Orientation Responses of Ring-Billed Gull Chicks: A Re-Evaluation

Abstract

The mean bearing for Ring-Billed Gull chicks tested in orientation cages correlates favorably with the direction in which they will head to reach the winter range. Previous studies indicated that geomagnetic cues alone were of importance in this process. Reanalysis of data from 3 500 trials has shown that under some conditions (1) directional shifts rather than disorientation may occur, and that (2) solar cues may be used as a supplemental source of information. Severe magnetic disturbance usually results in disorientation, regardless of sky conditions. Changes in apparatus design may significantly influence results, and this problem must be entertained during data interpretation.