HIDDEN COLOR AVERSIONS IN DOMESTIC CLICKS TRIGGERED BY PYRAZINE ODORSOF INSECT WARNING DISPLAYS

ANIMAL signals are often 'multicomponent'(1-3), consisting of displays with several parts to allow exploitation of different senses, An exam ple is the courtship display of the peacock, which combines dashing mo vements with a noisy, shimmering show of his train feathers(4). Yet th e significance of multicomponent signalling is unknown. As a model mul ticomponent signalling system, we investigated the naming signals of t oxic insects, which often combine pyrazine odours with conspicuous col oration such as yellow or red(5-7). Here we demonstrate, in prey choic e experiments with birds, that pyrazine interacts with red and yellow to induce strong aversions to these aposematic colours that are not sh own in the absence of the odour. Pyrazine is shown neither to be inher ently aversive, nor to induce aversion to a non-aposematic colour, gre en. To our knowledge, this study provides the first evidence that the function of multicomponent signals can lie in hidden psychological res ponses produced by the interaction of their components.