Comb Duck Or American Comb Duck Sarkidiornis Sylvicola In Flight. Royalty-Free Stock Photo

It is one of the largest species of duck. Adults have a white head freckled with dark spots, and a pure white neck and underparts. The upperparts are glossy blue-black upperparts, with bluish and greenish iridescence especially prominent on the secondaries lower arm feathers. The male is much larger than the female, and has a large black knob on the bill.