Blood samples from birds of prey, 95 Strigiformes and 190 Falconiformes, were examined for the presence of haematozoan parasites. The birds had been admitted to a raptor recovery centre in Catalonia, north-east Spain. Parasites were counted in positive smears. A second blood sample was obtained from 99 birds at least seven days after their arrival at the centre. Haematozoa were detected in all seven species of Strigiformes and in nine of 19 species of Falconiformes. The overall prevalences in the two groups were significantly different, 30.5 per cent and 46.3 per cent in the noctumal and diumal raptors, respectively. Eleven species of haematozoan parasites were identified. The genus most commonly detected in members of the noctumal Strigiformes was Leucocytozoon , followed by Haemoproteus , Plasmodium and Trypanosoma . In the diumal Falconiformes only Leucocytozoon and Haemoproteus were detected. The highest infection rates were found in Accipiter nisus (sparrow hawks), Accipiter gentilis (goshawks) and Athene noctua (little owls). Relapses were detected in 9 per cent of the birds sampled twice. The highest intensity of infection (6.2 per cent) was observed in a Buteo buteo (buzzard) infected with Haemoproteus .

Prevalence of haematozoa in birds of prey in Catalonia, north-east Spain.

Except for a few studies in the eastern United States, little has been published on hemoparasites in owls. We surveyed the blood parasites of 108 Northern Saw-whet Owls (Aegolius acadicus) and 24 Flammulated Owls (Otus flammeolus) in Idaho during autumn migration in 1999 and 2000. We also surveyed 15 Flammulated Owls (FLOW) during breeding season in Utah from 2000. Leucocytozoon ziemanni, Haemoproteus syrnii, Haemoproteus noctuae, and Trypanosoma avium were identified. The overall prevalence of infection was 53% (78/147) and for the combined species, prevalences of Haemoproteus, Leucocytozoon, and Trypanosoma species were 20%, 39%, and 4%, respectively. Northern Saw-whet Owls (NSWO) had an overall prevalence of 51% (55/108), with prevalences of 6%, 47%, and 4% by hemoparasite genus, respectively. Flammulated Owls had an overall prevalence of 59% (23/39), with prevalences of 56%, 18%, and 5% by genus, respectively. This study provides baseline hematozoa information for two boreal owl species.

https://bioone.org/journals/journal-of-wildlife-diseases/volume-44/issue-2/0090-3558-44.2.475/Survey-of-Blood-Parasites-in-Two-Forest-Owls-Northern-Saw/10.7589/0090-3558-44.2.475.pdf

Survey of blood parasites in two forest owls, Northern Saw-whet Owls and Flammulated Owls, of western North America.

Understanding factors that determine haemosporidian prevalence is critical in predicting how parasite and avian host populations will respond to environmental change Here, we used molecular screening of blood samples from migrating northern saw‐whet owls Aegolius acadicus in eastern North America to characterize haemosporidian infections and examine parasite prevalence with respect to abundance of migrants, timing of migration, climatic conditions at the breeding grounds, and avian host age We identified three haemosporidian genera (Leucocytozoon, Plasmodium, and Haemoproteus) and discovered a new lineage of Leucocytozoon that is thus far specific to the northern saw‐whet owl We found no significant relationship between parasite prevalence and northern saw‐whet owl abundance or timing of migration After‐hatch‐year birds were significantly more likely to be parasitized by Leucocytozoon than hatch‐year birds, whereas prevalence of Plasmodium was higher in hatch‐year birds Of the three climatic variables analyzed at owl breeding grounds (temperature, precipitation, and snowpack days), lower average annual temperatures significantly increased the chance of a bird being parasitized by Leucocytozoon; no significant temperature‐dependent relationship was found for Plasmodium This study contributes to our general understanding of the relationship between parasite prevalence and host density, host age, resource abundance, and abiotic factors such as temperature and precipitation

Haemosporidian prevalence in northern saw‐whet owls Aegolius acadicus is predicted by host age and average annual temperature at breeding grounds

Blood parasites have been the subject of much research, with numerous reports of the presence of microfilariae in the peripheral blood (circulating microfilariae) of birds belonging to many orders. Current limitations in molecular characterization methods and species identification using morphological characters of circulating microfilariae are major obstacles to improving our understanding the biology of Filarioidea species, particularly in wildlife. The aim of this study was to partially fill these gaps, with particular emphasis on morphological features of microfilariae, which are the most readily accessible stages of these pathogens. Peripheral blood samples of 206 birds belonging to genera Acrocephalus (five species) and Sylvia (five species) were examined using the buffy coat method to process the blood samples for the presence of microfilariae. Positive birds were dissected to collect adult nematodes. Microfilariae and adult nematodes were described, and sequences of their mitochondrial cytochrome c oxidase subunit I and nuclear 28S rDNA gene fragments were obtained and used for molecular characterization and Bayesian phylogenetic inferences. Overall prevalence of microfilariae was 2.9%. Microfilariae were found in the blood samples from six birds (2 Acrocephalus scirpaceus and 1 each of A. arundinaceus, Sylvia atricapilla, S. borin and S. curruca), which were dissected. All parasite species observed were new. Eufilaria acrocephalusi sp. n. and Eufilaria sylviae sp. n. were present in subcutaneous, peritracheal and periesophageal connective tissues in A. scirpaceus and S. borin, respectively. Splendidofilaria bartletti sp. n. was found in finger joins of S. atricapilla. Illustrations of microfilariae and adult nematodes are shown, and morphological and phylogenetic analyses identified the DNA barcode haplotypes that are associated with these species. Phylogenetic analysis places the parasites of different genera in different closely related clades. Adult nematode morphological characters, which have been traditionally used in the taxonomy of Filarioidea species, have a phylogenetic value. Importantly, in our study parasites of different genera were readily distinguishable based on the morphology of their microfilariae. The link between molecular and morphology data requires more study in Filarioidea species research, particularly because this approach provides new knowledge on species identity using only readily accessible blood stages (microfilariae), thereby avoiding host dissection and thus minimizing harm to wildlife during research.

/pdf/molecular-and-morphological-characterization-of-three-new-3969gvjd8l.pdf

Molecular and morphological characterization of three new species of avian Onchocercidae (Nematoda) with emphasis on circulating microfilariae

We examined blood smears from 139 Northern Saw-whet Owls (Aegolius acadicus) to ascertain the prevalence of haematozoa in this species during fall migration in eastern North America. Owls were captured with mist nets on the Mohonk Preserve near New Paltz, New York from 1 October to 2 December 2011. We examined blood smears under an optical microscope at 200× and 1000× magnification, and observed four genera of haematozoa, Haemoproteus, Leucocytozoon, Plasmodium, and Trypanosoma, in addition to a genus or genera of microfilarial nematodes, unidentifiable by morphology. We found haematozoa in blood smears from both male and female Northern Saw-whet Owls and in both age groups sampled, i.e., hatching year and after hatching year. Leucocytozoon was the most common parasite, with an overall prevalence of 49.6%. Prevalence of Haemoproteus, microfilaria, Plasmodium, and Trypanosoma was 5.0%, 5.0%, 10.0%, and 2.9% respectively, and overall occurrence of infection was 64%. We found no difference in body c...

https://bioone.org/journals/The-Wilson-Journal-of-Ornithology/volume-126/issue-4/13-124.1/Prevalence-of-haematozoa-in-migrating-Northern-Saw-Whet-Owls-Aegolius/10.1676/13-124.1.pdf

S. J. Taft

Papers

Hematozoa of spring- and fall-migrating northern saw-whet owls (Aegolius acadicus) in Wisconsin