Common Cranes (Grus grus) fly with their necks and legs stretched out. When flapping, the wings create a small disturbance behind the bird. A sort of micro-vortex that rises and falls according to the rhythm of the wingbeats. The cranes line up one behind the other in a V formation and then fine tune their wingbeats. With this 45-degree positioning, they take full advantage of the upward swirl of movement of the birds in front of them. An intuitive knowledge of aerodynamics that allows them to save energy in flight.