Juvenile greater scaup look similar to adult females. The type species is the greater scaup. Along with the aerial population surveys, there is a banding program for the greater scaup. Common predators of the greater scaup are owls, skunks, raccoons, foxes, coyotes, and humans. Greater scaup are a popular game bird in North America and Europe. During the summer months, the greater scaup will eat small aquatic crustaceans. In the fall, greater scaup populations start their migration south for the winter. Greater scaup are rated as a species of least concern by the IUCN Redlist. The adult greater scaup is long with a wingspan and a body mass of . The greater scaup dive to obtain food, which they eat on the surface. The greater scaup forms large flocks, some of which can contain thousands of birds. Greater scaup, black ducks, mallards, and Canada geese are the most abundant wintering birds. Greater scaup eat aquatic molluscs, plants, and insects, which they obtain by diving underwater.