Great bustard (Otis tarda)
Great bustards can reach the weight of 17 kg, therefore they belong to the heaviest capable of flight birds on our planet. Their courtship is a real spectacle: the male bustard turns his wings upside down and also the bottom side feathers appear on top, he bends his neck, inflates his pouch, stretches and fans his long tail-feathers. In the end no one knows where is the front and where is the back. From a distance he looks totally changed, like a big feather ball or a huge blossomed flower. During the courtship his heart rate increases up to 900 beats a minute. The cocks then fight against each other, pushing the rival away and attacking the opponent with their beaks, often leaving some feathers during this. While the courtship proceeds silent, great bustards only produce a remarkable nasal-barking call used to alarm their conspecifics.