Muskrats do not build dams or fell trees as do beavers; their burrows are constructed above water level and are connected to an underwater entrance by a tunnel. They swim by paddling with the hind feet, using the tail as a rudder. Musk secretions are used with droppings and urine to mark out territories.
They feed on vegetation and aquatic animals; their chief enemy is the mink. Mating occurs in spring and summer. The gestation period is about 30 days and the female bears several litters of 2 to 6 young each season.