Hummingbirds arent known for their power-lifting prowess. But researchers nevertheless put nearly 1,000 Peruvian hummers through lifting trials and flight tests over a two-year stretch in order to find out how their flying abilities are affected by the lower oxygen and thin air of higher elevations.
The results, which appeared this week in the Proceedings of the National Academy of Sciences (PNAS) Online Early Edition, show a clear decline in hummingbirds lifting ability with altitude, not unlike that seen in athletes competing at high elevations.
What this means for hummingbirds is less reserve power for the bursts of flight needed to chase off competitors or escape from predators, said researchers from the University of California, Berkeley, and the California Institute of Technology. "The costs of hovering flight are the same across elevations because hummingbirds compensate by having larger wings and by having a larger stroke amplitude," said study leader Douglas Altshuler, a postdoctoral fellow at Caltech. "However, that compensation doesnt come for free. They dont have as much excess power at high elevations as they do at low elevations."
Robert Sanders | EurekAlert!
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