Repertoire size, song sharing and type matching in the Rufous Bristlebird (Dasyornis broadbenti)

Abstract

A strong pattern has emerged between sedentary behaviour and song sharing between territorial neighbours for avian species that possess song repertoires. This paper investigates song-repertoire size, and rates of song sharing and type matching, in the Rufous Bristlebird (Dasyornis broadbenti), a southern Australian species for which there is strong evidence for sedentary and territorial behaviour. For 12 focal individuals (6 male, 6 female), estimated mean repertoire size was 31 song types for male birds, and 14 song types for females, recorded at the start of the breeding season. While the female song was similar in structure to the final phase of the male song, there was no sharing of song types between the sexes. A high degree of song sharing was exhibited in both sexes, with males sharing an average of 65% of song types, and females sharing 59% of song types, with immediate territorial neighbours. These rates of song sharing between neighbours were significantly greater than rates of song sharing between non-neighbouring individuals, although common song types between non-neighbours were encountered. Furthermore, bristlebirds used these common song types significantly more often than song types that were unique to their repertoires. While male neighbours preferentially matched song types, there was no evidence for repertoire matching. The degree of song sharing in neighbouring Rufous Bristlebirds is therefore consistent with the observed relationship between sedentary behaviour and high levels of song sharing.