Meeting Abstract

105.5  Wednesday, Jan. 7  Flight muscle function during takeoff, landing, and mid-flight, in the pigeon Columba livia BERG, Angela M*; BIEWENER, Andrew A; Harvard University aberg@oeb.harvard.edu

In order to achieve different modes of flight, such as takeoff and landing, a bird must move its wings differently. Variation in wing motion requires corresponding variation in activation and shortening patterns of the flight muscles. To explore variation in flight muscle function, we used EMG and sonomicrometry in the pectoralis, biceps, and triceps muscles of the pigeon Columba livia. To understand the effects of muscle function variation on wing motion, we coupled in vivo muscle recordings with high-speed video to record flight kinematics. The triceps, biceps, and pectoralis all showed small increases in length change during takeoff flight and during wingbeats prior to landing. In all wingbeats except the final landing wingbeat, the pectoralis and biceps tended to reach their shortest lengths simultaneously, reflecting the flexed wing posture observed at the end of downstroke. In the final wingbeat of landing, the pectoralis shortened less and the stroke amplitude correspondingly decreased. The biceps also shortened less in the final wingbeat, and continued to shorten after the pectoralis began to lengthen. The biceps was active during lengthening and remained active until after it began to shorten. This activation pattern may allow the production of high force at the elbow to accelerate the wing when it reverses direction at the end of the downstroke.