Chesapeake Bay Program - Muskrat

<body> <p><i>Ondatra zibethicus</i>, the common muskrat, is a large, semi-aquatic rodent that inhabits wet environments throughout the Chesapeake Bay watershed, including swamps, lakes and along the shores of rivers and ponds. Its ideal habitat is fresh or saltwater marshes, where the water level remains fairly stable, preferably at a depth of four to six feet. The muskrat's substantial, glossy pelt (once prized by the fur industry for its density and waterproof properties), rudder-like, scaly tail and partially webbed hind feet make it a particularly strong swimmer and diver. Although muskrats are generally herbivorous (consuming both terrestrial and aquatic vegetation such as cattails, water lilies, sedges and rushes), they also will feed on fish, crayfish, frogs, freshwater clams and occasionally carrion. </p> <p>Ondatra is the Iroquois name for this animal, and zibethicus means 'musky-odored' in Latin, referring to the scent that breeding males emit. Mature muskrats achieve a length of between 16 and 24 inches and weigh about four pounds. They have dark brown fur along their backs and lighter-brown fur on their sides, with finer, pale-to-white fur at the throat. Their ears and eyes are small, and their webbed hind feet are larger than their forefeet. Muskrats are able to close their mouths behind protruding incisors, and can chew underwater. They breed frequently, having one to five litters per year, yielding an average of five to six young (sometimes as many as 11). In their northern range, muskrats breed between late winter and early September and generally have larger litters, but in warmer zones they may breed year-round.</p> <table border="0" align="right" cellpadding="2" cellspacing="2" width="184"> <tr> <td width="176"><img src="../images/COM_muskrat1.jpg" alt="Photo courtesy of Marine Biological Laboratory" width="233" height="152" border="0" align="left" usemap="#Map"></td> </tr> <tr valign="top"> <td><em><font size="-1">Photo courtesy of <a href="http://www.nps.gov/" target="_top">National Park Service</a> </font></em></td> </tr> </table><p>Unlike its larger relative, the American beaver, which has a paddle-shaped tail, the common muskrat's tail is vertically splayed, allowing it to use it as a rudder to swim forward or backward with ease. The muskrat's lung capacity also is extraordinary: individuals have been observed swimming underwater for up to 17 minutes, surfacing for three seconds, then resubmerging for another 10 minutes without a breath.</p> <p>Muskrats build dome-shaped lodges similar to but smaller than beavers' lodges (about 4 3.5 feet in diameter), in areas that contain an abundance of the same vegetation that constitutes their diet, such as bulrushes, cattails and burreed. They will sometimes substitute bark, mud or small sticks. Lodges contain nesting chambers, which they keep clean and free of droppings, and one or more underwater entrances. Occasionally muskrats create dens containing several chambers by tunneling into the banks of rivers or wetlands, and construct several entrances below the water line. They also build feeding platforms that provide some shelter while they eat. Muskrats usually live alone, although occasionally will share a lodge, except while breeding.</p> <table border="0" align="left" cellpadding="2" cellspacing="2" width="184"> <tr> <td width="176"><img src="../images/COM_muskrat2.jpg" alt="Photo courtesy of Marine Biological Laboratory" width="233" height="155" border="0" align="left" usemap="#Map"></td> </tr> <tr valign="top"> <td><em><font size="-1">Photo courtesy of <a href="http://www.nps.gov/" target="_top">National Park Service</a> </font></em></td> </tr> </table><p>Female muskrats give birth to several litters of up to 11 young a year. Gestation takes about 29 to 30 days. At birth muskrats weigh about 22 grams, have short dark fur and closed eyes. Within about 10 days they can swim and at three weeks may eat green vegetation. By the time they're a month old, the young are independent and are ejected from the nest by the mother. </p> <p>Muskrats are nocturnal and most active at dusk, dawn or after nightfall, but they can be seen during the day in all seasons, sunning themselves on logs or swimming. Their range extends throughout North America, north of Mexico and south of arctic regions. Muskrats are abundant in the eastern U.S., California, the southwest, Texas and Florida. In New York State their grazing activities have been studied for their effects on plant biomass and wetland ecology; scientists hypothesize that muskrats increase the diversity of flora by decreasing, in noticeable quantities, the biomass of <i>Typha angustifolia</i>, the narrowleaf cattail.</p> <TABLE border="1" cellpadding="0" cellspacing="0" bgcolor="#C6C68C" width="100%"> <TR bgcolor="#C6C68C" valign="top"> <TD><STRONG> Other Sites of Interest: </STRONG> <UL> <LI><A href="http://animaldiversity.ummz.umich.edu/site/accounts/information/Ondatra_zibethicus.html" target="_top">University of Michigan Museum of Zoology</A> - Animal diversity web</LI> <LI><A href="http://www.fcps.k12.va.us/StratfordLandingES/Ecology/mpages/muskrat.htm" target="_top">Stratford Landing Elementary School</A> - Looks at the common muskrat</LI> <LI><a href="http://www.pwrc.usgs.gov/resshow/rattner/bioeco/preamble.htm" target="_top">Patuxent Wildlife Research Center</a> - Biological and Ecotoxicological characteristics of the muskrat</LI> <LI><A href="http://www.enature.com/fieldguide/showSpeciesGS.asp?sort=1&curGroupID=99&display=1&area=99&searchText=Ondatra+zibethicus&curPageNum=1&recnum=MA0086" target="_top">Enature</A> - Field guide looks at the common muskrat</LI> </UL> </TD> </TR> </TABLE> <hr noshade> <div align="center"> <center> </center> </div> <p align="center"><font face="Times New Roman" size="2">To bookmark this page, please use this URL: <a href="../critmon.htm" target="_top">http://www.chesapeakebay.net/critmon.htm</a> </font></p> <p align="center"><font size="2"> For more information, contact the Chesapeake Bay Program Office:<br> 410 Severn Avenue, Suite 109, Annapolis, MD 21403 / Tel: (800) YOUR-BAY / Fax: (410) 267-5777</font><font size="2">.</font></p> <p align="center"><font size="2"><a href="../termsofuse.htm" target="_top">Terms of Use</a> | <a href="../privacypolicy.htm" target="_top">Privacy Policy</a> | <a href="../comments.htm" target="_top">Contact Us<br> </a></font><font size="2"><a href="http://www.chesapeakebay.net/directions.htm" target="_top"> Directions to the Bay Program Office</a></font><br> <a href="http://www.chesapeakebay.net/cims" target="_top"><img src="../images/cims1.gif" height="19" width="51" border="0" align="left" vspace="10" alt="Chesapeake Information Management System (CIMS) "></a><a href="javascript:print()"><img src="../images/print.gif" width="31" height="38" border="0" alt="Print Current Page" align="right"></a><br> <font size="2">Last modified: 11/01/2004 </font> </p></body>