Avise's Birds of the World Knob billed Duck (Sarkidiornis melanotos) EcoRegistros Knob billed Duck eBird Portrait of knob billed duck (Sarkidiornis melanotos), Tanzania Photographic Print Panoramic Images AllPosters.com 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. The knob billed duck (Sarkidiornis melanotos) aka African comb duck, is found in tropical wetlands in Sub Saharan Africa, Madagascar and the Indian Subcontinent from northern India to Laos and extreme southern China.