The mystery of the V-formation

Seeing birds fly in a V is impressive. Theory has it that flying in this formation saves energy because they keep each other out of the wind. The birds take turns flying at the front.
A group of French and German scientists conducting very precise research on a flock of ibis flying in a V-formation discovered that the birds were much better experts in aerodynamics than was previously thought. The research, published in Nature, focused on 14 ibises fitted with sensors. Each bird’s position, speed and wing-flapping was measured during a 43-minute free flight. In a V, ibises make use of the vortices produced by the bird directly before it. When a bird flaps its wings down, it pushes the air down and creates a vortex. The air behind the bird comes back up, and even farther behind, back down again. The vortex looks like a wave in which the air moves upwards and downwards. Ibises are careful to move along with the vortices, flapping their wings upwards when the air moves upwards and downwards when the local vortex flows downwards. Much to the research team’s amazement, the birds time the beating of their wings very precisely.