“Life as a small bird is like being a human in Jurassic Park,” he says. “You’re constantly on edge, constantly wary of what can eat you, including hawks ten or twenty times your size.” No wonder birds have evolved numerous strategies for raising alarm. Magrath and his students have found that some birds signal danger with just their wings. Crested pigeons have specially modified wing feathers that produce distinct notes during escape from predators, prompting other birds to flee. Sometimes the warning isn’t a sound at all but the silence between sounds. When noisy, social birds like red-winged
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