ИСТИНА

The prevalence of blood parasites in tropical birds of the Old World has been significantly less studied compared to birds from other regions. In this study, we investigated the prevalence of Haemoproteus spp. in various taxonomic and ecological avian groups in Cát Tiên National Park (southern Vietnam) during the dry season (March to May) over six years. To assess Haemoproteus spp. parasitemia, we counted the number of infected erythrocytes per 10,000 erythrocytes, analyzing about 700 blood smears from 102 species of free-living tropical birds. In addition to blood parasites, we also estimated the presence of some ectoparasites (Ischnocera and Amblycera chewing lice, Hippoboscidae louse flies, and feather mites), leukocyte profile parameters (including total leukocyte count and H:L ratio), and basal metabolic rate (BMR) in these birds. We found Haemoproteus spp. in 19.6% of the smears. For statistical analysis, we used binary logistic regressions, negative binomial GLM and zero-inflated negative binomial GLM. Suboscine passerines had significantly lower rates of Haemoproteus spp. parasitemia compared to oscines and non-passerines. Among passerines, the average predicted level of Haemoproteus spp. parasitemia was seven times higher in migratory species than in sedentary ones. In the model accounting for three main taxonomic groups (oscines, suboscines, and non-passerines), the Haemoproteus spp. intensity of invasion was positively related to mass-independent BMR. The likelihood of an individual being infected with Haemoproteus spp. increased with body mass and the total leukocyte count. Among tropical residents, this likelihood is significantly higher in oscines compared to suboscines and non-passerines.