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
Greater scaup 100% of female greater scaup, and 77% of female lesser scaup, had escalated levels of selenium in their bodies. Selenium is an occurring semimetallic trace element that occurs naturally in some soils and minute amounts are necessary for animal life. However excessive selenium can cause reproductive harm and is highly toxic. On their migration across the Great Lakes, greater scaups are at risk of ingesting selenium by eating the invasive zebra mussels, which can render a hen infertile. This sterilization of hens is causing the population to decrease. In a study of 107 scaup, they all had traces of iron,