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Documentation of cases of scavenging by Tawny Owl Strix aluco on coypu Myocastor coypus in Italy; highlighting this particular type of feeding behaviour by the species

BackgroundPrior research has shown that the European peninsulas were the main sources of Strix aluco colonisation of Northern Europe during the late glacial period. However, the phylogenetic relationship and the divergence time between S. aluco from Leigong Mountain Nature Reserve, Guizhou Province, China and the Strigiformes from overseas remains unclear. The mitochondrial genome structure of birds is a covalent double-chain loop structure that is highly conserved and, thus, suitable for phylogenetic analysis. This study examined the phylogenetic relationship and divergence time of Strix using the whole mitochondrial genome of S. aluco.New informationIn this study, the complete mitochondrial genome of Strix aluco, with a total length of 18,632 bp, is reported for the first time. A total of 37 genes were found, including 22 tRNAs, two rRNAs, 13 protein-coding genes and two non-coding control regions. Certain species of Tytoninae were used as out-group and PhyloSuite software was applied to build the ML-tree and BI-tree of Strigiformes. Finally, the divergence time tree was constructed using BEAST 2.6.7 software and the age of Miosurnia diurna fossil-bearing sediments (6.0–9.5 Ma) was set as internal correction point. The common ancestor of Strix was confirmed to have diverged during the Pleistocene (2.58–0.01 Ma). The combined action of the dramatic uplift of the Qinling Mountains in the Middle Pleistocene and the climate oscillation of the Pleistocene caused Strix divergence between the northern and southern parts of mainland China. The isolation of glacial-interglacial rotation and glacier refuge was the main reason for the divergence of Strix uralensis and S. aluco from their common ancestor during this period. This study provides a reference for the evolutionary history of S. aluco.

In February 2015, there was a re-search on the number and distribution of the Tawny owl within Protected Natural Monument "Šuma Košutnjak" (Košutnjak Forest). The aim was to deter-mine the nesting population of Tawny owls, as well as the distribution of occupied territories in Košutnjak, which is surrounded by the urban part of Belgrade and under pressure from intensive car traffic. The method was calling and listening. In five evenings, the entire protected area was explored. Using this method, 7 territories of Tawny owls have been determined in the researched area.

Abstract According to Gloger's rule, animal colouration is expected to be darker in wetter and warmer climates. Such environmental clines are predicted to occur in colour polymorphic species and to be shaped by selection if colour morphs represent adaptations to different environments. We studied if the distribution of the colour polymorphic tawny owl (Strix aluco) morphs (a pheomelanic brown and a pale grey) across Europe follow the predictions of Gloger's rule and if there is a temporal change in the geographical patterns corresponding to regional variations in climate change. We used data on tawny owl museum skin specimen collections. First, we investigated long‐term spatiotemporal variation in the probability of observing the colour morphs in different climate zones. Second, we studied if the probability of observing the colour morphs was associated with general climatic conditions. Third, we studied if weather fluctuations prior to the finding year of an owl explain colour morph in each climate zone. The brown tawny owl morph was historically more common than the grey morph in every studied climate zone. Over time, the brown morph has become rarer in the temperate and Mediterranean zone, whereas it has first become rarer but then again more common in the boreal zone. Based on general climatic conditions, winter and summer temperatures were positively and negatively associated with the proportion of brown morph, respectively. Winter precipitation was negatively associated with the proportion of brown morph. The effects of 5‐year means of weather on the probability to observe a brown morph differed between climate zones, indicating region‐dependent effect of climate change and weather on tawny owl colouration. To conclude, tawny owl colouration does not explicitly follow Gloger's rule, implying a time and space‐dependent complex system shaped by many factors. We provide novel insights into how the geographic distribution of pheomelanin‐based colour polymorphism is changing.

The Vistula River is one of the largest European semi-natural rivers of high ecological value that functions as an ecological corridor. To assess the structure of small mammal communities along the Vistula River, an analysis of the diet of an opportunistic predator, the tawny owl Strix aluco, was used. A total of 6355 individuals of 19 species were found, including 5 soricomorph species, 12 rodents, 1 carnivore, and 1 bat species. Tawny owls most frequently caught Apodemus agrarius, Clethrionomys glareolus, Apodemus flavicollis, and Microtus arvalis. Rodents dominated small mammal communities (90%), followed by soricomorphs (8%), and the share of Chiroptera was significant (2%). Using Ward’s method in cluster analysis, three clusters of sites with similar mammal communities were identified. The cluster that included 17 study sites with the dominance of agriculture habitats was inhabited by diverse mammal communities with a high number of species. In the cluster composed of three suburban forest sites, mammal communities had the lowest diversity, although the high species richness and the highest shares of the forest species (A. flavicollis, C. glareolus, and Nyctalus noctula). Mammal communities in the cluster were composed of three urban sites were dominated by A. agrarius and M. arvalis. The study indicates the high species richness of small mammals in floodplains of the Vistula River and the adjacent areas in central Poland. The floodplain offers suitable habitats for species associated with forests, water bodies, agricultural land, and developed areas. The data collected confirms earlier model predictions about the presence of well-connected local populations of forest mammals along the Vistula River.

