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Desert Diary
Birds/Wing Slotting


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Watch a raven fly slowly by at close range. It's quite evident that the flight feathers toward the tip of the wing do not form a continuous surface, instead being separated by gaps called slotting. Yet, these slots must let air escape through them, which seems counterintuitive. So why are the feathers splayed out in that manner? Students of aerodynamics have answered the question. It seems that each of the so-called primary feathers acts as a separate airfoil—a miniature wing. This collection of feathers pushing against the air allows much more versatility than does a single surface. Slow, maneuverable flight is possible with wide slotting, while decreasing or closing the gaps gives an airfoil with lessened drag for faster, less maneuverable flight.

Slotting is just one of many ways that birds have evolved for versatility in flight. Short, broad wings; long, narrow, swept-back wings; wings with silencers—these and numerous other types anticipate almost everything that flight engineers have managed to come up with. Nearly everything, that is, except jet propulsion—one of the few flight innovations we humans can claim.
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Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.


Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.