In 1982, harvest restrictions were implemented and the population appears to have stabilized, but is well below its historic numbers. Males in breeding plumage have brown heads, gray bodies and black tails. The female is similar, but more brown in color. The legs are yellow. This is the only puddle duck with white in its speculum.
Food is basically aquatic plants.
On brackish or freshwater estuaries where they often winter, gadwalls concentrate on vegetation such as widgeon grass, eelgrass, muskgrass and pondweeds. In Pennsylvania, gadwalls are uncommon. They are considered non-breeding residents, although they have nested in Crawford and Butler counties. They breed mainly in the western United States, Canada and Alaska. Hens seek dense, dry weed cover, hiding the nest from above and all sides.