Ondatra zibethicus

Order: Rodentia
Family: Cricetidae

Status: Very abundant.  One of the most important fur animals in North America.  Can cause damage to dikes by burrowing.  Very valuable fur animal.  Official Montana furbearer managed and protected by regulated fur harvest seasons.

Identifying Characteristics: Muskrats are large voles adapted to aquatic conditions.  The name muskrat is related to odoriferous secretions from the perineal glands.  The long naked tail flattened laterally distinguishes muskrats from other mammals.  Webbed hind feet.  Fur is dense and rich brown and a coarse guard hair overlay and thick waterproof underlayer.  Color varies from dark brown to black.  Total length: 16 to 26 inches.  Weight: 2 to 4 pounds.

Habitat: The most widespread of North American microtine (a subfamily of mice) rodents.  Marshes, edges of ponds, lakes, streams, cattails, and rushes are typical habitats.  An essential habitat ingredient is water of sufficient depth or velocity to prevent freezing.  The presence of herbaceous vegetation, both aquatic and terrestrial, is another essential ingredient.  In general, has very flexible habitat requirements and often coexists in habitats used by beavers.

Food Habits: Primarily herbivorous and will eat virtually any vegetable matter.  Utilizes shoots, roots, bulbs, and leaves of aquatic plants.  Cattails and bulrush are preferred foods.  Will also consume cultivated crops.  On occasion will eat animal matter.  Food is stored in the burrow or den and during winter may even eat part of its own lodge.

 Life History: May be thought of as an overgrown subaquatic vole.  Mostly active at night but daytime activity is not unusual.  Often builds conspicuous dome-shaped houses.  Breeds during spring and summer.  5 or 6 young are born after a 22 to 30 gestation.  May have two or three litters per year.

Similar Species: Beaver - has large dorsally flattened scale over tail.

STATEWIDE SEASON DATES: November 1 - April 15 of the following year, except state Wildlife Management Areas and specific closures (See SPECIAL REGULATIONS). Limit: None. Traps may be set in muskrat houses provided the part removed is replaced after insertion of the trap and after removal of the trap. It is unlawful for any person to willfully destroy, leave open or partially destroy a muskrat house (MCA 87-3-503).