Detection and Molecular Characterization of a Novel Species of Circovirus in a Tawny Owl (Strix aluco) in Southern Italy

Thanks to recent developments in molecular methods, many new species have been discovered within the genus Circovirus, which comprises viruses of veterinary relevance found in a broad range of hosts. In particular, several circoviruses are known to infect birds, often causing immunosuppression and feathering disorders. Nonetheless, nothing is known about their circulation in birds of prey. In this study, samples from 61 birds of prey representing ten different species, recovered by a wildlife rescue centre in Southern Italy, were taken at necropsy and analysed by PCR with pan-Circovirus primers. Only one sample, collected from a tawny owl (Strix aluco), tested positive. Its genome, sequenced by primer walking, displays the typical features of circoviruses. Based on demarcation criteria, the detected strain qualifies as a novel species, which was named “tawny owl-associated circovirus” (ToCV). Phylogenetically, ToCV clustered with mammalian rather than avian circoviruses, and its closeness to a rodent circovirus suggests that its host may have been a micromammal eaten by the tawny owl. On the other hand, its detection in the spleen fits with the tropism of other avian circoviruses. Little can be therefore said on its biology and pathogenicity, and further efforts are needed to better characterize its epidemiology.

Raptor wing morphing with flight speed

In gliding flight, birds morph their wings and tails to control their flight trajectory and speed. Using high-resolution videogrammetry, we reconstructed accurate and detailed three-dimensional geometries of gliding flights for three raptors (barn owl, Tyto alba ; tawny owl, Strix aluco , and goshawk, Accipiter gentilis ). Wing shapes were highly repeatable and shoulder actuation was a key component of reconfiguring the overall planform and controlling angle of attack. The three birds shared common spanwise patterns of wing twist, an inverse relationship between twist and peak camber, and held their wings depressed below their shoulder in an anhedral configuration. With increased speed, all three birds tended to reduce camber throughout the wing, and their wings bent in a saddle-shape pattern. A number of morphing features suggest that the coordinated movements of the wing and tail support efficient flight, and that the tail may act to modulate wing camber through indirect aeroelastic control.

Small mammals of the suburban areas of Warsaw in the diet of the tawny owl Strix aluco

We investigated the composition of small mammals at nine locations in the southwestern suburban zone of Warsaw (central Poland) through the analysis of the pellets of the Tawny owl Strix aluco. In total, we recorded 611 individuals of 15 species of small mammal communities in the diet. Rodents constituted the most numerous mammalian order. Among the most abundant prey we recorded were Myodes glareolus (63 individuals = 10.3% of all mammals), Apodemus agrarius (56 individuals = 9.2%) (173), Apodemus flavicollis (54 individuals = 8.8%), Mus musculus (48 individuals = 7.9%) and Microtus arvalis (44 individuals = 7.2%). We recorded also some species rarely captured by the tawny owl: Nyctalus noctula and Mustela nivalis. Species composition of small mammals of the study area resembled city parks, with several species typical for anthropogenic landscape.