Pond and Lake Wildlife: Muskrats

Muskrats are a common, semi-aquatic rodent native to the United States. They spend a large amount of their life in aquatic habitats and are well adapted for swimming. Although muskrats are an important part of native ecosystems, their burrowing and foraging activities can damage farm ponds and lake impoundments.

An adult muskrat typically weighs about 2.5 pounds and is 22 to 25 inches long, including its 11-inch black tail. The vertically flattened tail, which is scaly and practically hairless, is used as a prop when the animal is on its hind feet and as an aid to swimming. The large, broad hind feet are partially webbed and well-adapted for swimming.

Muskrats feed mostly on the roots and stems of aquatic plants, but also eat foods such as legumes, grasses, grains, garden crops, and apples if they grow near water. Muskrats can also occasionally eat crayfish and freshwater mussels.

Muskrats build houses called lodges or burrow into stream banks, earthen dikes, and dams usually 6–18 inches below the surface of the pond or lake, often causing considerable damage. The houses and burrows have underwater entrances and above-water living chambers. Muskrats also commonly occupy abandoned beaver lodges or bank dens.

Problems Muskrats Can Cause

The principal cause for concern is the potential damage to ponds and lake impoundments. Damage occurs from muskrat burrowing and tunneling activities that may result in water leaks or the loss of stored water. This may cause leaks, muddy water, and collapse in poorly designed ponds. Erosion due to muskrat burrows and dens can also cause cave-ins and the collapse of some structures.

Dealing with muskrats is much easier if done before the population has become established in an area, so watch for signs of muskrats and adopt control measures as soon as you find evidence of their presence.

How to Keep Muskrats out of Your Pond or Lake

The first step for controlling nuisance muskrats is to find where they are living. Walk near the edge of the water and look for underwater tunnels that lead to their dens. Den entrances are usually located a few inches to three feet below the water level. Signs that a muskrat den is nearby include muddy water, floating vegetation, and pellet-sized droppings on rocks along the shoreline.

Riprapping with coarse stone or gravel may discourage muskrats from digging and burrowing into the pond banks and dams. Apply the material in a layer about six inches thick, extending from one foot above to three feet below water level. This method of damage prevention also protects the pond banks and dams from wave action.

One- or two-inch galvanized wire placed along the water’s edge will discourage muskrats from burrowing. Lay the wire flat against the banks and fasten it down every few feet to keep it in place. The wire should extend from one foot above to at least three feet below the water level. The wire will eventually corrode, so this method is not recommended for ponds where people will be swimming.

Trapping is the most effective method for controlling muskrats that are causing damage. Contact the Pennsylvania Game Commission for information on hunting and trapping licenses that are available for Pennsylvania residents.