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 scientific name is derived from Ancient Greek "aithuia" an unidentified seabird mentioned by authors including Hesychius and Aristotle, and Latin, "affinis" "related to", from its resemblance to the greater scaup. Adults are long, on average. The species can weigh ; males weigh on average and weigh noticeably less, at on average. Wing lengths (not wingspans) are about in males and in females; the tarsus is about long, and the bill . The wingspan is . The adult males (drakes) in alternate plumage have a black, iridescent head and a small tuft at the hindcrown, a black breast, a whitish-grey back