The function of colourful plumage and song in female lovely fairy-wrens
A project undertaken at the Department of Zoology, The University of Melbourne, and supervised by Raoul Mulder
Darwin’s (1871) theory of sexual selection was inspired by his observations of the remarkable sexual dimorphism apparent in nature. Since then, the elaboration of ornamental traits like complex song and conspicuous plumage has been almost universally attributed to sexual selection. However, recent work on bird song has challenged this view with evidence that song is common among female songbirds, and was present in the ancestor of modern songbirds (Odom et al 2014). What selective forces drive the evolution of elaborate female ornaments is a topic of immense current interest and controversy (Clutton-Brock 2007). The traditional view that female ornamentation is a non-adaptive by-product of selection on male ornaments has been challenged by suggestions that female ornamentation could also evolve as a result of sexual selection, or through broader processes such as social selection (Tobias, Montgomerie & Lyon 2012). However, no study has yet investigated the function of elaborate song and plumage in females and males simultaneously to test hypotheses for trait elaboration in one system. A general understanding of the evolution of elaborate traits – in both sexes, not just one, and in a diversity of social contexts, not just mating systems – requires that we significantly broaden our scope of investigation and consider a range of hypotheses.
This project will use the lovely fairy-wren (Malurus amabilis) to test three key hypotheses for the evolution of elaborate ornamental traits such as complex song and colourful plumage in females:
Outcomes to Date
We monitored more than 50 groups of 118 individuals in lowland forest, saltmarsh and mangroves in Cairns the region, QLD over the duration of the project. Territories ranged in size from 0.8 to 4.6 ha, and birds were found at a density of 0.92 birds per hectare. Our study shed light on the ecology and breeding behaviour of this previously unstudied species, as well as the role of song and plumage ornaments.Lovely fairy-wren ecology and breeding behaviour
Chenoweth SF, Doughty P & Kokko H (2006). Can non-directional male mating preferences facilitate honest female ornamentation? Ecology Letters, 9: 179-184.
Clutton-Brock T (2007). Sexual selection in males and females. Science, 318: 1882-1885.
Darwin C (1871). The descent of man, and selection in relation to sex. London: John Murray.
Odom KJ, Hall ML, Riebel K, Omland KE & Langmore NE (2014). Female song is widespread and ancestral in songbirds. Nature Communications 5: 3379, doi: 10.1038/ncomms4379
Tobias JA, Montgomerie R & Lyon BE (2012). The evolution of female ornaments and weaponry: social selection, sexual selection and ecological competition. Philosophical Transactions of the Royal Society B-Biological Sciences, 367: 2274-2293
Leitão, A.V., Hall, M.L., Venables, B & Mulder, R.A, (2018): Ecology and breeding biology of a tropical bird, the Lovely Fairy-Wren (Malurus amabilis), Emu-Austral Ornithology, DOI: 10.1080/01584197.2018.1498745