Effects of colour, shape, and pattern contrast of prey on discrimination learning in avian predators

Aposematism is a phenomenon in which noxious animals signal their unprofitability to predators by using conspicuous and contrasting visual signals. These visual signals are composed from several components, with the most important being bright colours and contrasting internal patterns. To compare the difficulty of several discriminative stimuli that consist with components of aposematic warning colouration in live animals, experiments were conducted with naive and adult Great Tits (Parus major). The Great Tits were presented with artificial prey, in the form of paper bugs, with the use of a sequential discrimination task; the bugs used differed in colour, shape or internal contrast. Each of the components were tested separately to ensure that the learned or unlearned discrimination task was dependant on the difficulty of the component. The results showed that the birds learned discrimination task when they could use colour or contrast as a cue but if the cue was shaped, they were not successful. These results support the hypothesis that the obvious discriminatory element was colour. Nevertheless, a surprising result emerged when using the discriminatory element of contrast as it was believed that birds are unable to learn the task if they can discriminate only by one contrast. This study not only..