Male has large round chestnut-red head, black beast and under tail, gray body. Bill is blue with dark tip.
Females are uniformly brown.
Breeds primarily in the Prairie Provinces and intermountain valleys on freshwater marshes and potholes as far south as Nevada, Arizona, and Colorado, and as far east as New York. Winters primarily along the Gulf coast of Texas and northeastern Mexico, with lesser concentrations in Florida and the Yucatan peninsula. Secondarily, winters on coastal bays of the Pacific coast, especially in Sonora and Sinaloa. In California, breeds locally on northernmost refuges and in Central Valley. Eats submerged vegetation in sloughs, lakes, and marshes.