Ondatra zibethicus
muskrat

The muskrat is found in swamps, marshes, and wetlands from northern North America to the Gulf coast and the Mexican border. Early in the 20th century, muskrats were introduced to northern Eurasia (Baker, 1983).

Muskrats are found in wet environments, favoring locations with four to six feet of water. While muskrats are found in ponds, lakes, and swamps, their favorite locations are marshes, where the water level stays constant. Marshes provide the best vegetation for muskrats. They find shelter in bank burrows and their distinctive nests. Bank burrows are tunnels excavated in a bank. The nests of the muskrats are formed by piles of vegetation placed on top of a good base, for example a tree stump, generally in 15 to 40 inches of water (Baker, 1983).

Muskrats have large, robust bodies, with a total body length of twelve and a half inches. The tail is flat and scaly and is nine and a half 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. The whiskers are mediun size. Muskrats have short legs and big feet; the back feet are slightly webbed for swimming. Adult muskrats have glossy upperparts that are dark brown, darker in winter and paler in the summer (Baker, 1983).

Although muskrats have been known to live to 10 years old in captivity, they probably live about 3 years in the wild.

Muskrats are arranged in large family groups and live in definite territories. If the conditions are overcrowded, the females will kick their offspring out of the group. Muskrats continue to live in large grous even when fighting and cannibalism occur in high rates. Muskrats are active at all times of the day but most active from mid-afternoon until just after dusk. Muskrats are good swimmers and can stay underwater for 12 - 17 minutes. Muskrats, however, move relatively slowly on land. Muskrats communicate by musk, which also is used as a warning for intruders. They are capable of vocalizing by squeaks and squeals. Muskrats have poorly developed senses of sight, hearing, and smell. 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 also have a special adaptation called regional heterothermia, which regulates the flow of blood to the feet and tail, allowing these structures to be cooler than the body core (Baker, 1983).

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.

Muskrats 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 (Baker, 1983).

Muskrats are excellent swimmers and can evade many predators by escaping into water or into their burrows and nests. They can remain under water for up to 15 minutes.

Muskrats are very abundant in areas of good habitat, making them important prey animals for predator populations. By grazing on vegetation, muskrats influence the composition of local plant communities.

The fur of a muskrat is important in the fur industry. Also, the meat from a muskrat is suitable for human consumption (Baker, 1983).

Muskrats not only eat the grain on a farm but they have also been known to plug the drain tiles on farms as well. Muskrats also have a habit of building their homes around dikes. These homes make the dikes weak and eventually destroy the structure (Baker, 1983).

Muskrats are widespread and abundant. Populations remain stable even when they are being hunted for fur, affected by disease, or a target for large predator populations because muskrats have the ability to reproduce quickly.