Calls of Nestling Chaffinches Fringilla coelebs: The Use of Two Sound Sources

To investigate the early development of vocalizations in chaffinches Fringilla coelebs a series of daily observations was made on a single nest from a few days prior to hatching until the last chick fledged. Sonograms were made of over 300 calls recorded from nestlings between the ages of 2 and 13 days. The development of the structurally complex vocalizations of older nestlings from the simpler calls of younger chicks is described and the ontogeny of the independent use of two sound sources is discussed.