Aythya fuligula (Tufted Duck)

6/12/17 Leeds Castle, Kent, England: 

LIFE LIST NOTES:

COMMON NAME: Tufted Duck

SPECIES: Aythya fuligula

FAMILY: Anatidae (Ducks, Geese & Swans)

LIFE LIST DATE: 6/12/2017

LOCATION: Leeds Castle, Kent, England, UK

From Wikipedia:

The adult male is all black except for white flanks and a blue-grey bill with gold-yellow eyes. 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 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. They form large flocks on open water in winter.