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| Abstract Title:
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| Angled and decelerating flight in the pigeon (Columba livia)
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| Graduate Student Presenter:
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Angela M. Berg
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| Name of the Author(s) and Affiliation(s):
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Angela M. Berg, Harvard University; Andrew A. Biewener, Harvard University
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Ascending or descending locomotion involves a change in potential energy and a corresponding change in power requirement. We sought to test if the mechanical power required for steady ascending or descending flight is a simple sum of the power required for level flight and the power necessary for potential energy change. Using high-speed video and pigeons trained to fly at varying angles, we found this hypothesis to be true, except for steep descents. We observed that there appeared to be a limit on the amount of potential energy that the birds could gain or dissipate per wingbeat.
Deceleration requires the rearward force to be greater than the forward force. To investigate deceleration in flapping flight, we studied landing in the pigeon. Stroke plane angle increased from negative during level flight to positive during landing, suggesting that the wings force air forward during landing. Preliminary PIV (particle image velocimetry) data support this hypothesis.
Flight muscles control wing movement. Using EMG (electromyography) and sonomicrometry in pigeons, we sought to describe how muscle function changes during landing flight. Until the final landing wingbeat, the pectoralis and biceps tended to reach their shortest lengths simultaneously, flexing the wing at the end of downstroke. In the final landing wingbeat, the biceps and pectoralis shortened less, decreasing stroke amplitude and wing flexion. The biceps was active during lengthening and remained active until after it began to shorten. This activation pattern may allow production of high force to reverse wing direction at the beginning of upstroke.
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