Eurasian eagle-owl (Bubo bubo) nesting in a nest box on a very high voltage electricity pylon
In 2008 an Eurasian eagle-owl (Bubo bubo) nestled down for the first time in a wooden nest box with dimensions of 80×80×80 cm, installed on a very high voltage electricity pylon in open agricultural landscape near the village of Budkovce on the Východoslovenská rovina plain in Slovakia. Since 2008 it has nested in this nest box every year, raising 1 and 2×3 young. Nesting by an Eurasian eagle-owl in a nest box on a pylon in agricultural land has not previously been recorded in any part of its whole breeding range. An interesting discovery in 2010 was a clutch of four eggs laid by a common kestrel (Falco tinnunculus) found in the corner of the box, despite the fact that the Eurasian eagle-owls female and chicks were in the nest box.
The latest results of ringing the Lesser Spotted Eagles (Aquila pomarina) in Slovakia
Nine new ringing recoveries of Lesser Spotted Eagles have been collected from abroad and 4 ornithological rings have been successfully read in Slovakia using a monocular up to the end of August 2008. Three of the nine records were from the wintering grounds in Botswana and Zambia (2x), 2 come from a traditional autumn migrating route (Turkey, Israel), 1 ringing recovery represents an autumn spotting in Greece, 1 comes from the spring migration from Turkey and two incomplete records from Hungary. In Slovakia, observation of an adult male shows its fidelity of to the breeding territory even after 6 or 7 years; another male has in his 5th year been nesting 18 km from the site he hatched at. The next observation in Slovakia is represented by a 3 year old non-breeding individual which occured 50 km from the site he hatched at. The final record was of a year old individual that stayed 40 km from the site he originated from. This data suggests that young birds return to Europe right after their first wintering in South Africa.
Štefan Danko, Jozef Mihók, Jozef Chavko and Leoš Prešinský
During consistent monitoring of nesting pairs of Imperial Eagles primarily in Eastern Slovakia it was found that if for some reason the first clutch of eggs was destroyed at the very beginning of nesting, i.e. in late March or the first half of April, the eagles proceeded with substitute nesting. They built a replacement nest, so far always in a different place, in which a new clutch was laid. If the nesting was successful, then as a rule they raised one, and in two cases two offspring.
Jozef Chavko, Štefan Danko, Ján Obuch and Jozef Mihók
In this work we assess the data on the food of the Imperial Eagle (Aquila heliaca) in two separate nesting populations: one in Western Slovakia (21 pairs), the other in Eastern Slovakia (30 pairs). In Western Slovakia between 1978 and 2005 we recorded a total of 562 food items, consisting of 33 species of animal. The species predominantly featuring in the food were the brown hare Lepus europaeus (40.2%), common pheasant Phasianuscolchicus (17.3%), feral pigeon Columba livia domestica (11.7%) and the common hamster Cricetus cricetus (11.6%). In Eastern Slovakia between 1971 and 2005 we identified a total of 524 food items, made up of 30 animal species with slightly varying predominance of the same principal kinds of prey: L. europaeus (29.0%), C. cricetus (27.7%), P. colchicus (8.4%) and Columba sp. (8.2%). Imperial Eagles nesting in Slovakia are affected by the consequences of a marked reduction in population density of steppe-type rodents, especially ground squirrels (Spermophilus citellus) and hamsters (C. cricetus) and have become dependent for their food mainly on the prevalence of other small animals (L. europaeus, P. colchicus) and pigeons (C. livia domestica). Pairs nesting in neighbouring Hungary had similar prey, but a different order of predominance of the species (Haraszthy et al. 1996): C. cricetus (51.0%), L. europaeus (12.0%), P. colchicus (11.6%) and S. citellus (7.4%).
