Mergellus albellus
A small and compact duck, more resembling a Goldeneye than other sawbils. Small bill and steep forehead. Male almost completely white, with black mask and fine black markings. In flight the dark wings gives it a more black and white appearance. Female or immature may be mistaken for other small ducks, but combination of brown upper head and white lower head is unique among WP-ducks. Body brownish grey. White patch on wing coverts prominent in flight in both sexes. Groups fly in loose lines, not bunches.
Mostly quiet except when displaying, and even then difficult to hear. Male: an ascending, froglike, rattling pulse of clicks. Also various grunting sounds. Alarm call a harsh "Kraaa".
Wikipedia: map (se also Xeno-canto below)
Birdlife ecology
