Greater scaup faces numerous threats, the most significant challenge to their survival is habitat degradation caused by a mix of human development and runoff. Greater scaup, when moulting and during the winter, are threatened by escalated levels of organochloride contaminants. Oil and sewage pollution also threaten this duck. Since 80% of the greater scaup population winters in the urbanized part of the Atlantic Flyway, these ducks are subject to high levels of organic contaminates, along with increased levels of heavy metals in foods and habitat. A joint group of American and Canadian scientists researching scaup migration across the Great Lakes found that
Lesser scaup bird surveys, lesser and greater scaup are counted together due to the impossibility of identifying the species unequivocally when large numbers of birds are involved. Lesser scaup are thought to comprise slightly less than nine-tenths of the scaup population of North America. In the 1970s, the lesser scaup population was estimated at 6.9 million birds on average; in the 1990s it had declined to about half that number, and by the late 2000s it is estimated at 3 million individuals or less. Due to the wide breeding range and the fact that the rate of decline, though remarkable, is still