Identification of Damage

Muskrats damage ponds by burrowing into dams and banks to make dens, thus increasing the chance of seepage and erosion. Den openings are 4-6 inches in diameter and are usually near the surface, though in ponds with frequent water level fluctuations they may be in deeper water. In clear water, dens are usually visible, but in turbid water, they must be detected with hands, feet, or a pole. When ice appears, trails of bubbles and chewed vegetation will lead to active dens.

Beavers burrow into dams and banks, cut trees, and plug outlet tubes. Their work is conspicuous and they are extremely persistent. Bank dens are 12-18 inches in diameter and will be present whether a dammed lodge is present or not. In fall and winter, a pile of fresh cuttings will be evident near the lodge or main den.

Prevention of Damage

Muskrat damage is unlikely in ponds where the dam is sodded, ungrazed, and built to Natural Resources Conservation Service specifications. Hard clay should be used in construction to discourage burrowing. To control burrowing after it has begun, all muskrats in the pond should be trapped, and affected areas should be riprapped. Wire mesh or fencing can also be used, but these materials yield to corrosion after several years. If all muskrats are not removed, survivors will find a way to reopen their traditional burrows.

Beaver burrows are big enough to damage even well-built dams. Riprap will discourage initial burrowing, but all beaver must be trapped if burrows are to be sealed. If burrows break through the surface of the dam, the opening should be collapsed as far back as possible and filled with clay.

To keep beaver from plugging outlet tubes, the pond owner should string electrified fence wire around the tube and connect it to a fencer and battery. Wood or fiberglass posts should be used or the system will not work. After beaver have been shocked a few times, the power can be turned off until problems recur. Outlet tubes are easier to keep free of debris if they are covered with a heavy trash rack of welded metal which is periodically cleaned. “Chicken wire” should not be used, as it cannot be cleaned. To prevent cutting of ornamental trees, bases should be wrapped with 1/4-inch wirecloth or similar fence material. No effective repellent is commercially available.

Population Control

Sustained population control is the best damage prevention method available for both animals. Small, stable populations of muskrats and beaver will do little damage. Pond owners should not wait until furbearers become overabundant before initiating control, because by then the damage has been done.

For most pond owners, the most feasible method of population control is to have a local trapper work the pond every year. Everyone, including the surviving animals themselves, benefit from this arrangement. The pond owner keeps the problems to a minimum; the trapper earns money for pelts, and the animals are kept within the capacity of the pond to support them. If the pond owner wishes to try trapping beaver and muskrats, he should contact the Kansas State University Extension Service or the nearest Department of Wildlife, Parks & Tourism office for detailed information on proper equipment and methods. These agencies can also provide names of trappers who are available to help with problems. If damage is severe, muskrats and beaver can be shot or trapped out of season provided a permit is obtained from the Department of Wildlife, Parks & Tourism. Pelts obtained out of season must be turned in to the area Natural Resource Officer. The pond owner may pay a trapper market value for fur that is turned in on a permit as incentive for him to work on problems.

Both muskrats and beaver can be live-trapped although equipment costs may be prohibitive. Beaver can be taken in suitcase-style Bailey or Hancock traps, and muskrats can be taken in wire box traps (Havahart type) that are set on a float made from two- by eight-inch boards. Poisons are not recommended for beaver or muskrats due to undesirable effects on non-target species (particularly fish). A permit is required for use of poisons, and these are seldom issued by the Department of Wildlife, Parks & Tourism.