Tufted Duck
Aythya fuligula

A fairly common diving duck in winter, but not as common as a resident. The males are a striking glossy purple-black and white with a long tuft from the back of the head. Some are very shy, others very tame, depending on location. The females are browner and have shorter tufts.
 

Tufted Duck male  Tufted Duck male

Tufted Duck female  Tufted Duck female

1: Black Swan Lake, Dinton Pastures LNR, 02/03/2007.
2-3: Radipole Lake RSPB, 26/01/2006.
4: Radipole Lake RSPB, 23/01/2007.