City pigeons may be jeered as flying rats, but aloft they're more like helicopters. That's the upshot of a new study of pigeons making aerial turns. The investigators netted common pigeons, Columba livia, in a parking garage, and aimed high-speed cameras at them as they slowly turned a corner. From the videos, the researchers then calculated the aerodynamic forces the birds produced to keep themselves aloft and moving. Unlike a rocket that simply swivels its jets, a pigeon doesn't turn by redirecting the forces it generates relative to its body. Instead, the bird realigns those forces by rotating its entire body, primarily by tipping its wings into the turn. A helicopter uses the same tipping strategy, lowering its nose to accelerate forward, for example. The study, posted today in the Proceedings of the National Academy of Sciences, also found that the turning pigeon's upstroke generates lift comparable to that produced by that super-aerialist the hummingbird—not bad for a laughingstock of the avian world.
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