The Kori bustard is the heaviest flying bird of Africa, and probably of the world. Males are bigger than females, and may weigh up to 40 lb. Just like its main competitor about "the heaviest flying bird," the Great bustard (Otis tarda), it features an extraordinary mating behavior. It hold its head backwards, with an erect crest and inflated gular pouch, forming a white "foam bath balloon." Furthermore, its tail is raised upwards and forwards onto its back, forming a white, fluffy "feather-duster." The male with the most spectacular performance is of course the one that will mate with the females.