Abstract Camouflage may promote fitness of given phenotypes in different environments. The tawny owl (Strix aluco) is a color polymorphic species with a gray and brown morph resident in the Western Palearctic. A strong selection pressure against the brown morph during snowy and cold winters has been documented earlier, but the selection mechanisms remain unresolved. Here, we hypothesize that selection favors the gray morph because it is better camouflaged against predators and mobbers in snowy conditions compared to the brown one. We conducted an online citizen science experiment where volunteers were asked to locate a gray or a brown tawny owl specimen from pictures taken in snowy and snowless landscapes. Our results show that the gray morph in snowy landscapes is the hardest to detect whereas the brown morph in snowy landscapes is the easiest to detect. With an avian vision model, we show that, similar to human perceivers, the brown morph is more conspicuous than the gray against coniferous tree trunks for a mobbing passerine. We suggest that with better camouflage, the gray morph may avoid mobbers and predators more efficiently than the brown morph and thus survive better in snowy environments. As winters are getting milder and shorter in the species range, the selection periods against brown coloration may eventually disappear or shift poleward.

Strong numerical and functional responses of owls to voles in cyclic environments are well known. However, there is insufficient knowledge from the boreonemoral region in particular, with depleted populations of small mammals. In this study, we describe the dynamics of the small mammal population in Latvia from 1991 to 2016 and link them to owl population characteristics. We used food niche breadth, number of fledglings, and population trends to lay out the numerical response of six owl species to dampened small mammal population cycles. We found temporarily increasing food niche breadth in tawny and Ural owls. There were no other responses in the tawny owl, whereas the breeding performance of three forest specialist species—pygmy, Tengmalm’s, and Ural owls—corresponded to the vole crash years in Fennoscandia. Moreover, the populations of forest specialist owls decreased, and the change in the Ural owl population can be attributed to the depletion of small mammal populations. We found evidence of a carry-over effect in the eagle owl arising from a strong correlation of declining breeding performance with the small mammal abundance indices in the previous autumn. We conclude that dampening of the small mammal population cycles is an important covariate of the likely effects of habitat destruction that needs to be investigated further, with stronger responses in more specialized (to prey or habitat) species.

Vocal individuality has been used as a monitoring tool, and two criteria are a prerequisite: high variation among individuals and low variation within individuals, and vocal consistency within and across seasons. We examined individual variation in the territorial hoot calls of the tawny owl (Strix aluco) to discriminate between males and to assess a possible conservation technique that would allow for monitoring individuals within a study area. The territorial calls were recorded from five males in the Naejang Mountain National Park in South Korea during the breeding season in 2015 and 2016 and analyzed both quantitatively and qualitatively to determine the amount of variation within and between individuals. Our results showed that the territorial calls were specific to individuals within a population and that the acoustic distances between males living in the same territory during the two years were the smallest for the four nesting sites. Our results suggest that territorial calls of the tawny owls are individually identifiable over two years and that this acoustic technique can be useful for monitoring individual site fidelity.

Established taxa within the Enterobacteriaceae wereisolated from cloacal swabs of Strix aluco chicks in nest boxes located at five research sites. ChromID ESBL medium (bioMerieux) was used to select a pool of Enterobacteriaceae strains producing extended-spectrum beta-lactamases. Drug sensitivity of the chosen strains was determined from the full pool of Enterobacteriaceae to 6 chemotherapeutics of different mechanisms of action. The study evaluated the sensitivity of ESBL-synthesizing isolates to substances belonging to penicillins, cephalosporins, cephamycins, clavams, carbapenems and monobactams. Analysis of the results indicated a potential role of Strix aluco in the dissemination of epidemiologically-relevant Enterobacteriaceae , and, importantly, pose health risks to forest service workers, nature protection service and ornithologists. The results can also serve as the basis for further environmental studies.