VOA常速英语:Researchers: Birds Know Flying in V-Formation is Energy-Efficient

Scientists at the Royal Veterinary College in London have solved a centuries-old puzzle: why do some birds fly in a formation resembling the Latin letter V. Using modern technology, they confirmed that it's all about conserving energy.

Most drivers know that following a large truck saves gas because the truck is pushing a lot of air around it, creating a partial vacuum behind it, so the car encounters less resistance.

According to Steven Portugal, a researcher at London’s Royal Veterinary College, birds knew that long before humans did.

Using a flock of Northern Bald Ibises, Portugal and his team attached small devices to the back of each bird - a GPS navigation device and an accelerometer, to track wing movements. The recordings showed that the birds were able to use the upward airstream created by the wingtip of the bird just in front of it.

“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," said Portugal.

With the help of the Austrian conservation group Waldarappteam and its microlight aircraft, the British scientists followed the birds on their migration to Italy.

The GPS devices were so precise that they recorded in real time the position and speed of each bird within the flock, while the accelerometers captured how fast and hard each bird flapped its wings. The scientists recreated their movements in a computer.

Royal Veterinary College professor Jim Usherwood says they were impressed at how each bird was able to respond to the movement of the one just in front.

“If you can position yourself in the right bit of upwards air, then you can get some kind of benefit," said Usherwood.

Scientists plan to study how the birds decide who takes charge of the flock on their annual migrations across Europe.