THE ORIENTATIONAL SALIENCE OF VISUAL CUES TO THE HOMING PIGEON

A potentially valuable method for investigating the role of visual lan dmarks in the familiar area map is to use an open-field arena food-sea rching task, allowing landmarks and the sun compass to be independentl y manipulated. In previous such experiments performed outdoors, homing pigeons, Columba livia, primarily used the sun compass rather than vi sual cues to locate the target goal. One possible reason for this resu lt may have been that the artificial two-dimensional landmarks provide d lacked salience, forcing the pigeons to rely on the sun compass. In this study the salience of two-dimensional visual cues indoors, where the sun compass was not available, was investigated. As pigeons were u nexpectedly unable to learn this task consistently, in a second experi ment a three-dimensional cue was added. The results suggest that: (1) pigeons are unable to use two-dimensional cues to locate the target go al consistently, when no other directional cues are available, but are able to use a three-dimensional cue in an otherwise identical task; ( 2) pigeons do not use non-visual cues (such as the magnetic compass) i ndoors to locate the target goal; and (3) the scatter in mean bearings often observed in clock-shifted pigeons is not caused by non-specific disturbance resulting from shifting the internal clock. The significa nce of our results is discussed in relation to the homing mechanisms u sed by pigeons at familiar sites. (C) 1997 The Association for the Stu dy of Animal Behaviour.