Between- and within-population drivers of haemosporidian prevalence and diversity in American robins (Turdus migratorius)

Avian haemosporidians are a diverse group of parasites that infect birds
worldwide and have been a major focus of research for decades. Yet, few
studies have identified the drivers of infection at the intraspecific host
level. We aimed to study the drivers of prevalence and diversity of
haemosporidian parasites infecting a common North American songbird
species, the American Robin (Turdus migratorius), which breeds across most
of the continent. We found little seasonal variation in haemosporidian
prevalence in robins, although we detected a significantly positive
relationship between robin breeding latitude and co-infection with
different haemosporidian parasite lineages. Additionally, robins infected
with Plasmodium had a substantially better body condition than those of
uninfected robins, which could be due to migratory culling. We detected 31
haemosporidian lineages among the robins we sampled, of which eight were
novel. When matched against known haemosporidian lineages, our results
suggest that robins harbor a higher diversity of haemosporidian parasites
than previously known. The results of this study suggest that comparisons
of common, widespread bird species such as robins across their range could
help unveil novel aspects of the haemosporidian-host relationship and how
such a relationship may change under current and future rapid
environmental change.