Redhead (bird) blue bill during the breeding season. The redhead is in the family Anatidae (ducks, swans, geese) and genus "Aythya" (diving ducks). There are currently no described subspecies of the redhead. The redhead and the common pochard form a sister group which itself is sister to the canvasback. This group is then sister to the monophyletic group consisting of the white-eyes (hardhead, Madagascar pochard, and the sister species ferruginous duck and baer's pochard) and scaups (New Zealand scaup, ring-necked duck, tufted duck, greater scaup, lesser scaup). The redhead is a pochard, a diving duck specially adapted to foraging underwater. Their legs
Lesser scaup be recognizable by the purple instead of green sheen of the head and a darker back. But this is unreliable because it varies according to light conditions, and these birds are often too far away from the observer to make out any sheen at all. The best trait—if the primary remiges are not visible—is the shape of the head: in the greater scaup drake, the forehead is usually quite massive, whereas the nape presents a smooth shallow curve and may appear almost straightly sloping. The lesser scaup drake presents the opposite shape, with a less bulging forehead and a nape