How do birds sing
The songs and calls are imporatant methods of communication among birds. They sing to attract mates in the mating season to warn other birds of any incoming danger from predators and to establish danger from predators and to establish their home territories or nesting area. The bird calls aer usually distinctive and vary from species to species. This distinction hepls the birds to identify the calls meant for them. Among all the specise of the singing birds the male bird is usually the singer. It sings to attract the female bird. The sons of nightingale produce the best musical effects and other birds do not match it in comparision. The mocking bird has its own harsh call but can imitate the songs of other birds. Crow has a very crude voice. Apart from singing birds make other types of calls call for sending alarm singnals for food or calling their parent call in an aggressive or hostile mood etc.
A few birds such as pelicans and cormorants are voiceless. The singing birds belong to the suborder oscines. Their vocal cords are located in a special box, the syrinx at the base of the windpipe where it divides into two bronchi. The syrinx has a bony structure and form a sound-box within which membranes vibrate when the bird exhales. This produces varying notes in the birds voice. The structure of syrinx varies from species to species and till now seven different types have been recognised. The song of the birds have a pitch of about 4300Hz which is above the hightest note of a piano. Intensity of the calls of any single birds vary from the deep-pitched hoot of owls to the very high notes of small birds which are scarcely audible to the human ear.