Diversity and function of vocalisations in the cooperatively breeding Chestnut-crowned Babbler

Samenvatting

Vocalisations represent the primary mode of communication for most birds and vary greatly in form and function within and between species. Cataloguing the vocal repertoire of a species is a key foundation for behavioural research, as it provides both an objective measure of vocal complexity and a basis for further studies of vocal function. Here we present a descriptive catalogue of the vocal repertoire of the Chestnut-crowned Babbler (Pomatostomus ruficeps), a cooperatively breeding passerine endemic to inland south-eastern Australia. Using behavioural observations and simple methods of acoustic classification we identify and suggest functions for 13 main types of vocalisations, and also report five less common vocalisations that could not be assigned a unique function. Babblers possess no song, in the sense of a vocalisation primarily used for inter-group or territorial communication. The 13 calls with clear functions can be broadly classified into three alarm calls, five contact calls, and four social-interaction calls, with a final call used in both social and alarm contexts. This study represents the first catalogue of vocal repertoire in pomatostomid babblers, and aims to contribute to future comparative analyses of vocal complexity and inspire further work on the relationship between call structure and function.