Science: Guiding Clicks

Bats navigate the night by a natural system of echo sounding, much like the Navy's elaborately developed sonar (for sound navigation and ranging). They send out pulsed ultrasonic squeaks that bounce back from obstacles and tell them how they are going from point to point. Zoologist Donald R. Griffin of Harvard, an authority on bat navigation, has long suspected that birds living a batlike life (feeding at night and roosting in dark caves) may use a similar system. At the invitation of William H. Phelps Jr. of Caracas, he went to Caripe, Venezuela, to...

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