The tufted duck (Aythya fuligula) is a small diving duck with a population of close to one million birds, found in northern Eurasia. The scientific name is derived from Ancient Greek aithuia an unidentified seabird mentioned by authors including Hesychius and Aristotle, and Latin, fuligo "soot" and gula "throat". The adult male is all black except for white flanks and a blue-grey bill with gold-yellow eyes, along with a thin crest on the back of its head. It has an obvious head tuft that gives the species its name. The adult female is brown with paler flanks, and is more easily confused with other diving ducks. In particular, some have white around the bill base which resembles the scaup species, although the white is never as extensive as in those ducks. The females' call is a harsh, growling "karr", mostly given in flight. The males are mostly silent but they make whistles during courtship based on a simple "wit-oo". The only duck which is at all similar is the drake greater scaup which, however, has no tuft and a different call. The tufted duck breeds throughout temperate and northern Eurasia. It occasionally can be found as a winter visitor along both coasts of the United States and Canada. . These ducks are migratory in most of their range, and overwinter in the milder south and west of Europe, southern Asia and all year in most of the United Kingdom. One individual has been reported as far south as Melbourne, Australia.