Who has not marveled at the beautiful sight of birds migrating in a V pattern through the skies? They are a familiar and a lovely sight, but research to date has not come up with a sound explanation for why they do so. A team from the Royal Veterinary College has come up with some remarkable answers. They trained rare birds to migrate by teaching them to follow the lead of a microlight. By fitting data detectors on each bird they were then able to break down and examine the flight patterns of each one.
Among the revelations was the clear evidence that every bird gains “upwash” from the bird in front of it, and carefully positions itself to take every advantage of the movement of air. By monitoring and meticulously tracking every single wing flap of every member of the flock, the scientists could establish a pattern.
Flying in a V is optimal as every bird times its wing beat to take advantage of the lift that streams its way and this enable their heartbeat to go down, providing great energy-saving. The reduction in heartbeat had already been established in a study with pelicans, but this new work has unlocked more secrets regarding speed and positioning.
The intention of the project was to re-introduce the bald headed ibis back into Europe where it had become hunted out and thus was critically endangered. This meant that the birds had lost their intrinsic and intuitive understanding of their navigation route, and had to be re-trained to learn it again. The data loggers on the ibis showed up the intricacies of their aerodynamic skills.
Dr Steven Portugal, the lead researcher from the conservation project, based out of Walarappteam in Austria, explained how they were very aware and continually adjusting to the other birds in the flock. Whether a bird was flapping its wings or gliding along, it created a downward push of air under its wings. This “downwash” is bad for the bird behind. It pulls them down. However, as the air is tugged under, some comes up around the corners of the wingtips, and this is the “upwash.” The optimum place for each bird is to keep its own wingtip in the upwash of the bird it is following. To this end, they will all time each beat absolutely perfectly to catch this good air that propels them forward, almost like a free ride. With each and every wingtip in the upwash, every bird is maximized for efficient flight.
Professor of biomechanics at Oxford University, Adrian Thomas, echoes many people’s sentiments when he remarks,”V formations are so beautiful.” He sees useful ramifications for the unmanned aerial vehicle industry from this work by the Austrian team. Dr Portugal also says that the elucidation of this mechanism may now help these UAV companies to evolve better fuel saving machines.
Portugal thinks that what the birds can achieve is truly amazing, and “from a sensory point of view, it’s really incredible.” He has published his findings in the journal Nature. As he says in the opening paragraph of his results, bird flock V formations have been intruiging researchers and always attracted attention from both the scientific and the popular spheres. He and his colleagues have finally sourced accurate data for the long-held assumption that there are energy benefits to flying in formation.
The so-called “upwash exploitation” coupled with the avoidance of the downwash is the secret to the flap cycle and its astounding success. Finally, there is a clear explanation as to why birds choose to fly in V formations.
By Kate Henderson