Date of Award:

5-1-1978

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Department name when degree awarded

Life Sciences:Biology

Committee Chair(s)

Keith L. Dixon

Committee

Keith L. Dixon

Committee

Barrie Gilbert

Committee

Ivan G. Palmblad

Abstract

The Chorus Girl Hypothesis (CGH) is presented to explain the rapid transfer of information through a flock during synchronous maneuvers. The primary feature of the hypothesis is that flock members receive information concerning the maneuver in advance of the leading edge of the maneuver wave. This advance warning allows flock members to time their own execution of the maneuver to coincide with the arrival of the maneuver wave, essentially eliminating the relatively large time lags that would be associated with a neighbor-to-neighbor transfer of information. Predictions from the CGH and the alternative Quick Reaction Hypothesis are tested. Observations suggest 11 characteristics of synchronous maneuvers in dunlin (Calidris alpina) flocks. 1. Flocks do not have a permanent (or semi-permanent) "leader." 2. Synchronous maneuvers are initiated by birds on the periphery of the flock. 3. Synchronous maneuvers are initiated by any flock member making an abrupt turn toward the flock. 4. Synchronous maneuvers proceed through the flock on a "no questions asked" basis. 5. Members of high density flocks time their execution of the maneuver to coincide with the arrival of the leading edge of the approaching maneuver wave. 6. Members of low density flocks time their execution of the maneuver so that the resulting distance to their neighbors (on the side of initiation) is decreased. 7. Flock members do not shuffle positions. 8. The apparent complexity of some synchronous flocking is created by a series of simple maneuvers, entailing only unidirectional changes. 9. The basic communication system used during synchronous flocking is visual. 10. The evolution of synchronous flocking did not require the acquisition of special abilities. 11. The primary function of synchronous flocking is to provide protection from predators. The power of the CGH is demonstrated by its ability to explain a variety of previously baffling observations.

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