Geographic song variation within and between populations and subspecies of the rufous bristlebird, Dasyornis broadbenti

Abstract

This work investigated whether the songs of the rufous bristlebird, Dasyornis broadbenti, vary between populations that have become isolated through habitat clearance, in a similar way to that found between island populations of other bird species, separated by ocean. In addition, the extent of song variation between the two extant subspecies of D. broadbenti was investigated. The nature of song elements did not differ between isolated sites within each subspecies' distribution more than between sites sampled within continuous populations. However, multivariate analyses of spectral and temporal features suggested that these features differed between isolated populations more than within continuous populations. In addition, both the nature of song elements and spectral and temporal features differed significantly between the two extant subspecies of D. broadbenti. These taxonomic analyses of song thus supported recent revisions of the subspecific boundaries of D. broadbenti. While there was some evidence that temporal and spectral song features varied more between isolated populations than within a continuous population, it was difficult to eliminate the effect of distance on song variation. Although evidence for song variation as a result of isolation was not strong for this species, clearance of the habitat utilised by D. broadbenti is relatively recent. The suggestion that communication systems of animal populations can be disrupted following isolation through habitat clearance is one that warrants further investigation, especially in taxa with older histories of fragmentation. This study also highlighted the potential for using behavioural information to assist with taxonomic investigations.