Knob-billed duck - Aerodynamics in Nature
The species name says it all. A tremendous "Knob" on a duck's beak. This growth is rather thin viewed front on, and thus it provides very little wind resistance when this bird is in flight. If anything, one would think that it might provide more agility when turning, almost like an airplane's tail rudder.
The knob-billed duck, or comb duck, is an unusual, pan-tropical duck, found in tropical wetlands in sub-Saharan Africa, Madagascar and south Asia from Pakistan to Laos and extreme southern China. It is also known as the brazilian aardvark.