Wing-Assisted Incline Running and the Evolution of Flight

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.

[1]  N. Pierce.  Origin of Species , 1914, Nature.

[2]  P. P. Gambari︠a︡n.  How mammals run : anatomical adaptations , 1974 .

[3]  Ostrom Jh,et al.  Bird flight: how did it begin? , 1979, American scientist.

[4]  Russell P. Balda,et al.  The Physics of Leaping Animals and the Evolution of Preflight , 1983, The American Naturalist.

[5]  Hans-Joachim Gregor,et al.  The beginnings of birds: Proceedings of the International Archaeopteryx Conference, Eichstätt, 1984. M.K. Hecht, J.H. Ostrom, G. Viohl and P. Wellnhofer (Editors). Jura Museum, Eichstätt, 382 pp. DM 90.00 , 1988 .

[6]  F. Jenkins.  The Evolution of the Avian Shoulder Joint , 1993 .

[7]  F. Maytag.  Evolution , 1996, Arch. Mus. Informatics.

[8]  A. Feduccia.  The origin and evolution of birds , 1996 .

[9]  Tobalske,et al.  Flight kinematics of black-billed magpies and pigeons over a wide range of speeds , 1996, The Journal of experimental biology.

[10]  L. Chiappe,et al.  The origin of birds and their flight. , 1998, Scientific American.

[11]  Adrian L. R. Thomas,et al.  On the origins of birds: the sequence of character acquisition in the evolution of avian flight , 1999, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[12]  Phillip Burgers,et al.  The wing of Archaeopteryx as a primary thrust generator , 1999, Nature.

[13]  Johannes Helder,et al.  Enzymology: Degradation of plant cell walls by a nematode , 2000, Nature.

[14]  S. Olson.  New Perspectives on the Origin and Early Evolution of Birds. Proceedings of the International Symposium in Honor of John H. Ostrom , 2002 .