Monarch Butterflies Navigate by Using the Sun as a Compass

Scouts and sailors may pride themselves on their abilities to navigate using the sun, but butterflies can do it too, scientists reported Wednesday. Tests on monarch butterflies showed they used the sun as a compass when flying from their fall breeding grounds in the eastern United States south to Mexico.

Evolutionary biologist Sandra Perez of the University of Arizona and colleagues threw off the internal body clocks of some butterflies by keeping them in the dark. In theory, that should throw the insects off track because the sun would appear to be in the wrong place for the time of day the butterflies thought it was. This was indeed what happened, the scientists reported in Nature. The result demonstrated that the butterflies were using the sun to navigate.