Helminth parasites of northern spotted owls (Strix occidentalis caurina) from Oregon

Endohelminths in Bird Hosts from Northern California and an Analysis of the Role of Life History Traits on Parasite Richness

The life history characteristics of hosts often influence patterns of parasite infection either by affecting the likelihood of parasite exposure or the probability of infection after exposure. In birds, migratory behavior has been suggested to affect both the composition and abundance of parasites within a host, although whether migratory birds have more or fewer parasites is unclear. To help address these knowledge gaps, we collaborated with airports, animal rescue/rehabilitation centers, and hunter check stations in the San Francisco Bay Area of California to collect 57 raptors, egrets, herons, ducks, and other waterfowl for parasitological analysis. After dissections of the gastrointestinal tract of each host, we identified 64 taxa of parasites: 5 acanthocephalans, 24 nematodes, 8 cestodes, and 27 trematodes. We then used a generalized linear mixed model to determine how life history traits influenced parasite richness among bird hosts, while controlling for host phylogeny. Parasite richness was greater in birds that were migratory with larger clutch sizes and lower in birds that were herbivorous. The effects of clutch size and diet are consistent with previous studies and have been linked to immune function and parasite exposure, respectively, whereas the effect of migration supports the hypothesis of "migratory exposure" rather than that of "migratory escape."

Parasitic helminths in the digestive tract of six species of owls (Strigiformes) in Spain

A survey was carried out in Catalonia, Spain to determine the prevalence of parasitic helminths infesting the digestive tract of nocturnal raptors (Strigiformes). One hundred birds belonging to six owl species were examined. The number of birds examined ranged between three and 30. The overall level of infestation was 65% and the most frequent helminths present were nematodes, followed by trematodes, cestodes and acanthocephalans. Strigiformes showing the highest levels of infestation were little owls (Athene noctua), 86.7% of which were infested. Helminths with the highest prevalence were Synhimantus spp., intestinal capillarids, Brachylaima spp., cestodes and Centrorhynchus aluconis.

Helminth fauna of Falconiform and Strigiform birds of prey in Galicia, Northwest Spain

This is a survey of the helminth fauna of 285 individuals of 14 species of birds of prey (Falconiformes and Strigiformes) from Galicia (northwest Spain), namely Buteo buteo, Accipiter nisus, A. gentilis, Milvus migrans, M. milvus, Pernis apivorus, Circus pygargus, Falco tinnunculus, F. peregrinus, F. subbuteo, Tyto alba, Strix aluco, Asio otus and Athene noctua. A total of 15 helminth species were detected, namely 8 nematodes ( Eucoleus dispar, Capillaria tenuissima, Synhimantus laticeps, Microtetrameres sp., Physaloptera alata, Procyrnea leptoptera, Hovorkonema variegatum and Porrocaecum angusticolle), 4 cestodes ( Cladotaenia globifera, Paruterina candelabraria and Mesocestoides sp.), 2 trematodes ( Neodiplostomum attenuatum and Strigea falconis), and 1 acanthocephalan ( Centrorhynchus globocaudatus). The helminth communities observed were basically similar, although there were marked differences in species richness, which was higher in falconiforms (except for A. gentilis) than in strigiforms. More specifically, species richness was highest in B. buteo (13 species), followed by A. nisus (11 species). In the falconiforms, the helminth species present generally exhibited a clear relationship with host diet. In the strigiforms, by contrast, species richness was lower than expected given the host's diet, suggesting that a different explanation is needed.