Higher prevalence and diversity of avian haemosporidian infections in an elevation generalist compared to an elevation specialist

Avian haemosporidians are cosmopolitan protozoan parasites that infect a wide range of bird species and can cause the disease avian malaria. Previous studies that have examined haemosporidian patterns of infection have predominantly been focused on hosts that are either tropical or long-distance migrants. We sought to explore how the elevation range of avian hosts influences the prevalence, probability of infection, diversity, and community turnover of their haemosporidian infections, in a Nearctic host study system uncoupled from long-distance migration. We sampled two North American songbirds for haemosporidians, the mountain chickadee (Poecile gambeli) which breeds across a wide elevation span, and the brown-capped rosy finch (Leucosticte australis), which breeds exclusively at high elevations above tree line. We tested whether elevation along a single transect would play a stronger role in shaping the diversity of avian haemosporidian infections compared to geographic distance between sampling sites, but at more discrete elevations. Our results indicate that the elevation generalist sampled across a single transect was infected with a higher diversity of haemosporidian haplotypes and at a higher infection prevalence, than the elevation specialist sampled across six mountain ranges. These findings are consistent with similar studies that have examined geographic patterns of haemosporidian infections in hosts that are long-distance migrants, that are sampled during their breeding season.