Winter diet of Long-eared Owls (Asio otus) in the southern Pannonian Plain (Serbia, Vojvodina)

2021 ◽  
pp. 175815592110365
Author(s):  
Filip Tulis ◽  
Nadja Poljak ◽  
Milan Ruzic ◽  
Ján Obuch

Owl diets undergo qualitative changes across the different regions of their area of distribution. During the four winters (from 2014–15 to 2017–18), Long-eared Owls’ pellets were collected at three winterroosts located at the southern part of Pannonian Plain, in the Serbian province of Vojvodina. In 8070 prey items from pellets, we identified 16 mammal and 32 bird species. The Common Vole was the dominant prey species with a proportion in a range from 27.4% to 71.6%. The Muridae family formed a supplementary part of the diet: Mus sp., wood mouse and harvest mouse, during all winters. Birds were also a major supplementary prey during winter 2014–15, comprising 10.6%. A comparison of our results with the diet of Long-eared Owls wintering at the northern Pannonian plain (southwestern Slovakia) indicated an increase the proportion of some species in the southern part. How different land uses in agriculture and environmental conditions may be reflected in the food supply are discussed in relation to the diet composition of Long-eared Owls and an environment whose is richer provides both growing diversity in the diet of these owls and an expansion of their food niche. Our study described the Long-eared Owl as opportunistic predators expanding their food niche in the presence of diversified prey.

Biologia ◽  
2015 ◽  
Vol 70 (5) ◽  
Author(s):  
Filip Tulis ◽  
Michal Baláž ◽  
Ján Obuch ◽  
Karol Šotnár

AbstractOpportunistic predator like the long-eared owl is able to respond to population fluctuations of its main prey. The composition of the winter diet of this owl species was investigated during the period of 13 winters (1992-2000, 2006-2011) in agricultural areas in Slovakia. In total, we found 23 mammal species and 33 bird species (H′ = 0.82) in pellets. The frequency of the dominant prey species, the common vole, varied from 57.7% to 92.4%. Our data show that the abundance of the common vole: (i) had biggest impact on the food niche breadth of the long-eared owl; (ii) when in decline, it was significantly compensated by the increase in the amount of 15 other accessory species (subject to the specific diet offered during the study winters); (iii) was positively correlated with the number of owls in the winter-roost, which varied during the 13 studied winters.


2012 ◽  
Vol 49 (2) ◽  
pp. 107-114 ◽  
Author(s):  
Sylwia Dziemian ◽  
Barbara Piłacińska ◽  
Grzegorz Pitucha

Abstract Diet variation of the long-eared owl (Asio otus Linnaeus, 1758) was investigated on the basis of pellets collected in winter season 2007/2008 from a communal roosting site in a municipal cemetery in Rzeszów (a city in south-eastern Poland). We assumed that the proximity of human settlements would affect the diet composition of this predator, resulting in a higher proportion of species associated with urban habitats. Although voles, especially the common vole Microtus arvalis, were still the most important prey, mice constituted approximately 17% of all prey items, with the field mouse Apodemus agrarius being most frequent. Food niche breadth was wider in December than in March. Our results suggest that owls from Rzeszów hunt mostly in open habitats surrounding the city, where they can still capture their basic prey species. Yet, they can broaden their diet with species of murids associated with the mosaic urban and suburban habitats.


2019 ◽  
Vol 13 (1) ◽  
pp. 139-144
Author(s):  
Filip Tulis ◽  
Tomáš Veselovský ◽  
Simon Birrer

Abstract In winter 2013/2014 a roost of long-eared owls in Bojnice Spa (central Slovakia) was formed by two subgroups situated 12 meters apart from each other. The diets of both subgroups and the direction of the owls’ departure from the roost were studied at monthly intervals. Owls of the Pinus-subgroup left the roost in a significantly different direction compared with the owls in the Picea-subgroup. The common vole was the most hunted prey in both subgroups. However, comparing the alternative prey of the two subgroups, the wood mouse and other mammals were found significantly more often in pellets of the Picea-sub-group, whereas birds were more frequent in pellets of the Pinus-subgroup. Our results suggest that the different prey hunted by the two subgroups may be a consequence of diverging hunting areas with different availability of alternative prey species.


