It is an anatomical feature of the crane’s sternum that explains the exceptional power of its scream. When flying, Common Cranes (Grus grus) scream approximately every ten to fifteen seconds. A sonorous “krou krou”, it can be heard for miles around. Courtship is performed throughout the year, even outside the breeding season. Jumps with wings wide open, curtsies, pirouettes, runs, and neck undulations are accompanied by the usual screams from both partners. Pairs form for life and isolate themselves from the group to nest.