some other animals use sound and the ability to hear. Birds, as we know, make a wide variety of sounds-fromcheeps and chirps to hoots and caws-all understandable by their own kind. Whales, too, seem to communicate by sound. According to some scientists, they sing 'songs' which other whales can hear many kilometres away! While the scientists are uncertain what the songs mean, they have no doubt the whales use them to talk to each other.