In the hotly debated matter of bird-tail aerodynamics, the first wind tunnel measurements indicate that the prevailing theory may be wrong.
The basic avian tail has the triangular shape of supersonic planes like the Concorde, explains Jeremy Rayner at the University of Leeds in England. Since the early 1990s, dozens of ornithology papers have therefore drawn on the mathematics of these delta-wing aircraft. Biologists have argued over how much of the shape of a bird's tail comes from aerodynamics and how much from males' need to bedazzle females.
Rayner and his colleagues recently worked out a way to test avian delta-wing theory in a wind tunnel. Their data agree with the predictions of lift from an isolated tail, says Rayner. Howev