Extra-group Courtship Displays and Other Reproductive Tactics of Superb Fairy-wrens

Abstract

A behavioural study was conducted to investigate reproductive strategies of female and male superb fairy-wrens (Malurus cyaneus). Such strategies are of particular interest in this species because males and females form lifelong pair bonds, yet exhibit the highest documented frequency of extra-pair mating among birds. In this study, a conspicuous element of behaviour of males was the performance of a courtship display involving the presentation of a flower or flower petal. This unusual display was performed exclusively (97%) for extra-group females during excursions into neighbouring territories by lone males, and appears to have evolved specifically for the purpose of soliciting future extra-pair fertilisations. Since displays were never followed by an immediate copulation, the behaviour appears most consistent with self-advertisement by males. Females appear to control copulation, and may assess males through their displays. Copulations were rarely seen in this study, and the proportion of all observed copulations that were extra pair (11%, N = 1) significantly underestimated the frequency of extra-pair fertilisation (76%) determined from previous DNA fingerprinting studies. When and where copulations occur remains poorly known. Consistent with control of copulation by females, males showed evidence of only weak mate guarding, and may follow females primarily for copulation access. The evolution of a unique and context-specific extra-group solicitation display emphasises the significance of extra-pair fertilisations in the mating system of this species.