Muskrats

OVERVIEW

Muskrats are large rodents that live near freshwater wetlands and feast on aquatic plants throughout North America. Classified as fur-bearing animals, muskrats are a valuable source of fur and may only be trapped during certain times of the year by licensed hunters. They are excellent swimmers able to hold their breath for up to 15 minutes and move at speeds of 3 miles per hour.

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Biology & Behavior

The range of the muskrat extends across most of North America. The muskrat spends its life in aquatic habitats and is well adapted for swimming. Its large hind feet are partially webbed and its laterally flattened tail is almost as long as its body. The muskrat has a stocky appearance, with small eyes and very short rounded ears. Its front feet are smaller than its hind feet and adapted primarily for digging and feeding. ​The overall length of adult muskrats is usually from 18 to 24 inches. Large males however will sometimes be more than 30 inches long, 10 to 12 inches of which is the laterally flattened tail. The average weight of adult muskrats is 1.5 to more than 4 pounds. The color of the belly fur is generally light grey to silver to tan, and the remaining fur varies from dark tan to reddish brown, dark brown, and black. ​Muskrats can live where water and food are available year round. In shallow water areas with plentiful vegetation, they use plant materials to build houses, generally conical in shape. Elsewhere they prefer bank dens and in many habitats they build both bank dens and houses of vegetation. ​Muskrats are mainly herbivores. They will eat almost any aquatic vegetation as well as some field crops grown adjacent to suitable habitat. Although primarily herbivores, muskrats will also feed on crayfish, mussels, turtles, frogs, and fish. ​Muskrats generally have a small home range and are rather territorial. During breeding season some dispersal is common. Dispersal of males, along with young that are just reaching sexual maturity begins in the spring. The availability and accessibility of food impact population levels. ​Both male and female muskrats become more aggressive during the breeding season in defending their territory. Litters may contain as many as 15 young. But generally average between 4 and 8. Young may be produced any month of the year.

Diseases

Damage

Muskrats are host to large numbers of endoparasites and exctoparasites. They serve as carriers of a number of diseases, including tularemia, hemorrhagic diseases, leptospirosis, ring worm disease, and pseudotuberculosis. Most common exctoparasites are mites and ticks. Endoparasistes are predominately nematodes, cestodes, and trematodes. ​Burrowing activity is a source of the greatest damage caused by muskrats. They damage pond dams, floating styrofoam marinas, docks and boat houses, and lakeshores. In water fowl marshes, muskrat population eruptions can result in the virtual elimination of aquatic vegetation in large areas. In aquaculture reservoirs, muskrats cause damage by burrowing into levees or pond banks. ​

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