Search Results

1 - 10 of 48 items :

  • "breeding density" x
Clear All

Gnezditvena gostota velikega skovika Otus scops v naseljih otoka Brača (srednja Dalmacija)


Between 1984 and 2017, 1,388 Black Kites were recorded, mostly in lowlands with 70% of observations made at Dravsko polje. They were observed from sea level to around 1,600 m a.s.l. with an average elevation of 271 m a.s.l. The species was present in Slovenia from mid-March to early December with indistinct spring and autumn migrations. The highest number of observations was recorded in May. The Black Kite was observed in 71 out of 238 10x10 km grid squares in Slovenia (29.8%), with more observations around known breeding sites and at sites with higher observer effort. Both the number of observations and the number of probable and confirmed breeding pairs increased. In 2011–2018, 10 breeding pairs were found at 7 sites (3–7 per year). Additionally, 11 probable breeding pairs at 9 sites (0–6 pairs per year) were found. The breeding population in 2011–2018 is estimated at 10–21 pairs with an average breeding density of 0.3–0.9 breeding pairs per 100 km2. The highest density was recorded at Dravsko polje with 0.6–2.2 breeding pairs per 100 km2. If possible breeding (breeding attempts) were also taken into consideration, the estimate would be up to five breeding pairs higher. The species was recorded at known breeding sites in most years after the breeding was confirmed. Black Kites were observed closer to larger water bodies and to rubbish tips than expected by chance. More Black Kites were recorded in areas with a lower percentage of forest and arable land and a higher percentage of meadows, settlements and wetlands.

: 59-68. Bossema, I., Röell, A. & Baeyens, G. (1986): Adaptations to interspecific competition in five corvid species in the Netherlands. - Ardea 74: 199-210. Chamberlain, D.E., Cannon, A.R., Toms, M., Leech, D., Hatchwell, B. & Gaston, K. (2009): Avian productivity in urban landscapes: a review and meta-analysis. - Ibis 151: 1-18. Cramp, S. & Perrins, C.M. (ed.) (1994): Handbook of the Birds of Europe, the Middle East and North Africa. The birds of the western Palearctic. Vol. 8. Crows to Finches. - Oxford University Press, Oxford. Dolenec, Z. (2000): Breeding

. (ed.): Rapaces Nocturnes. Actes du 30e Colloque interregional d’ornithologie, Porrentruy (Suisse), 2, 3 et 4 novembre 1990. Prangins, Switzerland. - Societe romande pour l’etude et la protection des oiseaux. (in French) Vasović, M. (1988): Kopaonik - Geografska monografija. - Stručna knjiga, Beograd. Vrezec, A. (2003): Breeding density and altitudinal distribution of the Ural, Tawny and Boreal Owls in North Dinaric Alps (central Slovenia). - Journal of Raptor Research 37 (1): 55-62. Vrezec, A. & Tome, D. (2004): Habitat selection and patterns of distribution in a


We analysed the population size, population dynamics and reproduction success of the lesser spotted eagle in Latvia from 1988 to 2014. While the overall population did not show a statistically significant trend during any of the periods analysed (long, medium and short term), the populations in the individual study areas changed differently: of five research plots, populations were stable in two, increased in one, and decreased in two research plots. Using the existing research plots as samples of breeding numbers in areas of different breeding density classes based on forest management units, the total breeding population in Latvia was estimated. The overall number of breeding pairs in 2012-2014 was between 3700-4000. During the period 1988-2014, 65.62% of all pairs recorded as present on their home range, made a breeding attempt and laid eggs. The reproductive success ratio was 0.49 young per occupied territory with an adult pair of birds and 0.74 young per breeding pair which laid eggs. Overall, during the 21 -year research period there was a stable long-term trend in reproductive success (young per pair present on home range). Rarely, indeed only in 1 .89% of all cases did two young fledge. The total number of young (young per 100 km2) shows stable long-, medium- and short-term trends with an average value of 5.1 young per 100 km2.


The Barn Owl (Tyto alba) bred in 15 UTM squares (75%, n = 20) of the Kazanlak Valley (central south Bulgaria) at 33 localities (55% confirmed, 12% probable and 33% possible breeding). Its distribution in the Valley was found to be five times larger and its population size ten times greater during our study period than previously thought. Evidence of one to five breeding localities (mean 2.2±1.3) was detected in each occupied UTM square. A breeding density of 4.1 bp/100 km2 was close to the average in Central Europe. Nests inside or on metal frames and ducts were typical in the region and gave possibility for its successful breeding in most of the habitable buildings. The Barn Owls were breeding mainly in poorly maintained and abandoned buildings whose supply has not decreased markedly since the agricultural restoration started in Bulgaria after it joined the European Union and intensive industrial agriculture has resumed with EU support. Currently, it appears that Barn Owl is not threatened by a ‘housing shortageʼ over the next decade.

