The function of vocalisations and aggressive behaviour used by male Rufous Whistlers, Pachycephala rufiventris

Abstract

The function of vocalisations and aggressive behaviours observed in a free-living population of Rufous Whistlers, Pachycephala rufiventris, was studied throughout a breeding season in central western New South Wales. Individuals of the population were colour banded and the behaviour of adult males observed and quantified for 10-min periods during discrete stages of the breeding cycle. The population was found to be totally migratory or nomadic at this site; adult males participated in all breeding activities except nest construction. Two new courtship displays are described and six distinct call types were identified and recorded. Total call rates reached a peak during nest construction, before gradually falling to very low rates by the cessation of breeding activities. On the basis of extensive field observations it was concluded that this species uses calls for both territorial definition and intersexual attraction. While some calls were more frequently associated with a territorial or intersexual function, none of the six calls was used exclusively for either. Aggressive behaviour was quantified and was most prevalent early in the breeding season when territories and pair bonds were being established. Mate-guarding, in the form of periods that males spent within 5 m of the female, was most common during nest construction when females were fertile.