Prevalence of Haemosporidian Infection in Resident and Migratory Bird Species in the Khingan Nature Reserve, Amur Region

The prevalence of , , and haemosporidian infections was investigated at three stations of the Khingan Nature Reserve, Amur Region, Russian Far East. Between 2021 and 2024, we sampled mainly passerine birds, with a total of 751 individuals belonging to 68 species. Birds were mist-netted during the breeding season at the "Kleshenskii" and "Karapcha" stations, and during the spring and autumn migrations at the "Lebedinii" station. The prevalence of different haemosporidian genera varied between "Karapcha" (coniferous–deciduous forest) and "Kleshenskii" (swampy plain with forest patches): and parasites were significantly more common at the "Karapcha" station, while parasites dominated at the "Kleshenskii" station. Based on these data and on infection patterns in resident bird species, we hypothesize that haemosporidians from all three genera can be transmitted at "Karapcha", but only (or mainly) at "Kleshenskii". Long-distance migrants had a higher prevalence of than sedentary bird species at both "Kleshenskii" and "Karapcha". We assume that parasites are also actively transmitted on the wintering grounds. At the "Lebedinii" station, the frequency of infections was higher in autumn than in spring. This pattern could be related to parasite transmission in the northern latitudes where the birds migrating through "Lebedinii" breed. In general, birds can become infected by haemosporidians either (1) on the breeding grounds or (2) on the wintering grounds and during migration. Our study revealed that, among breeding birds, location (i.e. "Kleshenskii" vs. "Karapcha") most strongly affected the infection prevalence, whereas among migrants at "Lebedinii", season (spring vs autumn) was the key factor. Whether a species was resident or migratory rendered a much smaller effect. We thus conclude that, in our study area, the prevalence of haemosporidian infection depended more on breeding-ground conditions than on those at the wintering grounds.