Knob billed Duck Closeup female knob billed duck or African comb duck (Sarkidiornis melanotos) perched on wood stake. The male has a large black knob on the bill but not the female Stock Photo Adobe Knob billed duck or African comb duck Sarkidiornis melanotos Stock Photo Alamy This bird wears its crown not of feathers, but of horn. The Knob billed Duck (Sarkidiornis melanotos), also known as the Comb Duck, is one of the most unmistakable waterfowl in the world.