Orientation behavior of Ring-billed Gull chicks and fledglings

TitleOrientation behavior of Ring-billed Gull chicks and fledglings
Publication TypeJournal Article
Year of Publication1969
AuthorsSouthern WEdward
JournalThe Condor

294 Ring-billed Gull chicks were used in orientation cage experiments. Over half (57.8%) of the chicks indicated preferences for headings of E, S, or SE, which correspond to the primary fall migration routes for members of the Rogers City, Michigan, population. Response patterns of experimental chicks resembled those of adults used in homing trials. During clear skies 61.9% of the chicks selected S, E, or SE. Under a complete overcast 71.6% of the birds showed preferences for these headings. The Rayleigh Test was applied to the circular distributions discussed in this paper. Selection of E, S, and SE headings decreased as the intensity of magnetic disturbances increased. However, only mild intensity magnetic storms were experienced during these experiments and the results are, therefore, inconclusive. The extent of correlation between fluctuations in the earth's magnetic field and orientation behavior by gull chicks has reopened the possibility of this type of cue being associated with the apparently innate directional preferences. Limited evidence also exists which suggests that topographical clues of some type may influence chick orientation behavior. 56 juvenile ring-bills were released in homing trials and about half (51.8%) selected E or SE courses during their maiden flight.