Recently, we've started investigating the evolutionarily mechanisms maintaining the diverse colouration and head polychromatism in the Gouldian finch (Erythrura gouldiae).

 

Polychromatism, the occurrence of two or more discretely coloured morphs within a population or species, represents a rare but particularly puzzling form of colour signalling. Gouldian finches possess a genetically determined polychromatism with three distinct head morphs (black, red and yellow).

 

The head colour polymorphism of Gouldian finches is determined by two genes (one sex-linked and one autosomal), which stimulate or suppress the production of plumage pigments (melanin, canthaxanthin and lutein).

 

Uniquely, the morphs naturally co-occur within small populations at different frequencies; black headed morphs are the most common (±70%), red-headed moderately common (±30%) and yellow headed extremely rare (±0.02-0.03%).

Our work aims to use a combination of experimental studies on captive birds, genetic sampling, as well as field work on wild populations to examine a number of currently highly debated issues in evolutionary biology, involving colour signalling, stable polymorphisms and the neglected interaction of sexual selection and population processes in small populations.

The Gouldian finch is a grassland finch (family Ploceidae) endemic to savannah woodlands in tropical northern Australia. Although once common throughout the tropical savannas, in the last 20-30 years their numbers have declined drastically, predominantly because of land management alterations. As a consequence, Gouldian finches are now one of Australia's most endangered passerines with less than 2500 estimated to remain in small, fragmented populations in the wild.

 

The field work for this project will be undertaken on one of the largest wild populations (± 400 birds), which is situated at the Australian Wildlife Conservancy's (AWC) Mornington Sanctuary (located in the Central Kimberley, Western Australia). This project will be run in collaboration with the large scale land management and Gouldian finch conservation programme recently implemented at the station.