Do you know Why do birds sing because Male birds sing for two reasons: to attract mates in the breeding season and to warm other males to keep out of their territory.
Birds use others cell to communicate whit one other. When flying together, geese cell to make sure that they stay in touch and adult penguins can recognize the voice of their own chick from among thousands in a colony.
Birds know instinctively how to sing but some species can learn to add new notes to their songs. Birds that are good at imitation, like starlings incorporate the sounds of car alarms in their songs and in Australia some superb lyrebirds have learned to imitate the noise of chainsaw.