Muskrats are primarily vegetarians, feeding mostly on the roots and stems of aquatic plants and, if they occur near water, legumes, grasses, grains, garden crops and apples. They occasionally eat animal food, particularly crayfish and fresh-water mussels. Muskrats live in houses constructed of vegetation or in burrows dug into banks. Muskrats breed from early spring until fall, giving birth to several litters of from four to seven young. The young are born naked and helpless in protected nest chambers in houses or bank burrows.
Young muskrats grow rapidly and are independent at an early age.
Although muskrat feeding habits may damage agricultural or ornamental crops growing near water, the principal concern is potential damage to earthen water-retaining structures. Extensive tunneling into earthen dams may cause water leaks or the loss of stored water. Burrowing damage occurs most often in older ponds where the dike is thinner from erosion or is poorly designed. Trees growing on the dike sometimes create problems attributed to muskrats. Tree roots die, and water follows the roots until the dike gives way.