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Muskrat

Ondatra zibethicus

Muskrats have thick, glossy fur that varies in color from blackish to silvery-brown. (U.S. Fish & Wildlife Service)
Muskrats have thick, glossy fur that varies in color from blackish to silvery-brown. (U.S. Fish & Wildlife Service)

The muskrat is a semi-aquatic mammal with brownish fur and a long, rudder-like tail. It is found in marshes and other shallow-water areas throughout the Chesapeake Bay watershed.

Appearance:

  • Thick, glossy fur that varies in color from blackish to silvery-brown
  • Paler throat and belly
  • Scaly, hairless, rudder-like tail that is flattened on the sides and can grow to 10 inches long
  • Small ears that are nearly hidden within its fur
  • Partially webbed hind feet
  • Grows to a total length of 16-24 inches and can weigh up to 4 pounds

Habitat:

  • Found mostly in marshes, but also lives in other types of wetlands such as swamps and in ponds, lakes, streams and rivers
  • Prefers shallow areas with 4-6 feet of water
  • Builds a dome-shaped lodge of mud and marsh plants on top of tree stumps in shallow water. Lodges can be up to 3 feet tall and have one or more underwater entrances.
  • Occasionally burrows into stream banks to create a den
  • Mostly nocturnal, but can be seen swimming or sunning itself on a log during the day

Range:

  • Found throughout the Chesapeake Bay watershed

Feeding:

  • Feeds mostly on the roots and rhizomes of marsh plants, especially cattails and rushes
  • Will also eat fish, frogs, insects and shellfish
  • Consumes about one-third of its weight every day
  • Builds separate feeding lodges or platforms so it can get out of the water and eat

Predators:

  • Has many predators, including minks, raccoons, owls, hawks, red foxes and bald eagles
  • Humans hunt muskrats for meat, fur and sport
  • Hides from predators by diving underwater or into its lodge

Reproduction and Life Cycle:

  • Breeds frequently throughout most of the year
  • Nests in chambers inside its lodge
  • Females have 1-3 litters of 5-6 young (called kits) each year
  • Gestationperiod lasts less than one month
  • Young are born blind
  • Within 10 days young can swim and within 21 days they can eat plants
  • After one month, the female ejects her now-independent young from the lodge
  • Can live 3-4 years in the wild

Other Facts:

  • The most common semi-aquatic mammal found in the Bay watershed’s marshes
  • Named for the strong musky odor adults emit to communicate with one another
  • Ondatrais the Iroquois name for the muskrat and zibethicus means “musky-odored” in Latin
  • Poor vision, hearing and smell
  • Can be confused with beavers and nutria. Muskrats can be distinguished by their smaller size and their rudder-like tails that are flattened on the sides.
  • Has fur mouth flaps behind its teeth to prevent water from getting in its mouth while chewing underwater.
  • Has an extraordinary lung capacity. Muskrats have been observed swimming underwater for up to 17 minutes, surfacing for three seconds, and then going back underwater for another 10 minutes.
  • Snakes, turtles, Canadageese and many other animals use the tops of muskrat lodges as habitat

Sources and Additional Information:

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