Muskrat

Size

An adult muskrat is about 40 to 60 cm (16 to 24 inches) long, almost half of that tail, and weighs from 0.7 to 1.8 kg (1.5 to 4 lb). That is about four times the weight of the brown rat (Rattus norvegicus), though an adult muskrat is only slightly longer. Muskrats are much smaller than beavers (Castor canadensis), with whom they often share their habitat.

Food

Muskrats are primarily plant eaters.  The foods are chosen on the basis of what kind of plant species are available, and how much is available, and how well the muskrat likes the taste.  When clams, frogs, crayfish, carrion, and rough fish are locally abundant, they are eaten.  Muskrats will try tasting plants that grow on the water’s edge, although the main part of the muskrat’s diet in Wisconsin is stems and leaves of plants such as bulrushes, cattails, sweet flag, reeds and arrowhead.  In agricultural areas they may eat corn or other crops if the regular foods of this rodent are scarce.  Tubers, as well as underwater roots and pond weeds, are important sources of food in winter when the ice does not allow the muskrat to forage on land.

Habitation

The muskrat can be found in lakes, ponds, sloughs, calm rivers, marshes, streams, and swamps.  Their home can be a hole dug in a bank.  They are also known to build a house of vegetation and mud.  It looks something like a beaver lodge.  The muskrat builds the main lodge in fall by cutting aquatic plants.  They then pile it into a mound on top of a log or stump as a base.  The muskrat then burrows upward from the bottom of the pile of vegetation to a point above the water level in the middle of the pile.  Next is the project of hollowing out a series of small chambers for resting locations and tunnels used as exits and entrances.  During winter several muskrats may live together in one chamber.  The body heat of the group of muskrats keeps the single chamber a whole lot warmer than the temperature of the outside world.  The muskrat’s body heat also keeps the underwater entry clear of ice.