Latest data on distribution of the Pygmy Owl (Glaucidium passerinum) in Bulgaria and Slovakia including population density comparison The authors provide an outline of actual knowledge on the distribution of the Pygmy Owl (Glaucidium passerinum) in Bulgaria from 1900 until 2008. The most recent estimates of the species population in Bulgaria are 150-200 and in Slovakia 1500-2000 breeding pairs. On the basis of quantitative samples obtained in the Rila Mts (Bulgaria) and in the High and Western Tatra Mts, Low Tatra Mts, "Krivánska Malá Fatra" Mts, "Veľká Fatra" Mts, "Chočské vrchy" Mts, "Stolické vrchy" Mts (Slovakia) obtained densities in Bulgaria are compared with ascertained densities in similar elevations in Slovakia. In the Rila Mts, 9 territories were found / 23 km2 and average density 0.39 territories / 1 km2 was found, in 1350-2000 m elevation. In Slovakia 75-82 territories were found / 79 km2 and average density 0.95-1.04 territories / 1 km2 was found, in 800-1650 m elevation. The density of Pygmy Owls in the mountains of Bulgaria is twice as low as in the mountains of Slovakia in Western Carpathians. This is probably caused by the distribution at the edge of the distribution area of the species and an higher isolation level in the Balkans. Other evaluated factors, such as habitat quality, health of forest stands, shorter twilight and shorter owl activity in the Balkans than in the Carpathians, negative effect of streams on voice activity of the Pygmy Owls, lack of food supply or lack of breeding holes, or even possible competition with other owl species were not regarded as reasons causing differences in Pygmy Owl densities in compared areas.
Data on the food of the Eurasian pygmy owl in Slovakia was collected in 1999−2014 at 12 breeding locations in 7 mountain ranges of the Western Carpathian Mts and 1 range belonging to the Eastern Carpathian Mts. The basis of the evaluation of the food spectrum of prey of G. passerinum was the collection of pellets, osteological remnants and feathers from birds beneath nest cavities and roosting places of females in the months of May to July, that is, in the period of feeding young in the nest. Overall samples of food from 12 nests at elevations of 650−1,260 m a.s.l. were collected; from the largest of the three nests in the upper Nitra Region, from one nest in the Západné Tatry Mts and from three nests in the Volovské vrchy Mts. We compared these data with existing published data from Slovakia. A higher share of birds (65.0%) was found in the obtained material than mammals (34.8%). In the samples from 12 locations 10 species of mammals and 33 species of birds were found among the 377 individual prey samples. Among mammals, forest species of rodents predominated: Clethrionomys glareolus (22.8%) and Apodemus flavicollis (6.6%). The species Microtus arvalis (2.7%) was less abundant than in the stores of food from the Chocské vrchy Mts (35.4%). From the broad spectrum of songbirds, no species exceeded a presence of 7%. Species from the families Sylviidae, Turdidae, Paridae and Fringillidae were more numerous, while the species Phoenicurus phoenicurus, Motacilla alba, Carduelis cannabina, Dendrocopos minor and Passer domesticus were among the more uncommon prey. In total 582 individual prey were determined from the food remnants of G. passerinum in Slovakia (present study and other published studies). The species Clethrionomys glareolus occurred with a higher dominance than average in the pellets of G. passerinum in the mountains which border the region of the upper Nitra. In the Belianské Tatry Mts the most abundant rodent species was Terricola subterraneus, while in the mountains of eastern Slovakia the yellow-necked mouse Apodemus flavicollis was most often hunted, and of the songbirds, the coal tit Periparus ater. Among songbirds hunted near the breeding grounds of G. passerinum in the Považský Inovec Mts the collared flycatcher Ficedula albicollis was the most numerous. Among the most numerous songbirds which are evenly represented in all compared areas were: Regulus sp., Certhia familiaris, Poecile montanus and Cyanistes caeruleus.
