Lesser scaup in their first or second summer. The oldest known individual reached an age of over 18 years. Before the start of the population decline (see below), about 57% of the lesser scaup nests failed each breeding season because the female was killed or the eggs were eaten or destroyed. The average brood size of nests where eggs hatched successfully was 8.33 hatchlings. Although the lesser scaup has the largest population of any species of diving duck in North America, their population has been steadily declining since the mid-1980s, and reached an all-time low in the early 21sh century. During breeding
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