Carotenoid-based plumage coloration reflects hemoparasite infection and local survival in breeding great tits.

Carotenoid-based sexual coloration has been hypothesised to be prevalent across many vertebrate taxa because it reliably reflects individual phenotypic quality in terms of foraging efficiency or health status due to the trade-off between signal colour and use of carotenoids for immune function and detoxification. We investigated the ventral, yellow coloration of breeding adult great tits (Parus major L.) in relation to sex, age, breeding habitat, local survival and infection status with respect to Haemoproteus blood parasites. The extent of plumage coloration (estimated as hue and lutein absorbance) was generally higher in rural than in urban birds. Males had higher values of hue than females. In both male and female yearlings, the plumage of unparasitised individuals had a greater hue of yellow than parasitised ones, while older males revealed the opposite pattern. The survival of infected yearlings was worse than that of uninfected yearlings, while the opposite was true for old breeders. Survivors had generally higher values of hue than non-survivors. These results are consistent with predictions of functional hypotheses, suggesting that carotenoid-based plumage coloration serves as a signal reflecting individual quality in terms of health status and local survival.