CONTRIBUTIONS OF THE PROPATAGIUM TO AVIAN FLIGHT

Through flight experiments with live birds and computer modeling we de fine the aerodynamic contributions of the propatagium in avian flight. From flight trials we found that in House Sparrows, with all flight f eathers removed except for the distal six primaries, the loss of appro ximately 50% of the propatagium's projected area and its cambered prof ile produced a significant reduction in the distance a bird was able t o cover in flight. Removal of the secondary feathers, leaving six dist al primaries and an intact propatagium, did not have a noticeable affe ct upon flight. From the computer model which is representative of the bird wing's mid-antebrachial chord (cambered propatagium, symmetrical musculoskeletal elements, and flat secondary flight feathers), we fou nd that the propatagium: (1) produced the majority of the lift; (2) ha d a higher (relative to secondary feathers) production of lift in rela tion to its angle of attack, i.e., steeper lift-curve slope; and (3) p roduced more lift with a chord only 1/5 that of the feather subsection . We conclude that the cambered propatagium is the major lift generati ng component of the wing proximal to the wrist. (C) 1996 Wiley-Liss, I nc.