ocr: NONVOCAL CALLS Most birds call by using their voice, but others have evolved quite different ways of making sounds. Todo this, they use a variety of body parts,including their beak, feet, wings, and even individual feathers. Nonvocal calls are often made by the male birds of certain species to auract a mate during courtship displays. They also serve to assert the bird's ownership ofterritory and warn any possible rivals of its presence. SEE ALSO
