In marshes, muskrats eat the roots and stems of cattail, bulrush, arrowhead, duckweed, and water-lily. Clover, corn, and grasses are common foods in agricultural areas. Feeding piles or platforms of shredded vegetation often accumulate where muskrats make a habit of stopping to eat their meals. The breeding season starts in late winter and ends in September. Pregnancy averages 28 days.
Females usually have two litters, sometimes three, per year.
A typical litter has 4-7 young. The young are blind, nearly helpless, and practically naked at birth. By one week of age they're covered with coarse gray-brown fur. Their eyes open between 14 and 16 days of age. About this time the young can swim, dive, and climb on low, floating objects.