Greater scaup to other diving ducks. The greater scaup forms large flocks, some of which can contain thousands of birds. When flocks are on flowing water, they will face the current, and as the ducks float backwards, some fly to the front of the flock to maintain position. Common predators of the greater scaup are owls, skunks, raccoons, foxes, coyotes, and humans. Greater scaup often find themselves entangled in fishing nets, thus large numbers of them drown in nets each year. Greater scaup can catch avian influenza, so future outbreaks have the potential to threaten greater scaup populations. Although the greater scaup
New Zealand scaup for twenty to thirty seconds and go down three metres to look for aquatic plants, small fish, water snails, mussels and insects. It is sometimes seen with the Australian coot ("Fulica atra"); it is thought that the scaup takes advantage of the food stirred up by the coots as they fossick for shrimps. It is found throughout both the North and South Islands of New Zealand in deep freshwater lakes and ponds. Unlike other members of this genus, the scaup is not migratory, although it does move to open water from high country lakes if they become frozen in winter.