On a cloudy morning beside a grassy canal on the Kootenai Wildlife Refuge parallel to the Kootenai River I observed a muskrat busily swimming and inspecting the vegetation. In spite of the fact he noticed me I managed to get a few photos before he silently disappeared under the water. Although primarily nocturnal, this squeaky-voiced rodent tends to be a sociable animal and sometimes active by day.
Muskrats get their common name from their resemblance to stocky rats and from the musky odor produced by their scent glands. They are semi-aquatic and prefer locations with four to six feet of water. Muskrats are found in ponds, lakes, and swamps, but their favorite locations are marshes, where the water level stays constant. Marshes provide the best vegetation for eating and constructing nests and burrows. Muskrats find shelter in bank burrows and nests that they build. Bank burrows are tunnels excavated in a bank. Nests are made by piling vegetation on top of a solid base, for example a tree stump, generally in 15 to 40 inches of water.
They have large, robust bodies, with a total body length of 12-24 inches. The tail is long, skinny, scaly and with flat sides and is generally 8-11 inches in length. Muskrats have dense fur that traps air underneath for insulation and buoyancy. Their heads are very large and their ears are almost invisible underneath the fur. Muskrats have short legs and big feet; their rear feet are webbed for swimming. Adult muskrats have glossy upper parts that are dark brown, darker in winter and paler in the summer.
Muskrats live in large family groups with definite territories. If conditions are crowded, females will kick their offspring out of the group. Muskrats continue to live in large groups even when they fight amongst themselves. Muskrats are active at all times of the day but most active from mid-afternoon until just after dusk, and at night. They paddle with their large, webbed rear feet and use their long, flat, and scaly tail to change their direction. Muskrats move slowly on land. They are affected by quick changes in temperature, and dry, hot weather is especially bad for them. Their homes and burrows protect them from the elements.
Muskrats communicate by a secretion from their glands called musk. This scent also serves to warn intruders. They are capable of vocalizing by squeaks and squeals. Muskrats have poorly developed senses of sight, hearing, and smell.
These musky rodents are mainly vegetarians but will eat animals as well. Muskrats consume about one-third of their weight every day. Their digestive system is designed for green vegetation. In the summer they eat the roots of aquatic plants. In the winter, they swim under the surface ice to get to the plants. Muskrats also eat agricultural crops.
Raccoons and river otters are the main enemies, although they are also preyed upon by many other animals. Other predators of the muskrat are coyotes, owls, minks, foxes, wolves, lynx, bobcats, bears, and eagles.
Muskrats are excellent swimmers and can evade many predators by escaping into water or into their burrows and nests. They can remain underwater for up to 15 minutes.
Although muskrats have been known to live to 10 years in captivity, they are thought to live about 3 or 4 years in the wild.
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Correction: Last week’s column had the incorrect photos for the article. The birds in the photos were Clark’s Nutcrackers.