Mystery of why birds fly in V format ?

  

The V formation greatly boosts the efficiency and range of flying birds, particularly over long migratory routes.
All the birds except the first fly in the upwash from the wingtip vortices of the bird ahead. 

The upwash assists each bird in supporting its own weight in flight, in the same way a glider can climb or maintain height indefinitely in rising air. In a V formation of 25 members, each bird can achieve a reduction of induced drag by up to 65% and as a result increase their range by 71%. The birds flying at the tips and at the front are rotated in a timely cyclical fashion to spread flight fatigue equally among the flock members.

Scientists used a microlight plane to show hand-raised birds their ancestral migration route from Austria to Italy. A flock of 14 juveniles carried data loggers specially built by Usherwood and his lab. The device’s GPS determined each bird’s flight position to within 30 cm, and an accelerometer showed the timing of the wing flaps.

Professor David Delpy, chief executive of the Engineering and Physical Sciences Research Council which funded the study, said: "This is a fascinating piece of research, providing a scientific answer to a question that I suspect most people have asked themselves - why do birds fly in formation? The results will prove useful in a variety of fields, for example aerodynamics and manufacturing."