Butterfly Wing Patterns May Confuse Predators in Flight

A study published in Nature reports that butterfly wing patterns, working together with the insects’ wingbeats, can create visual illusions that may make it harder for birds to track their speed and direction during flight. The researchers say the effect could disrupt an attacking predator’s aim, although the study did not test attacks by live birds. The team, led by researchers at the University of Exeter, compared the effect to the barber pole illusion, in which stripes on a spinning pole appear to move upward even though the pole is not rising. As butterfly wings clap together and separate during flight, their markings change angle and direction. The researchers’ account is that these shifting patterns can produce misleading motion cues that obscure the butterfly’s actual course. The idea emerged after researcher Jolyon Troscianko put slow-motion footage of a butterfly through a computer model of bird vision. The model indicated downward movement while the butterfly was moving upward. Troscianko said he first checked whether the result reflected a coding error before considering that the conflicting signals might confuse a predator.