Prevalence and local transmission of haemosporidian (Haemosporida) parasites in nestlings of birds of prey (Aves, Accipitriformes) in the temperate forests in Lithuania

Wild birds of prey (Accipitriformes) are infected with haemosporidian (Haemosporida) parasites worldwide, and it is known that these parasites can negatively affect their health. These birds are less studied due to their low densities in ecosystems, conservation status, and difficulty of accessing them in the wild. Therefore, in this study, we focused on nestlings of birds of prey that are accessible in their nests during late breeding stages in temperate forests in Lithuania. Investigating haemosporidian parasites in nestlings is crucial for understanding local parasite transmission. To identify the haemosporidian parasite species transmitted in Lithuania, we sampled nestlings of the white-tailed eagles (Haliaeetus albicilla), lesser spotted eagles (Clanga pomarina), and common buzzards (Buteo buteo) in 2019–2022. Blood samples were collected from the nestlings, and molecular methods were employed to sequence a fragment of the parasite's cytochrome b (cyt b) gene using specific primers (Plas1F/HaemNR3 and 3760F/HaemJR4). In addition to molecular techniques, microscopy was used to examine blood smears for the presence of parasites. Our results revealed that nestlings of birds of prey were infected only with Leucocytozoon spp., with an overall prevalence of 30.5%. The prevalence was similar between years, but it was significantly species-dependent. The common buzzard nestlings had the highest prevalence (80%), followed by the lesser spotted eagle (29.2%) and the white-tailed eagle (13.2%). A total of nine genetic lineages were identified, with five of them being novel. Our study demonstrates that Leucocytozoon parasites are actively transmitted to nestlings of birds of prey in Lithuania, with a high prevalence.