 |
Camping & Wilderness |  |
Parks & Conservation |
 |
Wildlife & Biodiversity |
 |
Monitoring the Environment |
 |
Fishing |  |
Hunting & Trapping |
 |
Education & Youth |
 |
Publications, Maps & Data |
Muskrat
Page Index:
The Species: Ondatra Zibethicus
High in the water, a muskrat swims, sun dancing on the water around it. Then, spooked by a shadow, it dives below, to a world of pondweed and milfoil. With a long tail as rudder, and partly webbed hind feet as propellers, the "rat" glides to its bank burrow's safety.
Largest of New World mice, the muskrat dips and dives in shallow waters from the Mackenzie Delta to northern Mexico. Throughout North America, it is praised as a maintainer of wetlands and bearer of dense, lustrous fur. Here in the Yukon, it's an important part of the local economy for the people of Old Crow.
Distribution
Muskrats live in streams, rivers, potholes, and shallow lakes throughout the Yukon south of the British Mountains. With limited habitat in the south, most of our muskrats are found in the north, on the extensive wetlands of Old Crow Flats. There, muskrats outnumber any other species of mammal, with five rats per hectare, an area about the size of a baseball field.
Characteristics
The muskrat is really a giant field mouse that has traded meadows for marshes. Like its vole and lemming cousins, it has a plump body, small ears, and beady, little eyes. However, the muskrat is far larger, with a body and tail that stretch half a metre. Its most distinctive feature, and one that distinguishes the muskrat from all other mammals, is a long, naked tail that is scaly, black, and flattened from side to side.
Weighing about a kilogram, our northwestern rat has a thick, dark brown coat and is up to 40% smaller than other Canadian muskrat races.
Life in Shallow Waters
Mud churns as a muskrat plunges into the frigid water of an underwater entrance to its stream bank burrow. Leaving the warmth of its nest behind, the rat enters the stream and swims beneath metre-thick ice, stopping on the bottom here and there to search for dormant plants. It uses nimble forefeet to dig up roots and underground stems of pondweed, water milfoil, and burr-reed. Then, with food in its mouth, and forefeet tucked beneath its chin, the rat paddles on to an open hole in the ice. There it climbs up into a dome-shaped resting and feeding station called a pushup.
Muskrats build pushups by first chewing plunge holes in thin autumn ice at cracks and bubbles and places where marsh gases escape. Then they pile mud and plants into domes above the holes. When frozen solid and covered with snow, these domes close in air and close out winter's worst weather.
Using a line of pushups stretching away from its burrow, a muskrat can gather food farther than it could otherwise reach. As well as providing insulation from cold air temperatures, pushups also provide relief from icy waters that quickly rob heat from the muskrat's naked tail and feet. And if the underwater entrance to the muskrat's bank burrow should freeze over, it can use pushups as temporary homes.
Come spring, the fresh winds and warm sun of May melt old ice and free Yukon muskrats from more than half a year under ice. Only 10% to 40% of those alive in autumn survive winter, and few live past their second year.
Breeding starts soon after break-up, in late May or early June. Those muskrats that once shared winter dens and huddled to conserve heat now bare their teeth in disputes over burrows and borders. Aggressive and possessive, muskrats fight viciously to obtain and defend their territories -- patches of shallow wetland where they can mate and raise young.
Winners of breeding wars warn other muskrats away by secreting a musky substance onto shoreline scent posts made of cut stems and mud. Losers search elsewhere for territories. These "runners" may travel up to twelve kilometres. Many are killed by other muskrats, mink, otters, foxes, coyotes, marsh hawks, and great horned owls.
During the long days of mid-summer, muskrat litters are born in nesting chambers dug deep into stream banks and lake shores. A pair of Yukon muskrats produces only one litter each year, with an average of eight kits per litter. By comparison, two or three litters are the norm in Ontario, and up to five or six in Louisiana.
Blind and nearly naked, newborn muskrats weigh about the same as a mouse. Within a week, their large, ever-growing incisors erupt, and soon after, the kits are covered in gray-brown fur. At two weeks they take to the water, buoyed up by a layer of air trapped in their dense fur.
Spending most of their time afloat, muskrats feed on pondweeds, bur reeds and water milfoil, as well as horsetails growing along the shore. These foods are less nourishing than the cattails and bulrushes of southern marshes. This fact, along with our short growing season, may explain why Yukon muskrats have fewer young, and why Yukon kits gain weight only half as quickly as Ontario kits.
At four weeks of age, kits are weaned. Though independent, many remain in their parents' territories until autumn, when drought or freeze-out can force muskrats to abandon summer territories for deeper water. In good habitat, kits may remain near their parents until the breeding battles of spring force them to leave in search of a space where they too can reproduce.
Muskrats and People
In the old days, Yukon First Nations people caught muskrats by setting spring-pole snares in the grass along rat trails. Now, they and other trappers set steel traps underwater in pushups or lure muskrats into shooting range by cupping hands over mouths and imitating the whining noises of young rats or the calls of seductive females. Muskrats are especially important to the Vuntut Gwich'in of Old Crow and have provided up to three-quarters of their annual fur harvest income.
Spring "ratting" is also a social event and part of the traditional lifestyle of many Yukon First Nations. Not only does ratting provide furs and meat for people and dogs, it's also an opportunity for whole families to get out on the land, celebrate spring's arrival, and hunt other game, such as waterfowl and caribou.
Viewing Opportunities
The key to seeing muskrats is finding shallow wetlands with plenty of aquatic plants. Muskrats often share beaver houses and ponds, so look for both species in beaver country.
River travellers have excellent chances of spotting muskrats in slow, meandering, marshy stretches. Lake and highway travellers, as well as hikers, may see muskrats in any shallow, productive waters. Keep an eye out for brown bodies afloat or hunched amid sedges on shore.
Note that muskrats swim with their heads and backs out of the water, whereas beavers show only their heads and trail a characteristic "V" wake. Note also that muskrats are most active in the twilight hours, but can often be spotted during the day as well.
After freeze-up, look for dome-shaped pushups in the ice. They're most visible before snowfall or after the snow has melted from the surface of thick ice in spring.