Red-billed Leiothrix sexing is a matter of colour

Capsule The Red-billed Leiothrix (Leiothrix lutea) is a superficially sexually monochromatic colourful bird native to the Indian subcontinent, which has colonized many locations across the world as an introduced species. We investigated the best method to accurately sex the species, capturing and measuring the colour and external morphometry of a sample of 57 individuals, which were later sexed molecularly from blood samples. We found that sexes showed no dimorphism in biometry or size of wing coloured-patches. However, a Discriminant Function based on hue of the throat, chroma of the crown and lightness of the breast allowed us to determine sex with an accuracy of 91%.