ocr: ALARM CALLS An alarm callisa burst ofsound that birds use to warn one another of approaching danger. Many species have two typesof alarm calls. They use repeated notes to warn of - danger on the ground anda single high- pitched sound to warn of danger overhead, such as a bird ofprey. Uniquely, alarm calls are understood by different species ofbirds. Ifal blackbird gives an alarm call, many other small birds are instantly alerted. SEE ALSO
