Beavers (Castor canadensis) are in all areas of Nova Scotia. These aquatic rodents live in family units, typically consisting of two adults, 2-3 three yearlings, and 3-4 young of the year. The species can provide great benefits to the environment and to the ecosystems in which they are found. Their dams can stabilize stream flows and can trap sediments in the watercourse, and the wetland created through the dam construction can be used by many wildlife species as a productive breeding and foraging habitat. However, beaver dams near agricultural fields can often result in flooding and can ultimately lead to the loss of valuable crops or fields access. Signs of beaver include plugged culverts and a visual loss of trees with nothing left but wood chips and pointed stumps.
Note. A Nuisance Wildlife Permit is required to trap and/or dismantle a beaver dam, including unplugging a culvert. There are also restrictions in place surrounding the time of year in which beavers may be trapped and dams removed. Contact your local DNR office to learn more about these restrictions and to obtain the proper permit.
Diet and Lifecycle
Beavers are the largest rodent in North America, reaching over one meter in length and weighing up to 32 kilograms. They are vegetarian, feeding on plant materials, including aquatic plants, shrubs and trees. Beavers typically mate between January and March, and are one of the few monogamous species, meaning they mate for life. Females have one litter per year, with kits (baby beavers) being born between April and June. Within 24 hours of birth, the young can swim, and will explore beyond the beaver lodge within a few days. The young stay with their parents for about two years, after which, they leave to find a mate and build a new home elsewhere. Beavers can live to be 20 years old. Beaver populations were severely threatened in the past, primarily caused by unregulated hunting and trapping. However, due to wetland restoration and conservation efforts in recent years (e.g. fixed trapping seasons, bag limits and restrictions protecting dams and lodges), their numbers have increased dramatically.
Managing Nuisance Beavers
The following are methods of beaver control suggested by the Department of Natural Resources (DNR). However, as already mentioned, contact your local DNR office if beavers become a problem species on your property. Appropriate permits must be acquired before manipulating or changing a beaver’s habitat. Having a licensed trapper on the property during the regular fur harvest season will also help keep beaver numbers in check, by allowing them to trap as part of their quota for the season.
Electric Fences
A temporary electric fence can discourage beavers from repairing dams after deconstruction. Two wooden stakes can be driven on either side of a newly created opening. Fasten a plastic insulator to each post at least 46 cm (18 inches) above the water level. Run a tight horizontal wire such as 12-gauge soft iron between these two insulators. Place four wires, 10 cm (4 inches) apart across the opening and trim each to within five centimeters (2 inches) of the water’s surface, ensuring that the horizontal or vertical wires are not in contact with the ground, water, or any vegetation. Hook them to the ‘hot’ wire of the charger. Ground the fence with a three-foot (1 cm) metal rod near the dam break. Check the device regularly to ensure the system has not been obstructed by floating debris. Leave the fence up once the charger is removed as occasional “reminder periods” may be required. Twelve-volt electric fences are available at most farm supply outlets at prices ranging from $35.
Water-Level Control Devices
Water-level control pipes and boxes are used to control excessive flooding but do not require the removal of beavers. They are most suited to small ponds and wetlands. A permit is required install water-level control devices. A small breach is made in the dam allowing the installation of an unperforated pipe which extends a few feet downstream. A perforated pipe (3/4 inch (1.9 cm) holes) with its upstream end plugged, is staked out into the pond at varying distances depending upon the depth of the water, diameter of the pipe and size of the watershed. Two or more pipes extending out in a “fan” shape are often used. The perforated portion of pipe should extend out into three to four feet (0.9 to 1.2 m) of water to prevent beaver from plugging the pipe. The water level in the pond will stabilize with the top of the perforated portion of the pipe.
Water-level control devices can be constructed of wood, sewage pipe, corrugated drainage pipe, as well as old metal culverts.
Tree Protection
Beaver sometime cut down valuable ornamental trees near lakes or streams. This damage usually occurs at night. The best protection consists of encircling individual trees and shrubs with a securely fastened, stiff woven or webbed wire with a mesh no larger than two inches (about 5 cms). Beavers will also cut trees in winter from a raised snow surface so ensure that the height of the mesh extends about 1 m above the ground. Beavers prefer broad-leaved, ‘hardwood’ trees but may take softwoods if no preferable trees are available. In some circumstances a 30-inch (76 cm) woven wire or a low electric fence running along the entire shoreline has been used to protect the trees and shrubs of a group of residences or cottage owners.
Culvert Guard
In situations where a beaver ponds is acceptable or even desired, flooding can be controlled by using a culvert guard. In this case a six-foot (1.8 m) length of concrete reinforcing wire is rolled into a cylindrical shape slightly larger than the diameter of the pipe to be protected. It is then fitted over the upstream end of the culvert and a second rolled wire mesh is added to extend the cylinder’s length to 12 feet (3.6 m). The upstream end of the cylinder is pinched or wired shut. The device is held in place with metal stakes. Beaver will often construct a semicircular dam around this structure, however, the culvert will still work during flood conditions.
Culvert Protector / Cleaner
Clearing culverts can be made easier by constructing an easily cleared, removable grate. Place 3/4-inch (1.9 cm) rebar (concrete reinforcing bar) through two lengths of chain every 8” and weld them in place. Securely bolt the upper end of the loop to the top of the culvert (it helps if the end of the culvert was out on a slope when installed). Make sure the protector extends into the pond six feet (1.8 m) beyond the culvert. Run a tail chain from the upstream side of the cleaner to the bank. This device makes it easier for the beaver to build a dam, but by hooking the tail chain to a tractor or farm vehicle you can undo a whole night’s work in a few seconds! Often this will discourage them.
Trapping
Where action is required to remove beavers or beavers’ dams or to install any of the above-mentioned deterrent devices, the landowner must get in touch with their local DNR office, who can put them in touch with a Nuisance Wildlife Operator (NWO) if the landowner cannot do the work themselves. In an emergency situation (for example, serious flooding), DNR can take some action to alleviate the immediate problem.
Live trapping is a difficult, time-consuming and costly process and there are few available places to put beavers, making live trapping an uncommon solution to nuisance beavers. During the legal fur harvest season, licensed trappers can control or eliminate nuisance beaver colonies on farms. In certain circumstances, permits may be issued to shoot nuisance beavers. Public safety is always the prime consideration in such cases. To get more information about trapping and shootings nuisance beavers, contact your local Department of Natural Resources office (See “Additional Resources”).
Additional Resources
For more information about nuisance beavers, contact the local DNR office. You can get in touch with them by accessing the DNR website.