My dissertation work focuses on avian malaria; a nearly ubiquitous zoonotic disease caused by parasites that are vectored by biting flies, mosquitoes, and midges. I study infections with these parasites in two closely related songbird species– the Black-capped and Mountain Chickadee. These songbirds are so closely related that they occasionally will hybridize and produce fertile offspring and I have found them to be infected with both shared and unique avian malaria lineages. Interestingly, because both of these songbird species are non-migratory passerines that typically disperse only once in the juvenile stage of their lives, we know that their malaria parasite infections are likely representative of surrounding ecology and vector communities. My field sites span an elevation gain of 5,000ft and I have found patterns of malaria parasite community turnover along this elevation gradient. Combined, these factors make chickadees an excellent study system for addressing my questions aimed at improving our understanding of how host-specificity and elevation shape avian malaria diversity.