Epizootiology of blood parasite infections in passerine birds from central New Jersey

Abstract

One or more genera of hematozoa were found in blood smears of 204 (29.3%) of 697 birds representing 59 species. Parasites included Leucocytozoon spp. (16.6% prevalence), Haemoproteus spp. (9.9%), Plasmodium spp. (3.0%), Trypanosoma spp. (4.2%), and microfilariae of filariid nematodes (1.0%). Of 353 birds (48 species) tested for trypanosomiasis by blood culture, 141 (39.9%) were found to be positive. Several new host–parasite associations were identified. Prevalences were lowest in the summer and highest in the spring. During the summer, hatching-year birds were found to be infected less frequently than were older birds. Ground-feeding birds were infected with Leucocytozoon spp. at a significantly higher rate than were birds that characteristically feed above ground. Although the vertical stratum preferred for foraging was significantly associated with that of nesting, no significant association between preferred nesting stratum and prevalence of Leucocytozoon spp. infection among locally breeding birds was found. The results of this study, when compared with those of others, indicate that the epizootiology of avian hematozoan infections may vary greatly according to the locality studied. An examination of the effects of blood sampling (whether by nail clipping or jugular venipuncture) on the birds revealed no significantly adverse effect of sampling on bird survival.