An Analysis of the Dawn Vocalisation of a Male Grey Shrikethrush (Colluricincla harmonica)

Abstract

ABSTRACT The vocalisations of the Grey Shrikethrush are loud, clear, pleasing to the ear, and a stand-out feature of the bird song in areas in which they occur. However, data on these vocalisations in the literature are sparse, as are any attempts at either quantitative or qualitative analysis. Consequently, almost nothing is known about the character of this very obvious song. We made eight recordings of the dawn song of a male individual at the start of the breeding season on the south-east coast of Australia, in spotted gum forest, 350 km south of Sydney. The song comprised discreet groups of notes which we call syllables. The syllables are sung about every 5-10 seconds, and the individual produced 20 different syllables over the course of the eight recordings. Various analyses revealed that new syllables were added gradually over the recording period, and reached a maximum number at the sixth recording, nine days after the first recording. The frequency of use of particular syllables varied markedly, it was common for some syllables to be used as repeats, particular heterogeneous syllable couplets were commonly used as alternations, and the sequence of syllables could be remarkably similar between different recordings. We suggest a way forward to determine whether these patterns are a common feature of the vocalisations of this species.