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Science 17 January 2003:
Vol. 299. no. 5605, pp. 402 - 404
DOI: 10.1126/science.1078237
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Reports

Wing-Assisted Incline Running and the Evolution of Flight

Kenneth P. Dial

Flapping wings of galliform birds are routinely used to produce aerodynamic forces oriented toward the substrate to enhance hindlimb traction. Here, I document this behavior in natural and laboratory settings. Adult birds fully capable of aerial flight preferentially employ wing-assisted incline running (WAIR), rather than flying, to reach elevated refuges (such as cliffs, trees, and boulders). From the day of hatching and before attaining sustained aerial flight, developing ground birds use WAIR to enhance their locomotor performance through improved foot traction, ultimately permitting vertical running. WAIR provides insight from behaviors observable in living birds into the possible role of incipient wings in feathered theropod dinosaurs and offers a previously unstudied explanation for the evolution of avian flight.

Flight Laboratory, Avian Studies Program, Division of Biological Sciences, University of Montana (UM), Missoula, MT 59812, USA. E-mail: kdial{at}selway.umt.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Precocial development of locomotor performance in a ground-dwelling bird (Alectoris chukar): negotiating a three-dimensional terrestrial environment.
B. E. Jackson, P. Segre, and K. P. Dial (2009)
Proc R Soc B
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Aeromechanics in aeroecology: flight biology in the aerosphere.
S. M. Swartz, K. S. Breuer, and D. J. Willis (2008)
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Mosaicism, Modules, and the Evolution of Birds: Results from a Bayesian Approach to the Study of Morphological Evolution Using Discrete Character Data.
J. A. Clarke and K. M. Middleton (2008)
Syst Biol 57, 185-201
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Feather Quill Knobs in the Dinosaur Velociraptor.
A. H. Turner, P. J. Makovicky, and M. A. Norell (2007)
Science 317, 1721
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Aerodynamics of wing-assisted incline running in birds.
B. W. Tobalske and K. P. Dial (2007)
J. Exp. Biol. 210, 1742-1751
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Locomotor kinetics and kinematics on inclines and declines in the gray short-tailed opossum Monodelphis domestica.
A. R. Lammers, K. D. Earls, and A. R. Biknevicius (2006)
J. Exp. Biol. 209, 4154-4166
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Structure and function of hindlimb feathers in Archaeopteryx lithographica.
N. Longrich (2006)
Paleobiology 32, 417-431
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Terrestrial locomotion of the New Zealand short-tailed bat Mystacina tuberculata and the common vampire bat Desmodus rotundus.
D. K. Riskin, S. Parsons, W. A. Schutt Jr, G. G. Carter, and J. W. Hermanson (2006)
J. Exp. Biol. 209, 1725-1736
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The origin of the avian flight stroke: a kinematic and kinetic perspective.
S. M. Gatesy and D. B. Baier (2005)
Paleobiology 31, 382-399
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Mechanics of wing-assisted incline running (WAIR).
M. W. Bundle and K. P. Dial (2003)
J. Exp. Biol. 206, 4553-4564
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Science. ISSN 0036-8075 (print), 1095-9203 (online)