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

The prevalence of Plasmodium, Haemoproteus, and Leucocytozoon haemosporidian infections was investigated at three stations of the Khingan Nature Reserve, Amur oblast, 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): Plasmodium and Leucocytozoon parasites were significantly more common at the Karapcha station, while Haemoproteus 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) Haemoproteus at Kleshenskii. Long-distance migrants had a higher prevalence of Plasmodium than resident bird species at both Kleshenskii and Karapcha. We assume that Plasmodium parasites are also actively transmitted on the wintering grounds. At the Lebedinii station, the frequency of Leucocytozoon 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 the Lebedinii station. 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.