If you spend some time observing these fine birds, you will see them spontaneously, it seems, form small circles where alot of calling and flapping goes on. It's quite a burst of noise and activity. Young males? Family leaders? It starts with one or two stretching out their long necks and calling in a taunting manner and then others join in, it builds to it's highest level with the beating of the wings and then they all settle again.