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Conspicuous Camouflage

April 16, 2008

Scientists test whether predators really mistake the eyespots on the wings of some butterflies for real eyes.

Transcript

BOB HIRSHON (host):
Butterflies hide in plain sight…I’m Bob Hirshon and this is Science Update.

Some animals use camouflage to avoid predation. But for others, being conspicuous may be just as effective. Take, for example, eyespots on the wings of some butterflies. Scientists used to think the large eyespots made predators nervous. But a recent experiment by behavioral ecologist Martin Stevens from the University of Cambridge in England and his colleagues contradicts this idea. They compared the frequency of bird attacks on imitation butterflies that had markings of different shapes such as bars and squares and found that

MARTIN STEVENS (University of Cambridge):
They would be avoided equally as much as treatments which had a pair of spots which looked like eyes.

HIRSHON:
Instead, the birds avoided those faux butterflies with the largest overall markings. This suggests that predators are deterred by the conspicuousness of markings, rather than their shape, because conspicuous prey are often poisonous. I’m Bob Hirshon, for AAAS, the science society.