Wild birds prefer to eat the more familiar of artificial morphs that are similar in colour

Abstract

Colour polymorphisms in prey species can be maintained if predators preferentially hunt for common morphs. This hypothesis was tested in sixteen experiments by presenting “populations” of pastry prey to wild birds in their normal surroundings. The artificial morphs were more similar in appearance than those used in previous experiments. Groups of birds were trained on one colour and then presented with populations with the familiar and an unfamiliar colour in equal proportions. The birds were then trained on the second colour and again given an equal choice between the two. In eight of the experiments the birds were also presented with “1:1” populations before the first session of training. Overall, there was good evidence that the birds preferred the familiar colour after the first training, and this effect was less marked after the second training.