Accessible data on 78 breeding occurrences of the Eurasian pygmy owl (Glaucidium passerinum) in Slovakia are evaluated. Data from the oldest known breeding in 1846 up to 2010 were used. The breeding of this species has been proved in 24 orographic units, at altitudes from 450 (400) to 1450 m. Distribution of the species in Slovakia closely follows the distribution of fir (Abies alba) and spruce (Picea abies) and breeding has also been recorded in forest habitats with an abundance of scots pine (Pinus silvestris) and black pine (Pinus nigra). From the point of view of natural and secondary origin of these forest habitats, the species breeds in both 'natural' habitats such as montane spruce forests and Euro-Siberian coniferous forests, forests with beech and fir, oak-hornbeam forests with lime and fir, as well as in secondary forest spruce plantations. From 22 evaluated Slovakian nests as many as 17 (70.8%) were situated no farther than 200 m from water. A high number of nests (72.5%) were situated at altitudes between 600-1100 m, with 13% above this range and 14.5% below. As many as 25 nest holes were located in spruce, both living and dead, and in snags, ten in fir (with a significant number of dead stumps), six in beech, four in oak and four in aspen. Nests were also found on one occasion each in larch, maple and black pine. On one occasion breeding took place in a nest-box. On several occasions the same nest hole was used repeatedly, with the highest number of such occasions being four times in the same tree in an eight year period. On three occasions a shift of nest location of ca. 200-350 m within the same territory occurred and two neighbouring pairs, and nests, were once found at the same time just 400 m from each other. Nest holes excavated by the Dendrocopos major and Picoides tridactylus are often used. On four occasions breeding took place in natural cavities (2× beech, 1× larch, 1× maple). The lowest situated nest was placed lower than one m above ground level and the highest 13 m above the ground. From 44 evaluated nest holes the highest number (26) were situated between 4-7 m. The production of young was evaluated in 57 cases, 34 of which were successful (69.7%). Young were found on 27 occasions, from which 80 fledged: an average of 2.96 per nest. This average is slightly lower than that calculated in Austria and Germany. In the colder than usual years of 2009 and 2010, which were poorer in food availability and characterized by high precipitation, the numbers of fledglings was even lower: on average only 2.3 and 2.0 fledglings per nest respectively. The average number of fledglings per nest from 8 Slovakian nests in three consecutive years (1989 to 1991) was 3.75 fledglings per nest but the same parameter from nine Slovakian nests in six years (2005 to 2010) dropped to 2.88. This indicates a diminishing trend in nest productivity. On one occasion the movements of fledglings in the territory after their fledging were observed for 27 days. On other occasions disturbance due to human activit...
Knowledge about spatial distribution of owl species is important for inferring species coexistence mechanisms. In the present study, we explore spatial patterns of distribution and habitat selection of four owl species – Eurasian pygmy owl (Glaucidium passerinum), boreal owl (Aegolius funereus), tawny owl (Strix aluco) and Ural owl (Strix uralensis) – ranging in body mass from 50 g to 1300 g, with sympatric occurrence in temperate continuous montane forests in the Veľká Fatra Mts., Western Carpathians, central Slovakia. Locations of hooting owl males were surveyed between 2009–2015 in an area of 317 km2. Spatial point pattern analysis was used for analysis of owl distribution. Random patterns of owls’ spatial arrangement dominate at both intra‐ and interspecific levels within the studied area. Only intraspecific distribution of pygmy owls and interspecific distribution of Ural owls toward tawny owls exhibited positive associations. This discrepancy with other studies can be explained in terms of pygmy owls’ preference for high‐quality nest sites and/or spatial clustering in their prey distribution, and due to aggressive behaviour of dominant Ural owls toward subdominant tawny owls, respectively. Moreover, we found considerable overlap in habitat preferences between owl species, considering stand age, stand height, tree species richness, distance to open area, elevation, slope, percentage of coniferous tree species and position on hillslope, although pygmy owls were not registered in pure broadleaved stands, Ural owls were not registered in pure coniferous stands, and boreal and Ural owls were more common on slope summits and shoulders than tawny and pygmy owls. The observed patterns of spatial arrangement might suggest developed coexistence mechanisms in these owl species; differences between studies may indicate complex interactions between intra‐ and interspecific associations and habitat quality and quantity, food availability and owl species involved in those interactions on a landscape scale.
. © Raptor Protection ofSlovakia (RPS) 37 Nesting by the Eurasian eagle owl (Bubo bubo) in a nest of the whitetailed eagle (Haliaeetus albicilla) Hniezdenie výra skalného (Bubo bubo) v hniezde orliaka morského (Haliaeetus albicilla)Samuel PAČENOVSKÝ, Peter CHRAŠČ & Matej REPEL Abstract: In 2011 and 2012 two breedings by a pair of Eurasian eagle owls were observed in an old white-tailed eagles' nest at Blatná Polianka in the Senianske rybníky SPA. The nest was situated in a grey poplar tree 15-20 m above the ground in a treebuffer by the rivulet Okna, in open lowland landscape without woodland, just with linear tree vegetation and scattered trees. In 2011 incubation of the clutch was observed and the female was present in the nest even at the end of April, when the fledglings were probably already present in the nest, but no more data on their further success were obtained. In 2012 the pair of Eurasian eagle owls bred in the same nest again, but in May the nest was already abandoned and we suppose predation of the clutch, probably by ravens. This occasion is the third known breeding attempt by the Eurasian eagle owl in a raptor nest built in a tree, and the first known occasion of breeding in a white-tailed eagles' nest in Slovakia. The obtained data also document the further spreading of the species in the Dolný Zemplín region into unusual habitats of a lowland agricultural landscape with very few trees.
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