KINEMATIC, AERODYNAMIC AND ANATOMICAL MECHANISMS IN THE SLOW, MANEUVERING FLIGHT OF PIGEONS

A high-speed (200 Hz) infrared video system was used in a three-dimens ional analysis of pigeon wing and body kinematics to determine the aer odynamic and anatomical mechanisms they use to produce force asymmetri es to effect a turn during slow (3 ms(-1)) flight, Contrary to our exp ectations, pigeons used downstroke velocity asymmetries, rather than a ngle of attack or surface area asymmetries, to produce the disparities in force needed for directional changes, To produce a bank, a velocit y asymmetry is created early in the downstroke and, in the majority of cases, then reversed at the end of the same downstroke, thus arrestin g the rolling angular momentum, When the velocity asymmetry was not re versed at the end of downstroke, the arresting force asymmetry was pro duced during upstroke, with velocity asymmetries creating disparate dr ag forces on the wings, Rather than using subtle aerodynamic variables to produce subtle downstroke force asymmetries, pigeons constantly ad just their position using a series of large alternating and opposing f orces during downstroke and upstroke, Thus, a pigeon creates a precise 'average' body position (e.g. bank angle) and flight path by producin g a series of rapidly oscillating movements, Although the primary loco motor event (downstroke) is saltatory, maneuvering during slow flight should be considered as a product of nearly continuous, juxtaposed for ce generation throughout the wingbeat cycle, Further, viewing upstroke as more than stereotypical, symmetrical wing recovery alters the evol utionary and functional context of investigations into the musculoskel etal mechanisms and the associated neural control involved in this uni que kinematic event.