A frigate bird near the Galapagos IslandsFLICKR, HARVEY BARRISON
Frigatebirds spend weeks or even months at a time cruising above open ocean, spearing fish from the surface. Their voyages take them far from any place to rest, and the birds can’t swim, which has made their feats of endurance a biological puzzle.
Ornithologist Henri Weimerskirch of the French National Centre for Scientific Research (CNRS) and colleagues fixed GPS trackers, accelerometers, and heart rate monitors to frigatebirds to track their travels and energy expenditure. In a study published this summer (July 1) in Science, the researchers reported that the birds spent about as little energy soaring hundreds of miles every day as they would sitting at rest.
Their trick is to ride thermal currents upward for thousands of feet and then glide down while the ...
