Birds make a variety of noises, including rhythmical, drawn-out songs and shorter communicative calls. A range of songs and calls from North American bird species can be heard at the Smithsonian website.
Research has linked the sounds that birds make to specific functions of communication. Bird songs appear to serve the twin purposes of attracting a mate or repulsing an enemy, while shorter calls have been linked with the sharing of information within bird groups, such as the whereabouts of food or danger.
Some birds, such as a number of parrot species and the mockingbird, imitate and adapt the sounds they hear in their environments.