Miroslav Dravecký, Boris Maderič, Ján Kicko, Štefan Danko, Dušan Karaska, Jozef Mihók and Zuzana Guziová
In 2011–201 4 monitoring of the lesser spotted eagle (Aquila pomarina) breeding population was conducted in eight
special protection areas in Slovakia. From a total of 272 successful breeding attempts by 1 49 breeding pairs during 4 breeding
seasons 277 young birds were fledged. The average reproductive success ratio was thus 0.51 juv./pair present, 0.69 juv./breeding
pair and 1 .37 juv./1 00 km2. In the surveyed period a total of 1 51 protection zones were established around the nests in 11 9 breeding
territories, which provided protection for 1 7% of the breeding population of the lesser spotted eagle in Slovakia. By testing
the effectiveness of protection zones it was determined that in nests with an established protection zone the probability of successful
raising of young is higher in comparison with nests without such a zone. The probability that breeding will be successful in the
nests of breeding pairs without a protection zone was 48.1% (95% confidence intervals (CIs): 37.4–59.0%), and in nests with
a protection zone 64.8% (95% CIs: 59.8–69.6%). Among the five most frequent nest tree species used by A. pomarina in Slovakia
for breeding are Picea abies 61 × (28.4%), Pinus sylvestris 45× (20.9%), Quercus sp. 36× (1 6.7%), Fagus sylvatica 25× (11 .6%)
and Abies alba 1 8× (8.4%). Among the rarer nest tree species used are Larix decidua 1 2× (5.6%) and Alnus glutinosa 3× (1 .4%),
while a further 11 species of nest trees did not achieve even 1%. The highest number of nest trees (n = 21 5), i.e. 34 nests (1 5.8%),
was found in the altitude range of 401–450 m a.s.l. and 29 nests (1 3.5%) at 351–400 m a.s.l. Other altitude zones were all below
the 1 0% mark. A total of 54% of nests found (11 6 nests) are located in the altitude zone of 301–600 m a.s.l., and 71 nests (33%)
in the zone 600–900 m a.s.l. The lowest situated nest was at an altitude of 1 50 m and the highest at 950 m; the average was
595.01 m a.s.l. The highest number of nests (n = 209) were located on trees in a range 1 5.1–20.0 m above the ground (n = 92,
44%), while the lowest nest found was at a height of 5 m and the highest at 30 m above the ground.
Ján Obuch, Štefan Danko, Jozef Mihók, Dušan Karaska and Ladislav Šimák
A Central European subspecies of the Ural owl Strix uralensis macroura (Wolf, 1810) is widespread in the territory of Slovakia. The work presents unpublished data on the diet of this subspecies from several territorial units of eastern and northern Slovakia, obtained from pellets and the nest linings in boxes (1 ,564 pieces). There is less data about prey brought to young in the nest but still not yet consumed (137 pieces). Published data from analysis of the stomachs of dead and shot owls come from the first six decades of the 20th century. Together with existing published data, 2,134 pieces of the diet of S. uralensis from Slovakia are evaluated. They indicate the dominance of non-forest species Microtus arvalis and a more plentiful representation of larger species of prey: Lepus europaeus, Sciurus vulgaris and Corvus sp. In upper Orava the diet of young S. uralensis also consists of frogs Rana temporaria, moles Talpa europaea and mountain species of rodents: Microtus agrestis, M. subterraneus, Sicista betulina and Arvicola amphibius. In data from the mountains of central Slovakia the Clethrionomys glareolus has high abundance, and in eastern Slovakia the Apodemus flavicollis and A. agrarius are more represented, and in the lowlands also the Cricetus cricetus. Upon evaluation ofmaterial from the entire breeding grounds of S. uralensis it can be deduced that the basic diet consist of mammals (88.6%) from the orders Soricomorpha and Rodentia. In the countries of Central Europe the species M. arvalis, M. subterraneus, A. flavicollis and Muscardinus avellanarius are more abundantly represented, and in the Baltic states the species Sorex araneus, M. agrestis, M. oeconomus and M. rossiaemeridionalis. The species S. betulina and A. agrarius occur in the diet of S. uralensis from Central Europe up through the Far East.
