Muskrat (Ondatra zibethicus)

Minnesota’s most abundant and prolific furbearer is found throughout the state. Look for these mammals near water year-round—but you may not see as many as you used to. North American muskrat populations are in decline.

Appearance. Despite their common name, muskrats are semiaquatic voles, more closely related to lemmings than rats. They are uniquely equipped to live in lakes, streams, and rivers where calm water combines with emergent vegetation—plants that grow up and out of the water. Muskrats have a long, vertically flattened tail with a thick underlayer of waterproof fur topped by coarse, silvery guard hairs. With their large hind feet, they propel themselves through the water—both forward and backward—aided by stiff guard hairs fringing their toes. Their front feet are tiny and hand-like, used for digging burrows, holding food, and building lodges. The first part of their name refers to a strong musk emitted from glands of both sexes.

Populations. The muskrat was once regarded for its perseverance, but scientists are beginning to question its resilience. In one study, biologists documented declines of mean muskrat house counts above 90 percent in two large Great Lakes coastal wetlands. An analysis of harvest data from the United States and Canada also suggests a widespread reduction in muskrat numbers.

Habitat. Muskrats live near water in most of the United States, extreme northern Mexico, all of Canada, and most of Alaska. They prefer wind-protected areas with emergent vegetation and stable water levels, but they often live in less-than-ideal conditions. A hybrid cattail (Typha x glauca) began invading North American wetlands around the same time biologists and conservationists began noticing declines in muskrat numbers. The hybrid cattail changes the structure of the wetland, reducing open water and degrading habitat, but its impact on muskrat populations is not fully understood. Scientists are continuing to study how the hybrid cattail affects wetland wildlife.

Shelter. Muskrats live in lodges and burrows under the banks of streams and wetlands. Lodges are masses of vegetation, piled in a shallow area. Muskrats hollow out the lodge from below; it may house multiple chambers. Burrow entrances are usually underwater.

Behavior. Muskrats are mostly vegetarian but will eat fish and other animals. During the winter, they rely on under-ice food like grasses, roots, and small branches that are frozen below the waterline. From late summer to winter they tolerate close contact, sometimes huddling for warmth. During the breeding season, males and females become aggressive toward each other, fighting for space and mates.