HEDRICK, TL; Harvard University, Cambridge MA: Low-speed maneuvering flight in the rose-breasted cockatoo

Maneuvering flight has long been recognized as an important component of the natural behavior of many bird species but has been the subject of little experimental work. Here I examine the kinematics and neuromuscular control of turning flight in the Rose-breasted cockatoo (Eolophus roseicapillus, n=6), testing predictions of maneuvering control based on aerodynamic theory and prior kinematic analysis. Six wild caught cockatoos were trained to navigate between two perches placed in an L-shaped flight corridor, making a 90-degree turn midway through each flight. The corridor, constructed of lightweight netting, was 1 m wide by 2.2 m high with one 2 m and one 3 m segment forming the L. Flights were recorded with 3 synchronized high-speed video cameras placed outside the corridor, allowing a 3D reconstruction of flight kinematics through the turn. I simultaneously collected electromyography recordings from bilateral implants in the pectoralis, supracoracoideus, biceps brachii and extensor carpi ulnaris muscles. The cockatoos maneuvered using flapping, banked turns with an average turn radius of 0.86 m. Bank angle was established in one shallow wingbeat at the start of each turn and then maintained until the turn was complete. Based on prior studies of avian maneuvering I hypothesized that differential timing of activation between the two pectoralis muscles would control turning. However, the recorded neuromuscular activity patterns suggest that the bank angle and turn were initiated and then maintained by differential activation intensity during downstroke between the two biceps brachii muscles, resulting in differences in wing extension and presumably aerodynamic force production. Thus, in avian flight the functions of flight power versus turning and control of direction may be handled by separate neuromuscular components.