Photo Muskrat 001

Common Muskrat

Ondatra zibethica
Chuck Fergus

Why the name muskrat? "Musk" refers to a strong smelling substance released from this animal’s perineal glands (between the thighs), while “rat” describes its rat-like appearance. The muskrat is a rodent — related to mice, voles, beavers and rats. The nation’s most abundant furbearer, the muskrat lives on or near the still or slow-moving water of ponds, marshes, streams and rivers and, to a lesser extent, faster mountain streams. The species is found over most of North America north of the Rio Grande River, including the coastal tidal marshes. It’s common in Pennsylvania, but nearly abundant as it used to be. Adult muskrats are 22 to 25 inches in length, including the tail. They weigh 2 to 3 pounds, have a stout body, short legs, and an 8- to 12-inch tail that is flattened vertically, scaly and practically hairless. Ears and eyes are small but well-developed. In appearance, muskrats resemble small beavers with long, ratlike tails. The tail functions as a prop when the animal stands on its hind feet, and as a rudder and propulsion- aid when it swims. The muskrat’s large, broad, partially webbed hind feet power it through water. Its forefeet are small and agile, with well-developed claws for burrowing. To insulate against cold water, a muskrat’s underfur is dense, silky and soft, overlain with long, dark brown guard hairs shading to gray-brown on the throat and belly. Overall pelt color can be chestnut brown to almost black, or any color in between.

Muskrats build houses (also called lodges) of vegetation, or they burrow into stream banks, earthen dikes and dams, often causing considerable damage. Both lodges and burrows have underwater entrances and above-water living quarters. Lodges are built of cattail stalks or other vegetation, chinked with mud and weeds above the waterline. They may be 8 to 10 feet across and 2 to 3 feet above water, with a single living chamber plus offshoots, or several chambers. Muskrats do not dam streams.

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Pennsylvania Game Commission
Bureau of Wildlife Management
Attn: Mammal Atlas Coordinator
2001 Elmerton Avenue
Harrisburg, PA 17110
MammalAtlas@pa.gov
Pennsylvania Game Commission
Bureau of Wildlife Management
717-787-5529