Multi-trait mimicry and the relative salience of individual traits

Abstract

Mimicry occurswhen one species gains protection frompredators by resembling an unprofitable model species. The degree of mimic–model similarity is variable in nature and is closely related to the number of traits that themimic shares with its model. Here, we experimentally test the hypothesis that the relative salience of traits, as perceived by a predator, is an important determinant of the degree of mimic–model similarity required for successful mimicry. We manipulated the relative salience of the traits of a two-trait artificialmodel prey, and subsequently tested the survival ofmimics of the different traits. The unrewarded model prey had two colour traits, black and blue, and the rewarded prey had two combinations of green, brown and grey shades. Blue tits were used as predators. We found that the birds perceived the black and blue traits to be similarly salient in one treatment, and mimic–model similarity in both traits was then required for highmimic success. In a second treatment, the blue traitwas themost salient trait, and mimic–model similarity in this trait alone achieved high success. Our results thus support the idea that similar salience of model traits can explain the occurrence of multi-trait mimicry.