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.

Colonization of Urban Habitats: Tawny Owl Abundance Is Conditioned by Urbanization Structure

Natural habitats are being altered and destroyed worldwide due to urbanization, leading to a decrease in species abundance and richness. Nevertheless, some species, including tawny owls, have successfully colonized this novel habitat. Consequences at the population level have not been described; thus, our main objective was to describe the effects that urban structure have on the tawny owl population at local and landscape levels. Data were obtained from 527 survey points over 7 months in a large-scale owl survey in the Basque Country (northern Spain) in 2018. At the local scale, the interaction between forest and urban cover affected tawny owl abundance, the optimum being in medium forested areas. The interaction between urban cover and clumpiness index (urban patch distribution) showed a generally negative effect. At the landscape scale, its abundance decreased in complex-shaped urban patches and when distance between them was greater. In conclusion, at the local scale, when a minimal forest structure is present in urbanized areas, the species can exploit it. At the landscape scale, it prefers smaller urban towns to cities. Thinking ahead, the current tendency toward “green capitals” should benefit tawny owl populations.

Landscape Configuration Influences Species Occupancy Over Multiple Spatial Scales: A Case Study On Tawny Owl

ABSTRACT Landscape configuration can influence the distribution of species across multiple spatial scales. The primary factors related to this process are connectivity, the size and position of habitat patches, and edge effects. These factors together determine the overall fragmentation of a landscape, which in turn influences species occurrence. Although some species show a negative response to fragmentation, others benefit from it. Potential effects may act over multiple spatial scales, possibly with contrasting effects on species occurrence. We chose the Tawny Owl (Strix aluco), a ubiquitous and generalist species, to study the influence of fragmentation on species occurrence and to identify relevant landscape metrics, using multi-scale hierarchical modelling. Between 2016 and 2018, we recorded Tawny Owls on 64 sampling sites located in a forested landscape. We used a space-for-time substitution in the framework of occupancy modelling to assess Tawny Owl responses to landscape fragmentation. We found that the Tawny Owl is widespread in the study area. Its distribution across the landscape (larger spatial scale) was related to a heterogeneous configuration of forest patches, while high connectivity of coniferous forest influenced its occurrence at a smaller spatial scale (sites). Overall, the Tawny Owl prefers landscapes with well-connected forest patches and an uneven patch distribution in the surrounding area.

Identitas: Semantics-free and human-readable identifiers

In this article, we present a new approach to identifiers, one that aims to improve the management of ontologies. This approach overcomes some of the main flaws associated with the existing approaches, providing alternative solutions. Ontology identifiers are the key for each entity defined in an ontology, and enable a unique and persistent reference to each term. The form of identifiers has been the subject of discussion, which has resulted in a number of different schemes. It is often recommended that identifiers for ontology terms should be semantics-free or meaningless. One practice is to use numeric identifiers, starting at one and working upwards. However, this has a number of disadvantages: it does not allow for concurrent development, is relatively hard to read, and it is difficult to detect errors when an identifier is misused. From the perspective of development, solving these issues could facilitate the process of building and managing ontologies. Here, we suggest random identifiers to enable concurrent development, while exploiting the proquint library to overcome the problems of memorability and pronounceability. Finally, a checksum is implemented to prevent the occurrence of errors while accessing relatively similar identifiers. Availability and Implementation: The software is available from https://github.com/Nizal-Shammry/identitas-j. It has been integrated into environments for ontology development such as Tawny-OWL and Protégé.

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.

Helminth fauna of birds of prey (Strigiformes: Strigidae, Tytonidae) in the Non-Black Earth Region of the Russian Federation

The purpose of the research is studying helminths of carnivorous birds of the order of owls (Strigiformes) found in the Non-Black Earth Region of the Russian Federation.Materials and methods. From 2015 to 2020, complete helminthological dissections were carried out by the Skryabin method for 72 birds of the order of owls after their spontaneous death: 8 specimens of the short-eared owl Asio flammeus, 6 specimens of the Ural owl Strix uralensis, 4 specimens of the little owl Athene noctua, 9 specimens of the barn owl Tyto alba, 19 specimens of the tawny owl S. aluco, and 26 specimens of the long-eared owl A. otus. The study material was provided by rehabilitation centers and veterinary clinics in Moscow City and the Moscow, Tula and Kaluga regions. The helminths were fixed according to generally accepted methods; the species was identified taking into account specific morphological characters.Results and discussion. Total infection rate in owls was 89.9%. All studied birds were found to have mixed infections with two or more types of helminths. We identified 15 helminth species including 3 species of trematodes (Neodiplostomum attenuatum, Strigea falconis, S. strigis), 2 species of cestodes (Cladotaenia globifera, Paruterina candelabraria), 9 species of nematodes (Syngamus trachea, Cyrnea leptoptera, Microtetrameres inermis, Synhimantus laticeps, Porrocaecum depressum, P. spirale, Capillaria tenuissima, Baruscapillaria falconis, and Capillaria sp.) and 1 acanthocephalian species (Centrorhynchus aluconis). For the first time, new hosts were identified for the following helminth species: the barn owl, short-eared owl and little owl for the trematode N. attenuatum, the Ural owl and little owl for S. falconis, the long-eared owl for the nematode S. trachea, the short-eared owl and tawny owl for C. leptoptera, and the tawny owl for M. inermis.

Specialist predation covaries with colour polymorphism in tawny owls

Understanding intraspecific phenotypic variation in prey specialisation can help to predict how long-term changes in prey availability affect the viability of these phenotypes and their persistence. Generalists are favoured when the main food resources are unpredictable compared to specialists, which track the availability of the main prey and are more vulnerable to changes in the main food resource. Intraspecific heritable melanin-based colour polymorphism is considered to reflect adaptations to different environments. We studied colour morph-specific diet specialisation in a generalist predator, tawny owl (Strix aluco), during offspring food provisioning in relation to mammal prey density. We hypothesised that the grey morph, with higher fitness than the brown in Northern boreal conditions, is more specialised in mammalian prey than the brown morph, which in turn has higher fitness than the grey in the temperate zone. We found a higher diversity of prey delivered to the nest by brown fathers compared to grey ones, which also depended on the overall mammalian prey availability. Brown fathers provided proportionally fewer mammalian prey than grey in poor, but not in favourable mammal prey years. Our results suggest that the brown morph is more generalistic and reacts more strongly to variations in food supply than the grey morph, which may be a beneficial strategy in an unpredictable environment caused by environmental degradation. Significance statement Diet choice of a species may vary depending on fluctuations in the abundance of their food resource, but also within a population, there can be adaptations to use different food resources. The tawny owl exhibits a grey and a reddish-brown colour morph and is considered a generalist predator eating both mammal and bird prey. We find that the diet of the reddish-brown morph is more diverse than that of the grey. When the tawny owls’ main prey, small mammals, are abundant both colour morphs prey on mammals, but in years with less small mammals, the reddish-brown morph is more prone of switching to small bird predation than the grey. The generalist strategy of the brown morph is likely to be more favourable than a stricter specialisation in small mammals of the grey under recently reoccurring irregularities in small mammal dynamics.