Meeting Abstract
The volatile compounds in preen oil, a secretion of the avian uropygial gland, contributes to bird odor. The composition of these compounds has been shown to vary by species, population, individual, sex, and season. But what information does the odor blend contain? Using the dark-eyed junco as a model, we asked whether preen oil composition varies based on the presence and intensity of infection with avian malaria parasites. Haemosporidians are vector-transmitted blood parasites that cause malaria in vertebrate hosts. Mosquitoes that vector these parasites are known to prefer hosts with haemosporidian infections, but the mechanism behind this preference is unclear. If vectors use host odor to find preferred hosts, we predict that preen oil volatile composition of infected birds will vary from those of uninfected birds. In addition, if parasite growth induces a shift in host volatile composition, we predict that one or more volatile compounds should correlate in proportion with parasite load. To test these predictions, we collected preen oil and blood samples from non-migratory juncos in the Appalachian Mountains of Virginia during the early breeding season. We used gas chromatography-mass spectrometry to quantify the relative proportions of 15 volatile compounds in each bird’s preen oil composition. Next, we analyzed DNA from blood samples through nested PCR and qPCR to identify haemosporidian infections and assess parasite loads. We will discuss differences in odor blend between infected and uninfected birds of both sexes, and the potential ecological relevance of these differences.
