Birds in a flap reveal V-shape secrets

The mystery of why birds fly in V-formations has finally been solved with the help of lightweight sensors, fitted to the back of migrating birds.

A study of 14 Northern Bald Ibises shows they position themselves and flap their wings precisely to maximise the aerodynamic benefit of 'upwash' from the wings of the bird in front while avoiding 'downwash'

Dr Steve Portugal, Lead Researcher at the Royal Veterinary College, University of London, said: "A definitive account of the aerodynamic implications of these formations has remained elusive until now.

"The intricate mechanisms involved in V-formation flight indicate remarkable awareness and ability of birds to respond to the wingpath of nearby flock-mates. Birds in V-formation seem to have developed complex phasing strategies to cope with the dynamic wakes produced by flapping wings."

These aerodynamic accomplishments were previously not thought possible for birds because of the complex flight dynamics and sensory feedback required, researchers said.

The custom-built technology, funded by the Engineering and Physical Sciences Research Council, (EPSRC), captured the movements of every bird within the flock, recording its position, speed, and wing-flap during 43 minutes of migratory flight.

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."

UK Scientists worked together with the Waldrappteam, a conservation project which aims to reintroduce the Northern Bald Ibis into Europe. The Waldrappteam trained zoo-breed birds to follow a microlight in to teach the juvenile birds migration routes from Austria to Italy. It was during this migratory flight that the Royal Veterinary College team collected the data.

The research was published on the front page of the science journal, Nature.

More information:
"Upwash exploitation and downwash avoidance by flap phasing in ibis formation flight." Steven J. Portugal, Tatjana Y. Hubel, Johannes Fritz, Stefanie Heese, Daniela Trobe, Bernhard Voelkl, Stephen Hailes, Alan M. Wilson, James R. Usherwood. Nature 505, 399–402 (16 January 2014) doi:10.1038/nature12939

Provided by Engineering and Physical Sciences Research Council