The mystery of why so many birds fly in a V formation may have been solved.

Scientists from the Royal Veterinary College in London fitted data loggers to a flock of rare birds that were being trained to migrate by following a microlight.

This revealed that the birds flew in the optimal position - gaining lift from the bird in front by remaining close to its wingtip.

The study, published in the journal Nature, also showed that the birds timed their wing beats.

Here, Dr Steven Portugal from the Royal Veterinary College describes the findings and the unique bird-training conservation project that made it possible.

Ibis footage courtesy of Waldarappteam. Video journalist: Victoria Gill