When a bird hits turbulence while flying, it can’t turn on the “fasten seatbelt” sign. Instead, new research shows that it tucks its wings to stabilize its flight.
Scientists were studying the flight of a captive Eurasian steppe eagle (Aquila nipalensis) when they noticed a curious behavior. While soaring, the bird would often briefly fold its wings before resuming its normal flight.
Called wing tucks, these behaviors are not new to scientists: In fact, one of the Wright brothers, Wilbur, coined the term while spending many hours watching bird flight to improve aircraft design in 1908. (See “Wright Brothers Flight Legacy Hits New Turbulence.”)
But the scientists began to wonder if the eagle’s frequent wing tucks somehow influenced its aerodynamics. So the team fitted the eagle with a customized, backpack-like harness equipped with a tiny, super-lightweight data recorder—actually a repurposed autopilot device from a drone aircraft. In this sense, the recorder served as the eagle’s black box, recording speed, altitude, pitch and roll, and a host of other information.
The researchers sent the bird on 45 flights through Brecon Beacons National Park in southern Wales, where they recorded 2,594 wing tucks. The data from their recorder revealed that the bird tucked its wings in response to atmospheric turbulence, according to the new study, published October 14 in Journal of the Royal Society Interface.