Can We Coexist with Beavers?

Ed Murtagh - May 19, 2012

As we green our communities, wildlife is slowly returning. As wildlife returns, we need to find ways to coexist with these animals. One creature that has returned is the beaver. Beavers are amazing creatures that provide valuable ecological services. Beavers, like people, build structures in order to modify their habitat. Beavers frequently build dams in streams to create ponds and wetlands, which provide valuable habitat not only for the beavers, but also for many other creatures. Beaver dams also help clean our streams. Excessive sediment, one of the major problems facing our local streams and the Chesapeake Bay, has an opportunity to settle out behind the beaver dams.

While beavers are important, they can create problems in our built-out urban environments. We have watched in alarm as ecologically valuable reforestation sites along streams (riparian zones) are quickly destroyed as beavers cut down newly planted trees. This, of course, is not vandalism. The cambium layer of trees (located just beneath the bark) is an important source of food for beavers in the fall and winter. In a healthy ecosystem, the loss of these trees would be part of a natural forest succession. However, due to the onslaught of invasive exotic plants and the high concentrations of deer in the lower portions of Montgomery County, the forest successions have been disrupted. As a result, the beavers’ feeding practices are negatively affecting their environment. Beavers can also create serious and expensive problems in stormwater ponds built to protect downstream communities. Beaver dams can also flood low lying property.

Recently Rob Gibbs, the County Parks Natural Resource Manager, gave an interesting presentation to Friends of Sligo Creek on how Montgomery County is working to balance the needs of humans with the needs of beavers and many other creatures. Once nearly extinct, beavers have returned to all our county’s stream valleys including Sligo Creek, the Northwest Branch and Rock Creek. Rob noted that the park staffs work to accommodate beavers. Significant trees that are in danger of being cut down by beavers can be protected with three foot high cages. Rob also showed a cleverly designed drainage system that goes through a beaver dam and allows parks staff to control the water level behind the dams, thus preventing flooding in nearby low lying areas. Much of Rob’s effort goes to educating Parks staff about how to coexist with beavers.

Sometimes beavers will move into stormwater ponds. These ponds are engineered structures designed to capture and slowly release rain water. Because these ponds control flooding, thereby affecting the safety of nearby areas, they must be operated and maintained according to county regulations. The Parks staffs are working to make these ponds “beaver resistant” by using fencing around the drainage pipes. Beavers will instinctively block a stormwater pond drain pipe, effectively disabling one of the pond’s main functions, storing stormwater runoff. Beavers are territorial, and it can be difficult to relocate them because there are no streams in the county that do not already have beavers living in them. In these cases, beavers are captured and euthanized in a humane manner.

The problems with beavers coexisting with humans come down to how we have modified land to meet our needs. All too often, decisions on if and how we developed land in the past did not take into account the impacts on our natural resources. As we work to green our communities, we will need to be smarter in our land development and become better stewards of our properties. By taking meaningfulpersonal action, we can successfully coexist with beavers and other wildlife. For example, if homeowners successfully manage stormwater on their properties, we will be less dependent on the stormwater ponds, eliminating on source of conflict between us and the beavers.