The two most common conflicts between humans and beavers are the flooding that results from dam building and the damage or destruction of trees. Flooding can become a crisis if beaver dams are not monitored, and the area is inundated by unusually heavy rains. Trees cut by beavers may strike utility lines, or the trees themselves may be prized specimens—as happened in 1999, when beavers felled some of Washington, D.C.'s beloved cherry trees.
Most of the trees used by beavers are felled within 100 feet of a body of water; the trees are usually two to six inches in diameter, but can reach 24 inches. Often, beavers partially or completely "girdle" trees, removing the bark but leaving the trees standing.
The key to living with beavers is appreciating the important role they play in establishing and maintaining wetlands, which in turn provide critical environmental functions. The beaver's handiwork can have far-reaching positive effects. Beaver impoundments provide rich habitat for a great variety of species, including plants, waterfowl, songbirds, amphibians, fish, insects, and mammals. Dams may also improve water quality by acting as a settling basin, and provide excellent flood control by slowing water movement.
Tree Protection
If your wooded property is adjacent to an area populated by beavers or located near water, your aquatic neighbors will likely pay a visit in the autumn and early spring. This may not be a problem for many people. But if you have small ornamental or valuable specimen trees that need protection from beavers, tree guards are an effective solution.
You can wrap small trees with simple cylinders of galvanized, welded wire, placed 6–12 inches out from the trunk and standing about three feet high. Chicken wire or hardware cloth (1/4- to 1/2-inch mesh) will also work, but the heavier galvanized wire will hold up better. Cylinders on larger trees may require staking, and mulching within the cylinders will prevent weed growth. For seedling trees, corrugated plastic drainpipes provide low-cost, easy-to-install protection. Just slit the pipes to allow room for growth, then place them around the trees.
Since beavers are not good climbers, a three- to four-foot fence can also be a permanent deterrent. This may be the best option when trees that need protection are grouped together. Try fencing off just the water side first, and then extend the fence if the beavers start to find their way around it.
Baffling a Beaver
While beavers are superb engineers, they're no match for humans. Where flooding is an issue, you can install "bafflers" or "levelers" that control the water level without disturbing the beavers.
Beavers are thought to be stimulated to repair breaches in their dams by the sound, feel, and sight of running water—a logical response as a draining pond can quickly leave them exposed to predators. Beaver "bafflers" work by dispersing the flow in such a way that the beavers are not stirred to plug them up. Bafflers have many different designs, and can be constructed of plastic or metal pipe, wooden troughs, or metal mesh fencing formed into culverts.
The Beaver Deceiver™ is another effective device. Deceivers are trapezoid-shaped fences built around points of vulnerability like easily plugged culvert openings. These fences extend outward to create an area large enough to discourage damming and to keep beavers away from the moving water that triggers dam building. The design and installation of beaver bafflers and deceivers are sufficiently complex that technical experience from professionals is recommended. It's also important to be aware of local, state, and federal regulations when planning to install these devices.
