Vibrant blue plumage of breeding male fairy-wren may be linked to their higher visual sensitivity to ultraviolet (UV) light.

Researchers found that different species of fairy-wren can have either violet or UV-type vision. Species with UV-type vision have greater sensitivity to UV/blue light and have blue mating plumage.

The UV vision makes the blue male plumage stand out more from their environment and is therefore more attractive to potential mates.