Structural Change of Begging Vocalisations and Vocal Repertoires in Two Hand-raised Australian Passerines, the Little Raven Corvus mellori and White-winged Chough Corcorax melanorhamphos

Abstract

Change in vocal structure during development was investigated in two large Australian passerines, a corvid, the Little Raven Corvus mellori and a corcoracid, the White-winged Chough Corcorax melanorhamphos. Begging calls in both species were harsh vocalisations covering a wide frequency range. The major ontogenetic change in begging call structure was in pulse duration. Little Raven begging calls increased in pulse duration with increasing age while White-winged Chough begging calls decreased in duration. In both species pulse duration of begging calls gradually approached the duration of other vocalisations such as alarm, distress and contact calls given by fledglings and juveniles. The vocalisations of the White-winged Chough included both noisy (harsh), pure harmonic and tone vocalisations, while the vocalisations of the Little Raven showed less variation, with most vocalisations having a combined noisy and harmonic structure. In both species, begging calls were very similar in structure to other vocalisations produced in later stages of development, suggesting that the production of begging vocalisations may be important in the development of adult vocalisations.