Carotenoid-based breast plumage colour, body condition and clutch size in red fodies (Foudia madagascariensis)

Carotenoid-based feather colouration is a classic example of a condition-dependent ornamental trait. In some species of birds, red, orange and yellow feather colouration reflects male quality and advertises the carotenoid concentration of feathers. Such colouration is an important aspect of mate selection by females. The red fody (Foudia madagascariensis) is a highly sexually dimorphic species of the family Ploceidae, in which males exhibit extensive carotenoid-based plumage. We investigated associations between body condition, clutch size, first egg date and carotenoid-based red plumage colour of male red fodies. Breast plumage brightness was positively associated with male body condition, suggesting that this component of colour is condition-dependent. Brighter-red males did not breed earlier but were mated to females that laid larger clutches compared to females mated to duller-coloured males. These data suggest that red colour in red fodies has the potential to function as an honest signal of male quality.