Jozef Chavko, Roman Slobodník, Lucia Deutschová, Ján Lipták, Jozef Mihók, Ján Obuch and Vladimír Nemcek
From October 201 0 until December 201 4 the LIFE09 NAT/HU/000384 project was implemented in four Special Protected Areas in Slovakia. The recent project was complementary to a previous LIFE project implemented between 2006 and 201 0. Both projects supported regular monitoring of the population of saker falcon and new approaches to conservation of the species. The LIFE09 project helped to increase knowledge about the prey composition and the behaviour of the species. The population was strongly affected in 201 3 by extremely bad weather conditions (1 .79 fledglings/breeding attempt). Although the total number of saker falcon pairs in Slovakia is thought to be higher, 31 pairs were breeding in 201 4. By analysis of the diet (2991 individuals), 47 prey species were identified, from which birds were predominant (80%). More than half of the diet consisted of feral pigeons (Columba livia f. domestica) (59%)
Jozef Chavko, Lucia Deutschová, Štefan Danko, Jozef Mihók, Bedrich Landsfeld, Jirí Pavelka, Ladislav Šnírer, Stanislav Harvancík, Andrej Dubravský, Leonidas Prešinský and Richard Galaš
Between 1 977 and 201 3 nesting of 72 different pairs of imperial eagle was recorded in Slovakia. The nesting population in Slovakia is concentrated in two subpopulations with the nesting area distant about 200 km. In Eastern Slovakia nesting of 42 pairs was recorded whilst in Western Slovakia 30 pairs were nesting. Authors present results of 37 years period of survey focused on distribution and trend of nesting population, as well as habitat preferences of the species. The paper compares results from Western and Eastern Slovakia. From Western Slovakia further data are evaluated, such as threats negatively influencing the population, period of hatching and other aspects of nesting biology. During the survey period the number of known nesting pairs in Slovakia has increased from five in 1 977 to 53 in 201 3. In total, 908 nesting events have been recorded during this period with 642 successful nesting events and 1 ,080 fledglings. In Western Slovakia the pairs prefer foothills, whilst in Eastern Slovakia most of the pairs nest in lowlands. Strong anthropic pressure is significantly influencing the distribution and size of the population as well as the habitat preferences of the species.
Miroslav Dravecký, Štefan Danko, Ervín Hrtan, Ján Kicko, Boris Maderič, Jozef Mihók, Miloš Balla, Tomáš Belka and Dušan Karaska
In the years 2009-2012 a total of 316 individuals were marked in a colour ringing programme of the population ofA. pomarina in Slovakia. From this a total of 39 inds. were ringed with yellow readable plastic rings with a two-place alphanumeric code (all young in a nest) and 277 inds. (273 young and 4 adult inds.) with light-blue rings. For the entire period of the programme of marking the A. pomarina population in Slovakia in the years 2000-2012 a total of 952 inds. were ringed, 933 of which were young birds in nest and 19 adult individuals. In the period 2009-2012 48 records were obtained from observations of 35 individuals of different age categories (31 individuals from one to 11 years old, three of unknown age and one young individual about one month after fledging the nest). The age categories of immature individuals were determined, and six were found to be one-year-old individuals (12.5%) in the second calendar year of life after their first return from wintering grounds, six were two-year-old eagles (12.5%) and five were three-year-old eagles (10.4%) which spent breeding periods in Europe at a relatively small distance from their place of hatching. Adult individuals were found to be in their current breeding grounds at distances of 8-249 km from their hatching place. In the period 2000-2012 three individuals were recorded 3× and four individuals 2×. The results confirm breeding site fidelity in adults, but also the fidelity of immature individuals to their hatching place, and the return of one-year-old individuals from their wintering grounds to the vicinity of their hatching place immediately in the first year of life (that is, in the second calendar year).