Living with Malaria: Testing the relationships between plumage characteristics and associated carotenoid concentrations in a species of woodpecker

Avian malaria is a vector-borne disease whose effects on reproductive success and life history strategies are poorly understood. Avian malaria likely has consequences on carotenoid metabolism and color display in many species of birds. Carotenoid deposition in feathers and the associated yellow, orange, and red feather colorations are often used to evaluate individual quality. We analyzed feathers and tissues from specimens of a woodpecker species, Sphyrapicus ruber, collected from California and Oregon in 2012. This species is known to contract avian malaria and has several carotenoid-based plumage patches on its body. Infected individuals had a higher percentage of red, carotenoid-based plumage on the breast region but a lower concentration of carotenoids deposited in feathers, compared to individuals not infected with avian malaria. We suggest that avian malaria influences carotenoid metabolism and that the type of carotenoid being deposited in feathers is more important, biologically, than overall carotenoid concentrations. With the vectors of avian malaria experiencing range changes, our work helps shed light on how avian malaria may affect avian life strategies.