"It is probably too costly for the blue tits to actually call the bluff because, in most situations, these eyes suggest that one of the blue tit's worst predators, an owl, is watching the bird," Vallin told Animal Planet News.
In the study, the researchers exposed peacock butterflies to wild-caught blue tits, opportunistic birds with strong insect-catching skills.
Vallin and colleagues chose peacock butterflies, expecting them to have strong abilities to evade predators as a result of their long exposure to natural enemies when they hibernate.
When resting, peacock butterflies only show the dark-colored ventral side of their wings. When disturbed, they produce a hissing noise and suddenly open the wings, exposing bright colors and four major eyespots.
Vallin tested the importance of eyespots, stridulation — the production of sounds by rubbing two body parts together — and the combination of both, by manipulating 54 butterflies to have either eyespots or to produce sound, or both traits neutralized.
