Water Level Control
In most cases, water level control can provide the best technique for beaver pond management in situations where the removal of the beavers is not desired or practical. Several types of drains proven successful in controlling water levels include aluminum, PVC, and wood and steel. All of these drains have one thing in common, small drain holes, which the beavers are usually unable to obstruct.
The three-log drain (Figure 2), made of wood and steel, is the most economical. It is constructed with three logs, nails, short pieces of wood and two pieces of tin or scrap metal. The disadvantage of the three-log drain is its weight, which makes it difficult to handle. Due to this, you may want to use a 6 to 10 inch diameter aluminum irrigation pipe or PVC pipe with three rows of 3/4 inch diameter holes spaced six inches apart along the bottom of the pipe (Figure 3). In addition to being lightweight, these drains are easy to construct, install, and remove, when the area is ready to be flooded again.
High rainfall and high stream flow may prevent drainage unless several drains are installed in a beaver dam. After three-log drains or pipe drains are installed, they should be checked at least monthly and maintained as required to insure proper operation.
Pipe Drain Installation
- Break the dam at the existing channel in the form of a narrow, deep "V".
- Wait for the waterflow through the dam to lessen before beginning installation.
- Install the drain with the upstream end completely covered by water (the intake side), and at least one foot lower than the outlet end of the drain. The outlet end should be at the desired water level of the pond. At least 10 feet of pipe should extend into the pond. Anchor the pipe on the upstream side with two metal stakes.
- Once the drain is installed, the beavers will repair the damage to the dam. The drain pipe, however, will maintain the desired water level.
Figure 2. Water levels in beaver ponds can be managed to compliment land use practices through installation of log drains.
Figure 3. Aluminum and PVC pipe drains can be used to manage beaver pond water levels and are also lightweight and easy to install.
History and Purpose
The North Carolina Beaver Management Assistance Program (BMAP) was created by state legislative action in 1992 with the express purpose of helping manage ever-increasing problems caused by beaver on private and public lands. Because of practical and ecological considerations, the program is not designed to eradicate beaver populations. Rather it is designed to assist the North Carolina Dept. of Transportation (DOT), local governments, private landholders, and others address specific beaver damage problems.
The program is run by USDA Wildlife Services through a cooperative agreement with the North Carolina Wildlife Resources Commission. This program is a cost share program to aid landowners in participating counties with beaver problems; funding comes from state, county, federal, and private sources
Since 1992, the BMAP has grown from 4 participating counties in 1992-1993 to 45 participating counties in 2007-2008. Participating counties contribute $4,000 to the program, which help individuals residing in these counties obtain assistance with beaver damage by contacting their county Cooperative Extension or Soil and Water Conservation District office.
Figure 1. Counties in which BMAP personnel assisted private landowners with beaver conflicts during 2008.
To find out if your county is enrolled in BMAP and how to get services click here (PDF)
BMAP services specifically delivered to the DOT are now available in all 100 counties in North Carolina.
Figure 2. Counties in which BMAP personnel assisted DOT with beaver conflicts during 2008.
BMAP Damage Economics
In FY 2008, wildlife specialists and cooperators reported that BMAP services prevented impending loss or repair expenditures of an estimated $4.57 million in timber and other agricultural resources, roads and bridges, railroad trestles, dams and ditches, city and county sewer systems and water treatment facilities, landscape plantings, and other resources such as homes, airport runways, and golf courses.
Comparing BMAP expenditures to savings, the estimated cost-benefit ratio was a favorable 1 to 4.06. In other words, for every $1.00 spent, $4.06 in resources was saved.
The cost-benefit ratio does not measure the benefits of educational activities such as training individuals to take care of their own beaver damage problems. State revenue generated from taxes on timber sales are not included in these projected future savings estimates.
Although beaver ponds are naturally beneficial waterfowl habitat, in some cases they may be improved by management. New ponds with live trees may be converted into green-tree reservoirs to attract ducks, with minimal loss to timber production. Acorns are a preferred food of many ducks, and oak trees can be maintained by draining the beaver pond during the growing season from March through September. Remove the drain during the dormant season (October-February) allowing the beavers to repair the dam. Then the resulting flooded area will provide resting and feeding areas for waterfowl.
Old beaver ponds with dead trees and plenty of sunlight reaching the water surface can be developed into attractive waterfowl feeding areas by draining the pond during the growing season. One method is to drain the pond and rely on natural vegetation to grow and provide waterfowl food. Another method is to drain the pond and plant Japanese millet. Whether relying on natural vegetation growth or millet plantings to produce waterfowl food, the drain should be set to leave water on 1/3 to 1/2 of the pond area. If the pond is completely drained, the beavers may relocate.
- Broadcast Japanese millet seed on the soft mud at the rate of 25 pounds per acre. Millet should be planted by July 15 in the mountains to as late as August 14, on the coast. Additional land preparation is not needed, and fertilizer should not be necessary for the first two years.
- Drains should be checked weekly to insure proper operation.
- Remove the drains after the plants turn yellow and the seeds are mature. Seed maturity usually requires 45 to 50 days. Once the drains are removed, beavers will repair the dam and the millet will be flooded for waterfowl.
- Drain the pond each summer to allow the millet seed to germinate and grow. In many ponds the original seeding of millet will provide enough hard seed for two to three years before re-seeding becomes necessary.
Wood Duck Nest Boxes
In addition to providing attractive waterfowl feeding areas, beaver ponds provide excellent nesting and brood rearing areas for wood ducks. Initially, the use of wood duck nesting boxes will increase the number of wood ducks reared in beaver ponds. Yearly maintenance of wood duck nest boxes is essential to insure maximum use. For this reason, do not erect more nest boxes than you will be able to maintain annually. As the breeding wood duck population increases additional boxes may be erected up to a maximum of 7 boxes per acre.
Plans for an artificial wood duck house are shown in detail in Figure 4. Pay special attention to the entrance hole measurements, which are designed to keep out larger predators such as raccoons. For best results, use rough cypress lumber to build the box. However, you can use one-half inch exterior or marine plywood, or any other suitable lumber treated with a preservative such as copper napthanate or pentachlorophenol. If materials with a smooth inner surface are used, a four inch wide strip of 1/4 inch hardware cloth must be attached to the inside front wall from the floor to the exit hole, to enable the ducklings to climb out of the box. Boxes should be erected in early winter to insure maximum use, because wood ducks start selecting nest sites as early as January.
Figure 4. Erection of wood duck nest boxes will increase the attractiveness of beaver ponds to this native waterfowl species.
All houses should be securely fastened to some stable structure such as a post or tree in or near the water. They may be erected with no tilt or a slight forward tilt. Never tilt a box backward, since this prevents the ducklings from being able to climb the wall and leave the nest. All cracks or holes, except the exit hole and several drainage holes in the bottom, should be sealed or covered. Place boxes in relatively open areas with the entrance holes pointing either upstream or downstream so that that they may be readily found by the ducks. Do not shield the entrance with branches since wood ducks fly directly into the box and do not need to perch before entering.
Many wood duck boxes have become "death traps" because they were poorly constructed or not made predator-proof. Be careful to select locations that do not offer overhanging branches or other pathways for depredating raccoons, snakes, or other hungry animals. Always use the predator shield explained in Figure 4, or install the boxes on a smooth pipe. Boxes should be placed a minimum of three feet above the water or, when placed over land, at least ten feet above the ground.
Yearly maintenance will be needed prior to each nesting season. At this time be sure to remove all useless debris, replace or add wood shavings, check the box stability, and replace all broken hardware or rotten boards.