, biodiversity, other wildlife, and for water quality, erosion abatement, flood control, and even act as carbon sinks that take greenhouse gases out of the atmosphere.

Beavers abounded throughout North America prior to Europeans' arrival, and they were almost certainly abundant in our region, which boasted a great deal of marshland and a plethora of streams, some of which humans have built over or removed by human activity.

Beavers were hunted and trapped nearly to extinction by the turn of the 20th century, mainly for their fur. But one of the greatest success stories of the modern wildlife conservation ethic has seen the industrious rodents return to almost all of their historic range.

At the same time, efforts to allow native vegetation to grow along stream beds in urban and suburban areas to improve water quality has recreated attractive habitat for beavers. They have come to inhabit creeks and streams in urban and suburban areas across the US, where their activity has at times come into conflict with human desires.

Sign at Lake Artemesia in College Park. Photos by the author.

Nature's engineers now inhabit a number of waterways in our region, including Rock Creek, the Anacostia River and its tributaries (including Kenilworth Aquatic Gardens), Lake Artemesia in College Park, Roaches Run Pond in Arlington, and Lake Accotink in Springfield, just to name a few.

Stories of trouble stemming from beavers' handiwork have appeared with regularity in the Washington-area press in the past two decades. In some cases, such as when beavers felled some of the beloved cherry trees along the Tidal Basin in 1999, trapping and removal of the beavers is unavoidable (luckily, this particular colony was able to be relocated to a more favorable site in the area). But in others, humans have harassed or killed beavers and destroyed their dams for no good reason.

One such incident occurred in Hyattsville's Magruder Park (located, aptly enough, on Beaver Dam Park Road) in the spring of 2011. One or more beavers dammed up the small stream draining into the Northwest Branch of the Anacostia on the park's west end, creating a small pond, which also covered a small portion of the adjacent parking lot. This did not seem to present a significant inconvenience to park visitors, and park managers cut a hole in the dam in attempt to let some water drain while retaining the beavers. But sadly, the dam was found broken up one morning in April along with the carcass of its architect.

This beaver-created pond still stands at Magruder Park in Hyattsville. Photo by the author.

The trouble with exterminating beavers is that, as long as the habitat in question remains reasonably healthy, other beavers are likely to come to the same spot. Each year, beaver parents evict their one or two-year-old offspring from their lodge and they go in search of new homes. And no matter how many times humans destroy a beaver dam, beavers will keep rebuilding it.

So in places like Magruder Park, unless park managers were to remove all the vegetation around the stream and keep the area clear—which would be undesirable—to keep removing beavers each time they show up is to fight a losing, and ecologically foolish, battle.

It is far better for people to learn to coexist with their wild neighbors. In cases where flooding or high water levels are the issue, several devices exist to regulate water levels while leaving beaver dams intact and tricking beavers so that they do not seek to raise the water level.

Trees can be protected by wrapping their trunks in cylindrical cages, and a low fence will keep beavers away from a particular group of trees. Beavers tend to fell fast-growing tree species that have little commercial value, and this culling makes room for more, bushier growth the next spring, restoring a more diverse mix of flora to the wetland area over time. Beavers largely subsist on seaweed, clover, and land and aquatic plants other than trees.

Beaver ponds attract and sustain other wetland-dependent creatures—such as turtles, herons, otters, ducks, and many types of birds and fish. They also do a good job of retaining stormwater runoff, allowing pollutants to settle out before the water moves downstream. Beavers have also become a unique cultural asset to cities and towns: they are local celebrities in places like the Bronx River in New York and Chicago's Lincoln Park.

But perhaps the best-known "downtown beaver" success story comes from Martinez, California, a Bay Area city that rehabilitated part of the creek that runs through the center of town. When a beaver colony established itself there in 2008, the local government threatened to have them removed. But citizens' organization Worth a Dam rose to the creatures' defense, and the city has come to celebrate its newfound furry, feathered and finned denizens, which have even attracted visitors from around the country and overseas (many of whom arrive on Amtrak).

The challenge of coming to terms with beavers in urban areas is a microcosm for the necessary large-scale work of reconciling human needs and desires with the natural systems that sustain all life. In our region, we can and should find ways to allow, and even help, beavers to do what they do best: maintain healthy wetlands. In return, we will enjoy cleaner water, better regulated stream flows, less severe flash floods, and the chance to interact with a wide array of wild creatures.

Malcolm Kenton lives in the DC neighborhood of Bloomingdale. Hailing from Greensboro, NC and a graduate of Guilford College, he is Director of Outreach and Engagement for the National Association of Railroad Passengers, where he blogs about national transportation issues. The views on GGW are his own and not necessarily those of NARP.