<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">We investigated the scale and characteristics of spring migration of soaring birds in Bourgas district, SE Bulgaria during three 5-day periods in March (27th-31st), April (20th-24th) and May (12th-16th) 2008. Simultaneous counts were carried out from six observation points in two separate areas (Karnobat and Sredets), located 24.5 km and 37.3 km inland from the Black Sea coast, respectively. In total, 31,049 soaring birds of at least 27 species were counted, by far the most numerous being the White Stork <italic>Ciconia ciconia</italic> (23,358 ind.), followed by the Lesser Spotted Eagle <italic>Aquila pomarina</italic> (3,112 ind.). In Karnobat area, situated farther from the Black Sea coast, the total number of soaring migrants (21,231) was more than two-fold higher than in Sredets area (9,818). Overall, there was a significant difference in flock size and flight altitude within separate area (i.e. among observation points) as well as between the two observation areas and the three 5-day periods. However, there was a substantial variance in factors significantly affecting the flock size and flight altitude among most numerous individual species. In general, birds passed at much higher altitude above Karnobat area (mean flight altitude 208.3 m ± 6.4) compared to Sredets area (mean flight altitude 130.5 m ± 4.4). In both observation areas, northern direction was the most commonly observed flight direction (46.3% of all recorded flight directions). The highest numbers of soaring migrants passed in the late afternoon, between 15.00 and 18.00 hrs - 11,554 individuals (43.0% of all birds counted). The study confirmed that the front of Western Black Sea migration route, or "Via Pontica" as part of the Mediterranean/Black Sea Flyway in SE Bulgaria, is rather wide, since the magnitude of inland migration in Bourgas district can be compared with that along the Black Sea coast, at least during spring migration. Both observation areas qualify as Important Bird Areas (IBA) of European importance according to the several BirdLife International criteria. We recommend that any new wind farms built should avoid the area of Hisar Hill south of Karnobat and the NW parts of Sredets Municipality.</abstract>

National Museum of Natural History, Bulgarian Academy of Science, Tsar Osvoboditel 1, BG-1000 Sofia, Bulgaria

Bulgarian Society for Protection of Birds, jk. Yavorov, bl. 71, BG-1111 Sofia, Bulgaria

Department of Animal Behavior, University of Bielefeld, D-337501 Bielefeld, Germany

Balkani Wildlife Society, Tsanko Tserkovski 67b, BG-1000 Sofia

Characteristics of soaring birds' spring migration over inland SE Bulgaria

<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">The aim of the study was to determine the key environmental factors affecting Scops Owl <italic>Otus</italic> scops occurrence in the wider Kras plateau area (SW Slovenia, 665 km2). Scops Owl was systematically censused in 2006 (180 calling males) and in 2008 (167 calling males). Males were distributed either solitarily or clumped in groups, mostly situated in villages and its surroundings, indicating the species' synanthropic character. Crude densities were 0.3 males/km2 in 2006 and 2008, respectively, while ecological densities were 1.0 males/km2 in 2006 and 0.9 males/km2 in 2008. Population distribution remained roughly the same in both years, with the highest densities in the western and central parts of the Kras plateau, on Kraški rob and on Podgorski kras plateau. Habitat selection was analyzed at three spatial scales (regional, settlement and territory scales), based on spatial data layers (22 environmental variables), using Chi-square goodness-of-fit test and logistic regression. Results revealed that at the regional scale, Scops Owl preferably selected open habitats (extensively managed orchards, built-up areas, vineyards, permanent grasslands) and avoided dense forest and agricultural land with forest trees. As far as settlements were concerned, Scops Owl was more prone to select those that were more distant from the highway, with better preserved traditional agricultural landscape (with more hedgerows) and with higher average annual air temperature. In territory selection, Scops Owl occurrence was associated with longer distance from the highway, larger number of old buildings and higher landscape mosaics. The species seems to be threatened by traffic noise, habitat loss through abandonment and intensification of land and, potentially, by lack of breeding niches within settlements. Conservation measures should include the preservation of mosaic farmland, promotion of extensive agricultural practices, prevention of scrub and forest expansion, and maintenance of breeding niches (old trees, cavities in buildings).</abstract>

The impact of environmental factors on distribution of Scops Owl <italic>Otus scops</italic> in the wider area of Kras (SW Slovenia)

Description of the Short-toed Eagle <italic>Circaetus gallicus</italic> breeding cycle at two sites in SW Slovenia during the years 2010 and 2011

<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">Facultative vertebrate scavengers have an important role in forest ecosystems, however, not much is known as to their use of carrion in temperate forests. Three carcasses of Red Deer <italic>Cervus elaphus</italic> and European Roe Deer <italic>Capreolus capreolus</italic> found dead or killed by Grey Wolf <italic>Canis lupus</italic> were monitored in March and April 2010 and 2011 on Menišija Plateau in northern Dinaric Mountains (central Slovenia) using photo-trapping and video surveillance. Carcasses were monitored for 26 days, during which 708 photos and 43 video recordings of scavengers were taken. In the 91% of all visits recorded, birds were the most frequent scavengers, with Common Buzzard <italic>Buteo buteo</italic> as the most frequent species present at 76% of all visits. On average, Buzzards returned to carcasses twice per day, with an average visit lasting 29 min. Common Buzzards used carcasses to a significantly higher degree on days with snow cover, which was due to the more frequent visits per day and not to longer visits. Recorded antagonistic interspecific interactions suggested that Common Buzzards were the dominant species in the observed avian scavenger guild, as they displaced Ravens <italic>Corvus corax</italic> and Goshawk <italic>Accipiter gentilis</italic> from the carcass. However, Ravens frequently mobbed Common Buzzards while scavenging. Once an Ural Owl <italic>Strix uralensis</italic> also visited prey remains of Grey Wolf, but feeding could not be confirmed. Observations suggested that carcasses of large mammals could be locally and temporarily an important food source for some facultative avian scavengers in Dinaric forests, especially in times when other food is scarce. Data from the two wolf kills also confirm the importance of predation by large carnivores in providing food for scavengers. Given the small amount of meat consumed, kleptoparasitism by solitary raptors did not bring significant losses to large carnivores, whereas gregarious avian scavengers like corvids can importantly affect the consumption process and consume large amount of biomass in a relatively short time.</abstract>

Monitoring of facultative avian scavengers on large mammal carcasses in Dinaric forest of Slovenia

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Acrocephalus

Volume 32 (2011): Issue 148-149 (June 2011)

Characteristics of soaring birds' spring migration over inland SE Bulgaria

The impact of environmental factors on distribution of Scops Owl Otus scops in the wider area of Kras (SW Slovenia)

Description of the Short-toed Eagle Circaetus gallicus breeding cycle at two sites in SW Slovenia during the years 2010 and 2011

Monitoring of facultative avian scavengers on large mammal carcasses in Dinaric forest of Slovenia

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