Variation in avian haemosporidian infection patterns in Daurian Redstarts (Phoenicurus auroreus) across eastern China

Avian haemosporidian parasites are widespread vector-borne pathogens that can influence host fitness, survival, and population dynamics. However, infection patterns and parasite lineage diversity remain poorly documented in many Asian bird populations, particularly within single host species sampled across contrasting geographic contexts. Here, we investigated haemosporidian infections in the Daurian Redstart ( Phoenicurus auroreus ), a widespread passerine in eastern China. Between 2022 and 2025, we sampled 508 individuals at four locations during breeding and non-breeding periods and screened for infections using nested PCR and mitochondrial cytochrome b sequencing. Overall infection prevalence was 30.31%, with Plasmodium as the dominant genus, followed by Leucocytozoon and Haemoproteus . We identified 44 parasite lineages, including 19 novel lineages, indicating substantial hidden diversity in this host species and region. Infection prevalence and parasite lineage composition differed significantly among locations, whereas no significant effects of host sex were detected. These results reveal substantial variation in haemosporidian infections among geographically and temporally distinct sampling contexts within a single host species, suggesting that local ecological and transmission conditions may contribute to host–parasite dynamics. Our study highlights the value of single-host, lineage-level surveys for uncovering hidden parasite diversity and documenting haemosporidian variation in understudied regions of Asia.