How Migrating Birds Fly in V-Formation: Aerodynamics Revealed

Why and how do birds fly in a V-Formation? Scientists have wondered just that and now, may have their answer. They've attached custom-built GPS and accelerometer loggers to flying birds on migration. The technique has allowed the researchers to uncover ground-breaking insights into bird flight formation.

"The distinctive V-formation of bird flocks has long intrigued researchers and continues to attract both scientific and popular attention, said Steve Portugal, one of the researchers, in a news release. However a definitive account of the aerodynamic implications of these formations has remained elusive until now."

In all, the researchers studied 14 juvenile birds that were hand-reared. They were then trained to follow a micro-light "mother ship" to teach them their historic migration routes. The birds were strapped with the GPSand the scientists then examined the process of their flight.

In order to achieve the V-formation flight, the birds employ specific mechanisms. First, there's the spatial phasing of wing beats when flying in a spanwise V position, creating wing-tip path coherence between individuals which maximize upwash capture through the entire flap cycle.

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

The second mechanism that the birds employ occurs when flying in a streamwise (behind) position. Birds exhibit spatial anti-phasing of their wing beats, creating no wing-tip path coherence and avoiding regions of detrimental downwash. This mechanism is specifically available during flapping formation flight.

The findings reveal a bit more about the intricate flight of birds. More specifically, it shows how these birds cope with the dynamic wakes produced by flapping wings. The research in particular is an excellent example of an international collaboration that shows that the birds can perform complex aerodynamic feats. The results could be useful in a variety of fields, such as aerodynamics and manufacturing.

The findings are published in the journal Nature.