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Turbulence gives birds a speed boost

Turbulence serves a source of energy that birds can use to their advantage, according to a new study led by Cornell University. Instead of hindering the ability to fly, the experts found that turbulence seems to serve as a speed booster for birds. 

While the flight of birds may appear easy and graceful to earthbound spectators, winged animals are actually navigating air flow that is structured, textured and constantly in flux, explained Professor Gregory Bewley, who led the team.

For the investigation, the researchers partnered with two groups, Conservation Science Global and Cellular Tracking Technologies. The scientists captured a female golden eagle in Alabama and equipped the bird with a solar GPS telemetry unit that weighed less than three ounces.

Over the next 17 days, the eagle migrated north along the Appalachian Mountains toward Canada. During this time, the GPS “backpack” transmitted more than 200 hours of data including location, altitude, and speed through cellular networks.

The team also obtained wind speed data from the National Centers for Environmental Prediction, and compared it to the eagle’s flight measurements. This allowed the experts to identify the bird’s various flying and non-flying behaviors.

The researchers identified a “highly irregular, fluctuating pattern” in the eagle’s accelerations. This pattern resembled the typical trajectories of particles in turbulent airflows.

For time periods ranging from 0.5 to 10 seconds, or approximately 1 to 25 wingbeats, the eagle’s accelerations were completely in sync with atmospheric turbulence.

Professor Bewley believes there are opportunities to harness the energy of turbulence, particularly for autonomous transport and small reconnaissance aircraft.

“If you could find a path in which every vortex is pushing you the right way, then obviously you get there a little faster with a little less energy,” said Professor Bewley. “We’re still working hard to understand turbulence by itself. I think it’s fascinating that there might be some practical empirical knowledge embodied in wildlife that we don’t appreciate yet.”

The study is published in the journal Proceedings of the National Academy of Sciences.

By Chrissy Sexton, Staff Writer

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