January 16, 2014
Researchers Discover Reasons For, Mechanics Behind V Formation Of Birds
redOrbit Staff & Wire Reports - Your Universe Online
By fitting data loggers onto a flock of birds, researchers from the Royal Veterinary College in London have discovered why the creatures typically fly in a distinctive V formation, according to research appearing in the latest edition of the journal Nature.
According to BBC News, Dr. Steven Portugal and his colleagues discovered that birds strategically position themselves in the optimal position, gaining lift from the bird in front of them by keeping close to its wingtip. Furthermore, they found that birds timed their wing beats in order to take advantage of the good air being produced.
Dr. Portugal’s team analyzed a flock of northern bald ibises, measuring the wing beats of all 14 birds during a 43-minute migratory flight completed entirely in V formation, AFP reporter Mariette le Roux explained. From the bird that was flying point, the ibises “fanned out to the back and side at an angle of about 45 degrees, and flapped their wings in phase.”
“The distinctive V-formation of bird flocks has long intrigued researchers and continues to attract both scientific and popular attention, however a definitive account of the aerodynamic implications of these formations has remained elusive until now,” the doctor said in a statement.
“The intricate mechanisms involved in V formation flight indicate remarkable awareness and ability of birds to respond to the wingpath of nearby flock-mates,” he added. “Birds in V formation seem to have developed complex phasing strategies to cope with the dynamic wakes produced by flapping wings.”
The researchers used special GPS biologging devices in order to keep track of the birds’ location, speed and direction during their migration, as well as the frequency of their wing-flaps. The data revealed that the spatial phasing of wing beats and the positioning of the birds helps them best utilize the beneficial upwash produced during the flight while also avoiding regions of detrimental downwash.
The phasing of the wing beats creates wing-tip path coherence between each of the individual birds, maximizing the capture of “good air” throughout the entire flap cycle, the study authors explained. Additionally, when they fly in the behind or streamwise position, they exhibit anti-phasing of their wing beats, avoiding exposure to “bad air.”
“Such a mechanism would be available specifically to flapping formation flight,” the college explained. “These aerodynamic accomplishments were previously not thought possible for birds because of the complex flight dynamics and sensory feedback that would be required to perform such a feat.”
The findings “once again remind us that animals are much more complicated… than we often give them credit for,” Kenny Breuer, a professor of engineering and ecology at Brown University that was not involved with the study, told USA Today. “They're reacting in very sophisticated ways to maintain these V formations.”
Researchers from the UK, Austria and Germany participated in the experiment, which involved endangered ibises that were reared by foster-caretakers at the Vienna Zoo. The birds were followed from Austria to Italy in a microlight plane so that the caretakers could learn their route, recording over 180,000 wing flaps during the flight.
“We are the first... to identify the aerodynamic interactions between individuals within a V, and to record the mechanism that birds in a V use to capture upwash (rising air),” Dr. Portugal told le Roux. He added that the results demonstrate the “remarkable awareness and ability of birds” to keep pace with their flock mates’ wing flaps, and that this type of knowledge could be used to help create fuel-saving flying machines.