.si/~opoljanelj/projekti/gozdna_pot/index-gup.htm], 28/12/2016. Vrezec A. (2003): Breeding density and altitudinal distribution of the Ural, Tawny, and Boreal owls in North Dinaric Alps (Central Slovenia). - Journal of Raptor Research (37) 1: 55-62. Vrezec A . ( 2000): Z godnje g nezdenje l esne s ove (Strix aluco) blizu urbanega središča Ljubljane. Acrocephalus 21 (98/99): 81-82. Vrezec A., Saveljić D. (2006): Breeding density of Tawny Owl Strix aluco territories in montane forests of Mountain Bjelasica (Montenegro). - Ciconia 14: 41-47. Vrezec A., Tome D. (2004a): Altitudinal segregation between Ural Owl Strix


The Peregrine Falcon (Falco peregrinus) is the most widely distributed bird species in the world, but very little is known about its tropical populations, where even very basic information (e.g. about population density) is mostly lacking. In January 2017, 2018 and 2019, we conducted three intensive surveys amounting to 27 days and 5,400 km driven by car in West Malaysia at latitudes between 3 and 7 °N, where the ernesti subspecies was confirmed to be a resident breeder only as recently as 1996. Here, we summarize our findings and combine them in a synthesis that includes all published and unpublished records of nesting peregrines that we could obtain in that area. In particular, we draw on the foundational work conducted by our late colleague Laurent Molard in 2003–2005. We give information about breeding habitats, local density, behavior and breeding phenology. We also describe and discuss our use of call playback during the surveys. Much more extensive reports for each survey, with plenty of photographs of all sites visited, are available upon request from the authors.

According to current knowledge, Peregrines in West Malaysia nest mainly in cliffs, with some nesters on buildings exceptionally found (in Kuala Lumpur and suspected also elsewhere in cities) and possibly on large towers. Virtually all natural nesting places are limestone mountains with vertical cliffs. Owing to the mostly flat terrain in West Malaysia, with limestone cliffs only occurring very locally, the peregrine breeding distribution is extremely patchy. We found local aggregations in the regions of Ipoh (Perak), Gua Musang (Kelantan) and in the state of Perlis. However, local density is fairly low even in these hotspots, with nearest-neighbor distances in the densest cluster ranging from 3.7–5.6 km (mean 4.7). Overall, by the end of 2019, 36 occupied sites had been found in West Malaysia, of which 10 were known before 2003, 9 were found during the surveys by Mo-lard and his colleagues in 2003–2005, and 17 were new discoveries during our surveys in 2017–2019. In West Malaysia, the start of egg-laying appears to be late January and early February. We found playback of the ‘eeechup’ courtship calls to be extremely helpful when locating pairs. Playing a 26-sec sequence twice enticed the majority of birds to become airborne and/or to call, which greatly increased their detection probability and therefore survey success.

In spite of the great increase in the number of known peregrine sites owing to our surveys, the currently known number of pairs is still considerably lower than the estimate by Molard et al. (2007) of 70–80 pairs. Although this latter may perhaps be a slight overestimate, we are convinced that many more pairs remain to be discovered in cliffs, where most of the future survey effort should be concentrated. This will then also provide the basic knowledge required to protect limestone outcrop sites, e.g. from quarrying activities, which may destroy entire limestone hills. However, we believe that the major uncertainty about the size of the population of nesting F. p. ernesti in Malaysia arguably comes from the population segment of nesters on buildings, which is likely underestimated and hard to survey and even discover in the first place. Moreover, given the rate of increase of nesters on buildings in other parts of the world, it is likely that the proportion of pairs nesting on buildings will increase also in Malaysia. Hence, we believe that new pairs will be discovered in the future also where there were none in earlier years.

Gnezdilke Kopenskega dela Zadrževalnika Medvedce (SV Slovenija)


Agriculture has a great impact on biodiversity in Europe. Populations of farmland birds are declining due to both intensification and abandonment of agriculture. The purpose of this study was to determine the effects of overgrowing on the diversity of birds at Cerknica Polje. Six vegetation types were identified on eight survey plots (15.2-31.6 ha each): Short grass - regularly mown wet meadows; Tall herbs - stands of Common Reed Phragmites australis and Reed Canary Grass Phalaris arundinacea; Sparse bushes - stands of low woody plants; Dense bushes - dense stands of bushes; Meadows with trees - mown meadows with scattered trees; Bushes with trees - hedges, trees and dense stands of bushes. In total, 34 species were registered. The heterogeneity of vegetation types correlated positively with the heterogeneity of bird species. The highest density of breeding territories and species was established in Bushes with trees, the lowest in Short grass. No species were registered in all vegetation types, and only Tree Pipit was recorded in five out of six types. Twelve species were registered in only one vegetation type. Cerknica Polje is an important breeding locality for species with the highest breeding density at the national level (e.g. Corncrake Crex crex, Curlew Numenius arquata, Skylark Alauda arvensis, Whinchat Saxicola rubetra, Sedge Warbler Acrocephalus schoenobaenus). These species breed in specific habitats with different stages of succession. A managing plan for the area should therefore combine abandoned plots in different stages of succession and large regularly mown areas. Abandonment of agriculture at Cerknica Polje has led to the emergence of areas with bushes in different succession stages. Efforts should be directed at preserving large complexes of mown wet meadows.