2018 ◽  
Vol 11 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Dávid Szép ◽  
Renáta Bocz ◽  
Jenő J. Purger

Long-eared Owls (Asio otus) usually winter in groups in settlements, hunt at night and rest in evergreen trees during the day. From prey remnants regurgitated as pellets, one can detect species present in their hunting areas and changes in their abundance. Our aim was to reveal how the ratio of small mammal species in Long-eared Owl prey changes during the winter, since weather can influence hunting success and the availability of prey. There were 40–60 Long-eared Owls wintering in the city of Pécs. From November 2014 to mid-March 2015 we collected 6,328 pellets from which 9,087 prey remains were identified. 97.5% of prey consisted of small mammals belonging to 21 species. The diversity of small mammals in the pellets collected in November was significantly lower in comparison with other months. With the increase of precipitation, the relative abundance of the Common Vole (Microtus arvalis) and Common Dormouse (Muscardinus avellanarius) decreased, while that of the Striped Field Mouse (Apodemus agrarius) and Wood Mouse (A. sylvaticus) increased. In the periods when the area was covered by snow, the ratio of the Common Vole as prey continually decreased, probably because it stayed under the snow. Since the availability of the Common Vole declined, the proportions of the Striped Field Mouse and Lesser White-toothed Shrew (Crocidura suaveolens) as alternative prey grew significantly. In low temperature periods, Brown Rats (Rattus norvegicus) and birds are more often preyed upon. Despite the hunting area being predominantly urban, species preferring open grassland habitats were significantly more common. As winter progressed, the role of forest-dwelling species in the diet continuously increased.


Author(s):  
Tomáš Veselovský ◽  
Kristián Bacsa ◽  
Filip Tulis

Based on pellets analysis from five localities in south western Slovakia (Malá Mužla, Malé Ripňany, Obid, Opatovský Sokolec and Tešedíkovo), we studied the diet composition of Barn Owl (Tyto alba) in intensively cultivated agricultural lands. A total of 6218 specimens of prey, 17 mammalian and 7 bird species were identified. The main prey species found in all food samples was the Common Vole (Microtus arvalis), varying between 56 % and 67 %. The proportion of synanthropic species (Rattus norvegicus, Passer domesticus) and species inhabiting agricultural landscapes (Crocidura leucodon, Crocidura suaveolens, Mus sp.) increases in localities with a lower ratio of the Common Vole. The results suggest land use affects the diet of Barn Owls, confirming conclusions which have been drawn in previous studies. From faunistic point of view, discovering the Pannonian Root Vole (Microtus oeconomus mehelyi) in the diet from Malá Mužla was important.


2020 ◽  
Vol 28 (2) ◽  
pp. 37-65
Author(s):  
Adrienn Horváth ◽  
László Bank ◽  
Győző F. Horváth

AbstractIn the present study, we analysed the variation of breeding parameters and the diet composition of the Common Barn-owl (Tyto alba) in three different demographic phases of the Common Vole (Microtus arvalis) in a complete population cycle between two outbreaks. The study was conducted in the south-eastern part of the Transdanubian region in South Hungary. For the analysis, we used data of 81 randomly selected first clutches from 2015 to 2019, a time period which represented a full demographic cycle of the Common Vole after the 2014 outbreak with an exceptionally high peak. We tested the impact of prey abundance and diversity of diet composition as continuous predictors as well as the demographic phase of Common Vole and the mesoregion as categorical explanatory variables on the measured reproductive outputs as response variables using Generalized Linear Models (GLM). Considering the breeding parameters, the number of fledglings, and fledging and reproductive success were significantly higher in the increase phase than during the vole crash phase. Based on GLM models, our results demonstrated that the clutch size of the Common Barn-owl is determined ultimately by the availability and consumption rate of the Common Vole as main prey, while other small mammal prey categories did not affect the clutch size. These results support the finding that the clutch size of vole-eating raptors and owls, which begin breeding periods in early spring predicts the vole abundance in this early spring period. Considering the other investigated small mammal prey groups, the alternative prey role was confirmed only in case of the Murid rodent prey categories (Apodemus spp., Muridae).


2014 ◽  
Vol 62 (3) ◽  
pp. 216 ◽  
Author(s):  
Tamara N. Leitch ◽  
Peter Dann ◽  
John P. Y. Arnould

The endemic Pacific gull (Larus pacificus) is Australia’s largest larid, and though little is currently known of its foraging ecology, its size and wide distribution suggest that it may play an important role within the marine environment. In the present study, regurgitate pellets collected from Seal Island in northern Bass Strait were used to compare intra- and interannual trends in diet composition. The main taxa identified in pellets were the common diving-petrel (Pelecanoides urinatrix), leatherjacket species (Family Monacanthidae), short-tailed shearwater (Puffinus tenuirostris) and mirror bush (Coprosma repens). Analysis of similarity (ANOSIM) identified no significant differences in numerical abundance of the dominant prey species between years, suggesting that the prey base in this region is temporally consistent or that the gulls consume low enough numbers to be unaffected by fluctuation in prey populations. Diving-petrels were consumed in consistently high numbers, suggesting the gulls may be an important predator of this species, or that the gulls are particularly skilled at foraging for them.


