Eyespot peek-a-boo: Leaf rolls enhance the antipredator effect of insect eyespots.

Abstract

Animal colour patterns are often accompanied by specific, synergistic behaviours to most effectively defend prey against visual predators. Given the inherent context-dependence of colour perception, understanding how these colour-behaviour synergies function in a species' natural environment is crucial. For example, refuge-building species create a unique visual environment where most (or all) of the body is obscured unless closely inspected. How these built environments affect the perception of defensive colour patterns by predators is not well understood. Using artificial caterpillars that resemble a refuge-building species with conspicuous markings (Papilio troilus; Lepidoptera: Papilionidae), I tested the hypothesis that leaf rolls amplify the antipredator effect of this species' eyespots. I compared wild avian predation rates on 659 artificial swallowtail-like caterpillars from four treatment groups: eyespotted and non-eyespotted, and presented in leaf rolls or on open leaves of live host plants. In support of my hypothesis, eyespots only reduced predation for larvae in leaf rolls. On open leaves, eyespots had no antipredator effect. I also found that leaf rolls reduced predation in general for both eyespotted and non-eyespotted prey. These results highlight the importance of considering relevant behaviours in studies of animal coloration whenever possible, including behaviours that influence colour perception indirectly (e.g. through habitat use or modification).