Growth conditions affect carotenoid-based plumage coloration of great tit nestlings

Carotenoid-based integument colour in animals has been hypothesised to sign al individual phenotypic quality because it reliably reflects either foragi ng efficiency or health status. We investigated whether carotenoid-derived yellow plumage coloration of fledgling great tits (Parus major) reflects th eir nestling history. Great tit fledglings reared in a poor year (1998) or in the urban habitat were less yellow than these reared in a good year (199 9) or in the forest. The origin of nestlings also affected their coloration since nestlings from a city population did not improve their coloration wh en transferred to the forest. Brood size manipulation affected fledgling co lour, but only in the rural population, where nestlings from reduced broods developed more yellow coloration than nestlings from increased and control broods. Effect of brood size manipulation on fledgling plumage colour was independent of the body mass, indicating that growth environment affects fl edgling body mass and plumage colour by different pathways.