The singing behaviour of the Noisy Scrub-bird, Atrichornis clamosus: congeneric comparisons and the feasibility of using individual variation in song as a census tool

Abstract

The Noisy Scrub-bird, Atrichornis clamosus, is a small, elusive, threatened passerine endemic to south-western Australia. Its elusive nature limits the usefulness of conventional individual marking methods, hampering efforts to study the biology of this species. The territorial songs of 12 territory-holding male A. clamosus were recorded at Two Peoples Bay Nature Reserve in order to compare the singing behaviour of this species with that of the Rufous Scrub-bird, A. rufescens, and to investigate the feasibility of using this vocalisation as a method of identifying individual male A. clamosus in the field. In contrast to that of A. rufescens, the territorial song of A. clamosus is structurally complex and highly variable. Each territory-holding male A. clamosus has a repertoire of 4–7 song types, which is sung with a pattern of immediate variety rather than eventual variety, as in A. rufescens. The song types comprising the repertoire of an individual A. clamosus are not necessarily unique to that individual and may be shared with one or more other males. In some cases the repertoires of several birds may consist of the same song types. Such extensive song sharing precludes unambiguous individual identification. Therefore, the territorial song of A. clamosus is an unsuitable method of individual identification.