Haemosporidian infection prevalence varies temporally and spatially and Leucocytozoon infections are male biased in Song Sparrows

Abstract

Abstract Haemosporidian parasites are significant global drivers of avian disease and infections are affected by complex ecological and biological interactions. We quantified variation in haemosporidian infection prevalence of Plasmodium, Haemoproteus, and Leucocytozoon in 311 Song Sparrows (Melospiza melodia) from 2 breeding populations across years, seasons, age classes, and sexes, finding significant differences in infection prevalence across years, seasons, and sites, as well as sex differences in Leucocytozoon infection prevalence. We also found that birds were more likely to be infected with Plasmodium than Leucocytozoon and coinfections were more likely than expected. Many avian haemosporidian studies use data collected over a short period of time at one location, and few studies investigate multi-year infection dynamics across populations. However, such long-term studies are important because ecological factors can affect the distribution and prevalence of vector-borne pathogens like malaria. Because biological factors can also affect the likelihood of exposure to vector-borne pathogens, it is also important to determine how host traits influence infection dynamics. Our results demonstrate that the prevalence and composition of avian haemosporidian infections can be highly variable, making sampling regimes a key consideration when drawing conclusions from study results. To better understand the fitness consequences of haemosporidian infection in avian hosts, future work should take ecological and biological variation into account when evaluating the effects of infection on aspects of condition and quality, reproductive success, and survival.