Doing math on the fly, birds form the flying V for efficiency

Markus Unsold

Across the globe, hundreds of species of birds can be seen flying in V formations. We have long suspected that these formations might help birds fly with less effort, but the precise mechanics of this phenomenon have remained unknown—until now.

Expending less effort in long flights can be the difference between life and death for migratory birds. Higher efficiency saves precious fuel needed for journeys that can often be thousands of kilometers long. Cyclists in the Tour de France know this well. These cyclists ride in a group called the peloton, where the leader plows through the onrushing air while teammates riding behind him burn fewer calories. After some time, the leader swaps places to spread out the effort among the group.

Just like cyclists, it might seem intuitive that birds do the same when flying in a V formation. But flying is complicated by the fact that birds flap their wings, which changes how the air flows around them. Aerodynamic theory predicts that birds should save energy if they carefully adjust their position and flapping speed in a formation. This made some scientists question whether birds have the required sensory precision to achieve this feat in mid-air.