A team of international researchers has discovered how birds manage to fly in such perfect formation.

The scientists found that through a complex hierarchy of leadership, each bird contributes to decisions about the movement of the flock.

Until now there were two theories about what governs the movement of a flock; either it fell to a leadership group of one or more birds, or it was an egalitarian system with each bird contributing to the decision.

But by attaching GPS devices to pigeons, the study found every bird plays a part.

“There was a kind of hierarchy of leadership within the group which means that in fact every individual did seem to have an input into what the flock did, but the weighting of their influences varied according to what the rank of the bird was within the flock,” Dora Biro from Oxford University’s Department of Zoology said.

“So some birds tended to do more leading than others.”

But the researchers did not find out what determines where in the hierarchy each bird sits.

“That’s something that we would very much like to extend this current work to,” Dr Biro said.

What is clear though is that every bird in the flock plays a leadership role.

“For instance, even the ones lower down the chain are responded to, are followed by the ones that are even further down the chain than they are,” Dr Biro said.

“So in fact, this is kind of what we mean by every individual having a vote because every individual has some contribution, can have some contribution to what the flock does.

“But how much they influence is ultimately determined by how far down the chain they are.”

The study, published in Nature magazine, also found the group’s leaders are likely to be in the front of the flock.

It also found that because birds prefer left-eye vision, those with an inferior standing tend to be positioned to the right.

Teeny GPS

The study involved strapping tiny GPS devices to each of the birds’ backs.

“We fitted them with kind of a cloth backpack that the GPS just slotted into,” Dr Biro said.

“These devices recorded the position of the birds with very high temporal resolution so we had positional fixes every 50th second. So every 0.2 seconds we knew where each of the birds was.

“And from the kind of shift from one fix to the next we could work out which bird was the kind of first one to make a turn and which of the others followed.”

Dr Biro is also interested if finding out whether this discovery applies to other animals that flock or herd.

“We’d have to go and track other species with a similar kind of accuracy, spatial and temporal accuracy that we managed to track these pigeons with,” she said.

“But you could think of other scenarios where groups face a kind of collective decision-making problem.”