15. Long-crested Eagle The only eagle on our list is one of the smallest but commonest and most easily identified eagles in East Africa. Perched prominently on the top of a tree, usually the same tree, with its floppy crest blowing in the wind, it looks entirely black. In fact, though, its yellow legs are sheathed in smart white leggings and the wings have white patches, or ‘windows’ visible in flight. These are good for identification when you are looking from underneath and without sight of the crest: white windows in black wings. Like most eagles and large soaring birds, such as Marabou storks and vultures, this bird has at the end of the wings individual feathers protruding outwards like fingers. They perform an important function, which has been imitated by aircraft designers. Wings work, of course, because the aerofoil shape, whether on birds or planes, pushes the air above the wing upwards, creating a vacuum which pulls the wing, and the bird or plane, upwards. But that happens all along the wing and at the end, where there is no wing, this results in turbulence which creates drag. The ‘fingers’ disrupt that turbulence, as do those upturned fins at the end of aeroplane wings. Birds of AFRICAMA House 34 Birds of AFRICAMA House 35