AS SEEN IN Community Assets, Written by Industry Expert Gavin Ferris, Ecologist, SOLitude Lake Management
The North American Beaver, Castor canadensis, is a truly remarkable animal. It is common knowledge that beavers build dams, and that the water held back by these dams provides them with protection from predators. What few people know is that their instinct to build these dams approaches the point of outright neurosis. When a beaver sees or hears water flowing, he is obsessed by a desire to make it not flow.
In the wild, this little quirk is highly admirable. Beaver ponds provide vital habitat for waterfowl, amphibians, reptiles, and numerous wetland plant species. As beavers were once nearly wiped out across the continent this valuable ecosystem service became all too rare, and many species suffered. Beavers are now becoming common again, and thankfully these key wetland habitats are reappearing throughout their range.
In a stormwater pond, however, this trait becomes a major character flaw. These ponds are carefully designed to allow water to flow at a specific rate to allow the ponds to be maintained at the correct water level. Any obstruction to the pond’s outflow hinders this operation, resulting in improper stormwater discharge. If allowed to persist, the inevitable flooding can lead to property damage.
In addition to using logs and sticks to build their dams, beavers also rely on woody vegetation for their primary food source. Their diet consists almost entirely of hardwood tree bark. Even after they have built their dam and lodge, beavers must continue to cut down trees in order to eat. If necessary, they will cut trees a considerable distance from the water and drag them into the pond to procure this food source. The resulting damage can be both unsightly and very expensive.
Early in its construction, a beaver dam is little more than a pile of sticks and mud. Removing it takes just a few minutes with a rake and shovel. Once beavers have identified a desirable habitat, however, they will continue to rebuild the dam. And if it is not cleared away regularly, it will grow to a more substantial structure. These early construction efforts are usually the work of one or two animals at most, and removing them before they establish a family group is much easier than extricating an entire beaver colony.
A dam that has been allowed to develop for some period of time is significantly more difficult to remove. The interlocking logs and branches are more than can be easily removed by hand tools, and heavy equipment is often required. Breaching a dam that has been established and maintained for several years may even require the use of a significant quantity of high explosives. Such endeavors require careful planning, and may also necessitate draining the pond before execution, the involvement of engineers, special permitting, and a tremendous amount of manpower. These factors make the removal of a large beaver dam costly, and best avoided if possible.
Even if a dam is removed, it is likely to have been built and maintained by a multi-generational family group of up to a dozen animals. Beavers can be remarkably stubborn and may begin rebuilding the structure immediately. Successful beaver dam mitigation often requires trapping the offending animals as well. For both regulatory and practical reasons, the removal of beavers is almost always carried out through lethal methods.
Because reacting to beaver damage is both costly to the landowner and often deadly for the beavers, it is best for all involved to discourage them from settling on your property in the first place. While no method can ever be certain to discourage beavers due to the inherent unpredictability of wild animals, a few simple measures can make your waterbody less attractive to any beavers that may be seeking to take up residence.
The first step in beaver prevention is to eliminate potential sources of food and building material. Trees and woody shrubs are wonderful additions to your landscaping, but they do not belong on or near the banks of your pond. Black willow saplings that sprout along the shoreline should be treated and removed regularly, as should any other woody vegetation near the water.
Once any weed trees have been removed, any remaining trees should be protected. A mixture of sand and exterior latex paint applied to the trunk and any exposed roots will make the bark unattractive to any beavers looking for a meal. Apparently, they don’t like the sensation of chewing sand any more than we do.
Most importantly, monitoring for animal damage should be an element of regular pond maintenance. In addition to watching for groundhog burrows and muskrat runs, any sign of beaver activity in or around your pond should be noted and acted upon immediately. Obvious beaver signs include chewed tree stumps and sticks with the bark chewed off. A beaver’s work is easily identified by the tooth marks left by their chewing, which leaves the wood looking as though it were carved with a chisel.
If beaver activity is detected, it is important to begin action quickly. Any unwanted woody vegetation should be removed immediately, while the desired trees should be protected and preferably surrounded by wire fencing. And, all debris that looks like the beginnings of a beaver dam should be cleared immediately. If you are lucky, the beavers will be discouraged and move on. If settlement attempts continue, a licensed wildlife control professional should be contacted to remove the beavers while their numbers are few.
Spending time and money on beaver mitigation before you have a beaver problem may be a bitter pill to swallow. But keep in mind the cost of delaying these actions. Dealing with a wildlife problem is always a touchy situation. Nobody wishes to harm animals unnecessarily, which often delays action. The longer the problem persists, the more expensive and unpalatable the solution. Therefore, the old saying remains true: an ounce of prevention is worth a pound of cure.
Contact the experts at 888-480-LAKE (5253) for all of your lake, pond and fisheries management needs.
Gavin Ferris is an Ecologist with SOLitude Lake Management. Since 1998, SOLitude Lake Management has been committed to providing full service lake and pond management services that improve water quality, preserve natural resources, and reduce our environmental footprint. Services are available throughout the Eastern United States. Fisheries management consulting and aquatic products are available nationwide. Learn more about SOLitude Lake Management and purchase products at www.solitudelakemanagement.com.