|[Note Guidelines] Photographer's Note|
|This young Common Muskrat was out trying to find a new home. It was captured searching a runoff stream, but the water will soon be gone so I hope it finds a new home soon. This image was shot in the Cypress Hills.|
By Gustave J. Yaki
The muskrat, a member of the Family Cricetidae, is our largest vole. It is particularly adapted to an amphibuous life. For many humans, it is of most interest as a fur-bearer, with from one to four million pelts taken in Canada each year. Its flesh is also readily eaten.
The Common Muskrat occupies most of the USA and Canada although those on Newfoundland may be a separate species. It is absent from Florida and the arid portions of the southwestern states -- and in Canada, in southwestern B.C. and most of the northern tundra. It was introduced to Anticosti Island, Vancouver Island and the Queen Charlottes.
It was also introduced to Tierra del Fuego at the southern tip of South America as a fur-bearer. Of course, since it did not evolve in that environment, it is now wreaking havoc with the ecosystem there.
In appearance, the muskrat looks like a giant vole. It possesses long, lustrous, rich-brown guard hairs and a dense, soft, lead-grey, waterproof underfur. The underside is silvery. Its short ears are hidden in the fur. The long, bare, scaly, black tail is vertically compressed, with hairy fringes on the top and bottom. The hind feet are webbed. Its fleshy, furred lips close behind the orange incisor teeth enabling it to gnaw below water without letting any into its mouth.
Average male measurements are: total length, 572 mm (23 in); tail, 256 mm (10 in); weight, 1.13 k (2.5 lb). Females are slightly smaller.
Spending most of its time in water, the muskrat is an excellent swimmer. It can go long distances under water -- one-hundred metres or more --and remains submerged for two to three minutes. When stressed, it has been known to stay under for 17 minutes. The tail, besides serving as a rudder, may assist in propulsion by moving from side to side. When loafing, it sometimes hold the tail above the water surface.
Muskrats live in sloughs, marshes, lakes and streams where there is aquatic vegetation. They live in family units, defending an area at least sixty metres across. In autumn they leave shallow wetlands (which might freeze to the bottom), travelling overland to seek areas that will provide for their winter survival. They avoid wetlands more than four metres deep because it will lack submergent vegetation.
In summer muskrats feed mostly on readily available emergent vegetation -- broad-leaved cattail, bulrush, sedges, sweet flag (Acorus), arrowheads, water lily and pondweeds. They also partake of animal matter, in particular, freshwater mussels. It is also reported that they consume frogs, salamanders, small turtles and slow-moving fish. They apparently do not store food for winter use. In winter, they add the less palatable coontail, water milfoil, bladderwort, water lily tubers and bur-reed to their diet.
Besides humans, muskrats become food for many other species. Mink are probaly their main predator. However, especially when travelling across land in autumn and spring, they become easy prey for Gray Wolves, Coyotes, Red Foxes, Black Bears, Canada Lynx and Bald and Golden Eagles, Northern Goshawks and Great Horned Owls. Aquatic predators such as Northern Pike and Snapping Turtle take some young muskrats.
Typically, their winter home is a mass of vegetation -- cattails and bulrushes plastered with mud, built near deep water. This mass, which may rise to almost a metre above the water surface level, freezes solid in winter, discouraging predation by wolves or other carnivores. The muskats cut out a below-water entrance and make a dry sleeping platforms inside. In building this shelter, they always provide a small opening at the top, allowing the moist, stale air to escape.
Muskrats also use bank dens if there is sufficient nearby firm ground and depth so that they can enter from below water-level. The tunnel leads upward one to ten metres, to warm dry chambers. Muskrats prefer to raise their young in these bank burrows. In summer, if the wetland becomes shallow because of evaporation or drought, muskrats may dig a series of water-filled canals radiating from their home.
In Canada the breeding season is March to September. They appear to be monogamous. The gestation period is 22 to 30 days. The females take possession of the closest bank dens, forcing the excess males and females to vacate, to give birth to a litter of one to eleven young. Normally two litters are produced in Canada. (In Louisiana, it ranges from three to six litters a year). The young are weaned between day 21 and 28, and are independent by one month of age.
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