This is a whistling duck that breeds in sub-Saharan Africa and much of South America.
This species is gregarious, and at favoured sites, the flocks of a thousand or more birds arriving at dawn are an impressive sight.
As the name implies, these are noisy birds with a clear three-note whistling call.
It has a long grey bill, a long head, and longish legs. It has a black neck and head, and distinctive white face that gives them their name. The back and wings are dark brown to black, and the underparts are black with a fine white barring on the flanks.
The neck is chestnut. Males and females have similar plumage. Juveniles are similar in color to adults, but have a much less contrasted head pattern.
Reference: Wikipedia