White-winged duck is one of the largest species of duck. 35 in and wingspan is 60 in. Males weigh 4 kg, while females weigh 3 kg. The most noticeable feature on adult birds, is the dark body contrasting with a whitish head and neck. Males have mostly dull yellowish bill, blackish mottling on the head and upper neck, white lesser median coverts and inner edges of tertials and bluish-grey secondaries. In flight, white wing-coverts contrast with the rest of the wings. Females are smaller and usually have more densely mottled head and upper neck. The juvenile is duller and browner.