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
A Bird came down the Walk other evil forces.Then the narrator offers the bird a piece of crumb,but the bird neglects it and then it flies away. Helen Vendler regards the poem as a "bizarre little narrative" but one that typifies many of Dickinson's best qualities. She likens the poet to a reporter observing a murderer in the act, and later, pretending fear that the murderer may be dangerous to herself and must be mollified by a "crumb". The bird takes flight and Vendler regards what follows - the description of the bird in flight - as "the astonishing part of the poem". Vendler notes that