Carotenoid supplementation positively affects the expression of a non-visual sexual signal.
Carotenoids are a class of pigments which are widely used by animals for the expression of yellow-to-red colour signals, such as Phone Accessories bill or plumage colour.Since they also have been shown to promote immunocompetence and to function as antioxidants, many studies have investigated a potential allocation trade-off with respect to caroten