Acrocephalus ◽  
2018 ◽  
Vol 39 (178-179) ◽  
pp. 171-176
Author(s):  
Tjaša Zagoršek

Abstract We examined the pellets of the Barn Owl Tyto alba, collected in Pisa, Italy, in 2012. Altogether, 219 specimens of small mammals were found in 85 pellets. The Barn Owl diet was composed of ten species of small mammals, representing three different families (Muridae, Cricetidae, Soricidae). The main prey species was the Wood Mouse Apodemus sylvaticus, followed by the House Mouse Mus musculus and the Savi’s Pine Vole Microtus savii. While the smallest of the small mammals from the area, the Etruscan Shrew Suncus etruscus, was well represented in the pellets, some larger species of small mammals were not represented at all. The reason for such result may lie in the upper limit for our Barn Owl’s prey size. Results suggest that optimal prey weight for our Barn Owl may be between 26–75 g of body mass, however, the prey can be occasionally as heavy as almost 100 g, represented by adult Rat Rattus spp. Nevertheless, our results may not reflect the true hunting strategy of the Barn Owl, but the availability of a certain food item at one point in time.


2019 ◽  
Vol 41 (2) ◽  
pp. 241 ◽  
Author(s):  
Lana Harriott ◽  
Matthew Gentle ◽  
Rebecca Traub ◽  
Ricardo J. Soares Magalhães ◽  
Rowland Cobbold

Established wildlife populations in periurban environments provide an opportunity to spread zoonotic pathogens within human-associated environments. Characteristics of prevalent pathogens harboured by periurban wild dogs suggest that dietary preference could influence their infection status; however, data comparing diet composition and pathogen presence are rarely available. We analysed the stomach contents of 170 periurban wild dogs (Canis familiaris) for the occurrence and biomass of prey items, and then associated this with their known infection status of key zoonotic pathogens. The staple prey items detected were mammalian prey species, most commonly swamp wallabies (Wallabia bicolor) (20.6±6.1%), canines (C. familiaris) (prey) (10.6±4.6%), eastern grey kangaroos (Macropus giganteus) (10.0±4.5%), and deer (various species) (10.0±4.5%). Unidentified bird species (10.0±4.5%) were also common. Wild dogs that were positive for Echinococcus granulosus were significantly more likely to have consumed swamp wallabies. These findings demonstrate the importance of managing both the definitive and intermediate stages of E. granulosus, and suggest that diet correlates with pathogen presence in some cases. This information may assist the development of specific strategies to manage zoonotic pathogens of wild dogs, which are currently lacking.


1992 ◽  
Vol 70 (12) ◽  
pp. 2373-2381 ◽  
Author(s):  
Erkki Korpimäki

Common voles (Microtus epiroticus) were the main prey of Long-eared Owls (Asio otus) breeding in western Finland during 1977 – 1989. They constituted, on average, 58% (range < 15 to > 75%) of the number of prey. Field voles (Microtus agrestis), common shrews (Sorex araneus), bank voles (Clethrionomys glareolus), and water voles (Arvicola terrestris) were the most frequent alternative prey. The owls showed strong preference for common voles over the alternative prey species and this preference increased with vole density. If the common vole is the most profitable prey of Long-eared Owls, the between-years variation in the diet was consistent with the three predictions of the conventional model of the optimal diet theory. (1) Predators should feed on the most valuable prey type when prey are abundant. There was a positive correlation between the abundance of common voles and their proportions in the food. (2) No relationships for alternative prey types agreed with the prediction that the inclusion of a prey type in the diet depends only on the abundance of the preferred prey. (3) As predicted by the optimal diet theory, the diet width expanded when the density of common voles decreased and shrank when vole density increased. Annual breeding density (range 0.0–0.4 nests/km2), mean clutch size (3.0 – 6.3), and mean brood size (0.0 – 3.5) were positively related to the spring abundance of common and field voles. Accordingly, it is adaptive for Long-eared Owls to breed in a good area for voles. Because vole abundances in Fennoscandia fluctuate markedly between years and asynchronously between areas, Long-eared Owls should stay in the same area in the increase phase of the vole cycle, but move away when voles decline.


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