New study on Gouldian finches. Your colour, your size and your song are what matters if you are a bird choosing a mate. In a polymorphic species, where several colour variations exist side-by-side, mates are chosen often because they match the chooser.
Gouldian Finch - Of all the Australian grass the Gouldian Finch is the most striking. it lives in large flocks in the north of Australia on open grassy plains with scattered tall trees near sources of permanent water. Gouldian finches avoid human habitation. (ref: Reader's Digest Complete Book of Australian Birds).