Jan. 29 - Bird species that fly in a V-formation do so to conserve energy, according to scientists in the UK. In experiments with free-flying birds, researchers at the Royal Veterinary College in London answered a centuries-old question by demonstrating that birds like the Northern Ibis create a slipstream for their flock-mates to follow, thereby making flight more efficient. Jim Drury has more.
UPSOT: MICROLIGHT It's a question that has puzzled scientists for centuries - why do some bird species fly in a V-shaped formation? The answer is to save energy, according to researchers at Britain's Royal Veterinary College. Lead researcher Dr Steven Portugal attached custom-built GPS and accelerometer loggers to flocks of birds, and saw how they maximised the capture of what he calls, upwash. SOUNDBITE (English) STEVEN PORTUGAL, LEAD RESEARCHER AT THE ROYAL VETERINARY COLLEGE, UNIVERSITY OF LONDON, SAYING: "Upwash is this good air that comes off the wing tips when a bird is flying and we had theorised for decades, scientists had predicted, that birds could take advantage of this by flying in a V-formation shape, but actually what no-one had been able to do previously was to understand the mechanism by which that upwash could be captured. So what we found is the mechanism, these positive aerodynamic interactions that take place between individuals in a V, how that upwash therefore could be captured." Portugal's team worked with Austrian conservation group Waldarappteam, who were using microlight aircraft to teach captive Northern Bald Ibises their historic migration routes to Italy. Portugal's light-weight devices recorded precisely where each bird was within the flock, its speed, and how hard it flapped its wings. SOUNDBITE (English) STEVEN PORTUGAL, LEAD RESEARCHER AT THE ROYAL VETERINARY COLLEGE, UNIVERSITY OF LONDON, SAYING: "The loggers we've developed in our lab are really special because they have such accurate GPS with them, and this is the antenna here which measures the exact positioning of the bird within the flock, and what that means is we can accurately start to recreate for example V-formations or cluster flocks of pigeons by saying this individual was here, this individual was here, this individual was here. So that was the real step change that made us able to start answering some of these questions about flock dynamics." Colleague Dr Jim Usherwood says the research shows the remarkable awareness of birds to respond to a flock-mates' wingpath. SOUNDBITE (English) DR JIM USHERWOOD, WELLCOME TRUST SENIOR RESEARCH FELLOW, AND LECTURER AT THE ROYAL VETERINARY COLLEGE, UNIVERSITY OF LONDON, SAYING: "The idea about flight is what you have to do to stay up, to support your body weight, is to throw air down.......what a bird has to do is flap its wings gently...Of course when you're throwing air down there turns out to be a bit of a swirl around this downward air that's upwards, and if you can position yourself in the right bit of upwards air then you can get some kind of benefit." Portugal says the research, published in the journal Nature, could influence efforts to reduce fuel consumption among the next generation of unmanned vehicles. The team now plan to examine flock decision making - who takes charge of the migration as the birds make their historic journeys.