Greater scaup days. The down-covered ducklings are able to follow their mother in her search for food immediately after hatching. Greater scaup eat aquatic molluscs, plants, and insects, which they obtain by diving underwater. They form large groups, called "rafts", that can number in the thousands. Their main threat is human development, although they are preyed upon by owls, skunks, raccoons, foxes, coyotes, and humans. Greater scaup populations have been declining since the 1980s; however, they are still listed as a species of least concern on the IUCN Red List. The genus name "Aythya" is derived from the Ancient Greek "aithuia" which
Lesser scaup well as seeds and other parts of aquatic plants like sedges and bulrushes (Cyperaceae), "pondweeds", widgeon-grass ("Ruppia cirrhosa"), wild celery ("Vallisneria americana") or wild rice ("Zizania"). In winter, but less so in summer, other aquatic animals—crustacean, insect and their larvae and small fishes—form an important part of their diet. It has been reported that both the lesser and the greater scaup have shifted their traditional migration routes to take advantage of the presence of the zebra mussel ("Dreissena polymorpha") in Lake Erie, which was accidentally introduced in the 1980s and has multiplied enormously. This may pose a risk to these