Muskrats can sometimes weigh more than 4 pounds (2kg). They have thick waterproof coats, webbed hind feet, and a flat tail which they use as a rudder. Normally muskrats burrow into riverbanks. However, if the ground is flat they will often make a home by piling plants into a heap up to 3 feet (1m) high. Muskrats eat plants that grow next to the water. Sometimes they will also eat small animals.