Author: Christine Evans
Evans, Christine, 2016 Female song in the superb fairy-wren (Malurus cyaneus): perspectives informed by function and ontogeny, Flinders University, School of Biological Sciences
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Songbirds (oscine passerines), the largest Order of birds, have intrigued humans for centuries given their capacity to learn complex vocalisations and produce complex songs. Despite the fact that female songbirds also sing, the vast majority of research into song learning, as well as the functions of song, has come from studies on male birds. My thesis asks and answers some fundamental questions about whether there are differences in song learning in sons and daughters when both parents produce complex solo song, and if there are gender-specific differences in the costs of adult song. I use a model Australian songbird system with male and female song, the superb fairy-wren (Malurus cyaneus). Using observational and experimental cross-fostering approaches, my thesis shows that male and female fledglings produced songs of comparable complexity and sang song element types of (foster) social mothers and fathers. I conclude that both adult males and females were vocal tutors for young birds. Given that offspring learned the vocal elements of both parents, I tested if the male-centric hypothesis for mate choice by females explains pairing patterns whereby females with complex song should be paired with males with complex song. While this was rejected I instead found assortative pairing for element type (not complexity) whereby females with complex song were paired with males with many shared element types. Finally, there were gender differences in the costs of singing. Females that produced many chatter songs inside the nest had higher nest predation compared with males with high song rate close to the nest. Therefore, this thesis identifies singing as costly for females, but also shows that female singing behaviour plays a role to vocally tutor fledged young. I suggest that females may increase their fitness by selecting males with a shared vocal repertoire, to enhance the efficacy of territory defence. The outcomes of the thesis raise new theoretical frameworks for sexual selection linked with shared territory defence (commonly referred to as social selection), as well as new ideas to test the function of female song for ontogenetic patterns when both sexes sing as adults and both sexes learn song during development.
Keywords: female song, malurus, superb fairy-wren, song learning, vocal tutoring
Subject: Biological Sciences thesis
Thesis type: Doctor of Philosophy
Completed: 2016
School: School of Biological Sciences
Supervisor: Professor Sonia Kleindorfer