Wandering albatrosses (Diomedea exulans) can fly thousands of kilometers to forage at sea—with barely a flap of their long, graceful wings. The secret to the birds' unflappable flight, it turns out, is a four-step soaring cycle that harnesses the energy of the wind. During a 3-month-long, first-of-its-kind field study at a breeding colony in the Kerguelen Islands in the southern Indian Ocean, researchers taped tiny, 100-gram GPS receivers between the wings of nesting birds, gathering 36 days' worth of flight data from 16 different birds. By measuring a foraging bird's position 10 times each second, the researchers discerned that each lengthy flight was made up of repeated cycles lasting about 15 seconds each and made up of four distinct phases, they report today in PLoS ONE. First, the bird would soar across the wind and slightly into it, climbing from just above the waves to a height of about 15 meters. At the peak of its flight path, the bird would turn to face downwind. Then, after soaring in that direction as far as possible, the bird would complete the cycle by turning to face across the wind, positioning itself for another swooping climb. Scientists designing robotic aircraft, the team suggests, might be able to learn a trick or two about energy-efficient flight from these birds.
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