Muskrats derive their name from the "musky" odor they secrete from glands in the perineal region, and which they use to scent-mark their territory during mating season. While you will probably first notice them trundling about on the banks of the Willowbrook, muskrats are aquatic, with slightly-webbed hindfeet and a laterally flattened tail which they use like a rudder in the water to steer. Their laterally flattened tail is unique to muskrats; no other rodents have it, and it is the key to identifying them, along with their dark brown, waterproof fur and silvery bellies. Muskrats are most at home in the water; they can swim either backward or forward with ease. While muskrats normally surface to breathe every few minutes, they can remain submerged for as long as 17 minutes at a time. Muskrats are especially crepuscular (active at dusk and dawn), but they may be active at any time in the day.

To make their homes, muskrats burrow into a suitable bank below the waterline, with a tunnel which extends to a den up to 10 m (11 yards) away from the burrow opening. They keep their houses scrupulously clean and never deposit fecal matter in them. In "wilder" environs, muskrats will build a house out of vegetation -- especially cattails -- plastered with mud along a marshy area, stream, lake, or water banks. Swans have been known to build their nests on the tops of these mounds.

Muskrats feed on the roots of water plants like sedges and cattails, but they will also eat crabs, fish, frogs, crayfish, clams, and similar foods when available. They often create feeding platforms of cut vegetation in water or on top of standing ice, but they can also chew underwater and often graze on roots below the surface.

Mating pairs of muskrats can produce one to three litters per year of six to eight young per litter and youngsters remain with parents until they are mature (up to a year). In northern climes like New York City, they often produce fewer litters per year, breeding from April through early September. The period of gestation is 25 to 30 days. This high rate of fertility and human eradication of their chief predators (which are often mink) regularly leads to over-population; in this situation, hungry muskrats can become nuisances, raiding gardens and farms when food becomes scarce. But muskrats also benefit human communities by keeping down algae growth in marsh areas and regulating the succession of marshlands. During the fur trade especially but continuing today, muskrats have been much sought after for their fur, which is soft, durable, and waterproof. Many communities have sought muskrats for their meat, which is known as "marsh rabbit" and is highly nutritious.

For more information about muskrats:

Ken VanEseltine’s "Everything Muskrat Page" (http://www.net_link.net/~vaneselk/muskrat/), has EVERYTHING, including muskrat biology, muskrat recipes, muskrat film clips, and muskrat humor.

Killdeer Countryside Virtual Wetlands Preserve, “Muskrats: Introduction, Habitat, Human Interactions, Niche in Food Web, Adaptations, Life Cycle," http://209.174.10.129/wetlands/Muskrats/Muskrats.html.

Toni Lynn Newell and Tricia Jones, “Ondatra zibethicus: Muskrat," (including views of muskrat skulls), University of Michigan Museum of Zoology Animal Diversity Web, May 2000, http://animaldiversity.ummz.umich.edu/accounts/ondatra/o._zibethicus$narrative.html.

Mark E. Kalin, “Muskrat," (1998/12/13), http://biology.wsc.mass.edu/biology/courses/hoag/mammal/98fall/spacc/ozibethicus.html.

Ruth Nissen, “Muskrat Life," Environmental Protection Agency’s Mississippi River Tidbits on Mammals, July 16, 1997, http://www.epa.gov/reg5ogis/t_mams.htm.

“Manabozho and the Muskrat," an Ojibwe story, in Canku Ota -- A Newsletter Celebrating Native America (July 15, 2000 _ Issue 14), http://www.turtletrack.org/Issues/Co07152000/CO_07152000_Muskrats.htm.

Tom Isern (Professor of History, North Dakota State University), “Plains Folk: Muskrats and Mink," NEWS for North Dakotans, 30 April 1998, http://www.ext.nodak.edu/extnews/newsrelease/1998/043098/25plains.htm.

The U.S. Geological Survey’s “Biological and Ecotoxicological Characteristics of Terrestrial Vertebrate Species Residing in Estuaries" (http://www.pwrc.usgs.gov/resshow/rattner/bioeco/muskrat.htm).

Kevin L. Campbell and Robert A. MacArthur, “Nutrition and the energetic tactics of muskrats (Ondatra zibethicus): morphological and metabolic adjustments to seasonal shifts in diet quality," in Canadian Journal of Zoology/Revue canadienne de zoologie (Volume 76, Number 1, January 1998): 163_174, http://www.nrc.ca/cisti/journals/cjz/z97_182.html.

Campbell, K.L. and R.A. MacArthur. 1996. Seasonal changes in gut mass, forage digestibility and nutrient selection of wild muskrats (Ondatra zibethicus). Physiological Zoology. 69(5):1215_1231. http://home.cc.umanitoba.ca/~rmacarth/pz1996.html.

Farm Security Administration photographer Marion Post Wolcott took a series of photographs of a group of muskrat hunters on Delacroix Island, in Louisiana, available via the American Memory Project at the Library of Congress. At least one image records the habits of muskrats: House built by muskrats.

Dave Barry (humor columnist for the Miami Herald), “You can eat a poinsettia, but beware of muskrats," 9 February 2000, http://www.phillynews.com/daily_news/2000/Feb/09/opinion/DAVE09.htm.