male and female Tufted duck, (Aythya fuligula), Walthamstow Reservoirs, Greater London, United Kingdom, British Isles

The tufted duck (Aythya fuligula) is a small diving duck with a population of close to one million birds. 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 is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.