The common muskrat (Ondatra zibethicus) is a relatively large, semi-aquatic rodent found in wetlands, streams and other aquatic areas across West Virginia. Its hair is usually rich brown but may vary from tan to red to almost black. Its back is usually darker than its sides due to the black-tipped guard hairs. Muskrats average 1.5 to 2 feet in length and weigh between 2 and 3 pounds, with some rare specimens weighing close to 4 pounds. Muskrats have larger back feet that are webbed for swimming and smaller, unwebbed front feet used for digging and feeding. The muskrat’s tail is sparsely haired and laterally compressed with a ridge at top and bottom. Named for the musky odor produced in its scent glands, the muskrat uses this musk to mark territories during the breeding season.
Muskrat Life Cycle
Muskrats usually breed at one year of age and can have multiple litters per year. Litter size varies from four to seven kits per litter with gestation lasting around 30 days. Population sizes fluctuate, varying from location to location, depending on competition, food resources and water levels. Muskrat populations can grow rapidly; however, trapping, predation, competition and other mortality factors limit population eruptions. Other than humans, muskrat predators include mink, great-horned owls and marsh hawks. Minks are especially adept at feeding on muskrats.
Muskrat Feeding Habits
These herbivores feed on the roots, stalks and leaves of numerous aquatic plants. They may also travel into agricultural fields feeding on crops. Muskrats can close their lips behind their teeth to cut vegetation under water. They may also feed on fish and aquatic mussels; however, these usually make up only a small portion of their diet.
Muskrats typically build dens of either underground burrows or vegetation domes in farm ponds, streams, ditches and lakes with stable water levels and abundant aquatic vegetation. Both underground burrows and vegetation domes will have underwater entrances.
Damage from muskrats includes chewing on trees, damage to agricultural crops, or washouts of levees and dams. Muskrats will burrow into levees or dams to build tunnels and dens. This burrowing activity can potentially compromise the integrity of these structures by erosion and cave-ins causing washouts. Populations that experience an occasional eruption can cause “eat outs” where they significantly reduce or completely remove vegetation in a wetland due to over foraging.
Muskrats are considered a furbearer species in West Virginia and can be trapped during the annual trapping season (typically between early November and late February.) There is no bag limit during the season. If muskrats are causing damage outside of the regulated trapping season, contact your local West Virginia Division of Natural Resources to determine if a damage permit can be obtained for trapping or shooting.
Harvest data and biological reports suggest a decline in the muskrat population in West Virginia and across the United States. Fur harvest reports have declined from 5,909 muskrats in 2012-2013 season to 1,900 during the 2016-2017 season. While these harvest trends do not show us the entire picture, these trends are similar to those in other states in our region and indicative of population declines. For more information on muskrats, contact West Virginia University Extension Service Wildlife Specialist Sheldon Owen.
Author: Sheldon Owen, WVU Extension Wildlife Specialist
Last Reviewed: October 2018