Крупные пернатые хищники степных котловин Байкальского региона, Россия
Methods In 2005 we have continued the surveys of raptor populations in Siberia which had been started in 1999. In this season a field group of the Field Research Center surveyed the Baikal region (24 June -21 July 2005). The total length of survey routes was 5322 km. We set 4 study areas with a tota...
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Общество с ограниченной ответственностью «Сибэкоцентр»
2006
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| Summary: | Methods In 2005 we have continued the surveys of raptor populations in Siberia which had been started in 1999. In this season a field group of the Field Research Center surveyed the Baikal region (24 June -21 July 2005). The total length of survey routes was 5322 km. We set 4 study areas with a total area of 2125.63 km2 for monitoring the raptor numbers in the Baikal region (table 1, fig. 3). The Baikal region is a large territory in Eastern Siberia near the Baikal Lake. The region includes mountains and steppe depressions in the river valleys. Analysis of satellite images Landsat-7 ETM+ used to create the detailed map of steppe depressions. Different types of steppe depressions have been distinguished with use of landscape criterion and vegetation index (fig. 2). The total area of the steppe depressions in Baikal region is 44027.47 km2 (table 1). The found breeding territories of raptors were GPSed and mapped using GIS software (ArcView 3.2a, ESRI, CA, USA) for the subsequent calculation of the density (Karyakin, 2000, 2004). The study areas include all types of rocks, steppes and forests, which are very character for the surveying territory (fig. 2, 3). A number of species noted to breed in a study area was extrapolated for the total area of the steppe depression with similar landscape and vegetation conditions. Results of studies Golden Eagle (Aquila chrysaetos) We found 9 breeding territories in steppe depressions of the Irkutsk district and the Republic of Buryatia, 8 from which were located on study areas. One active nest of the Golden Eagle located on a pine tree was found on 30 June in the Irkutsk district. A total of 15-20 pairs are estimated to live in the steppe depressions of the Irkutsk district. We found 8 breeding territories in steppe depressions of the Republic of Buryatia (fig. 4), 7 from which were located on study areas. The distance between the nests was 11.4±5.3 km (n=3; 5.4-15.1 km) (M±SD, lim.). The density in the steppe depressions was 0.26 0.73 pair per 100 km2, averaged 0.57 pair per 100 km2. A total of 80-100 pairs are estimated to live in the southern steppe depressions of the Republic of Buryatia (15532.10 km 2). All nests were located on trees: on a pine (5) and a larch (1). The brood size averaged 1,4±0,55 (n=5; 1-2). Imperial Eagle (Aquila heliaca) We found 29 breeding territories and 11 living nests of the Imperial Eagle. Eleven breeding territories were found in the Balagano-Nukutskaya forest-steppe, 10 from which were located on the study area № 1 (fig. 5). The density of the breeding territories of the Imperial Eagle in the Balagano-Nukutskaya forest-steppe was 1.4 per 100 km2. The distance between the nests was 8.05±3.51 km (n=11; 2.51-13.66 km). Only 6 nests from 11 (54,55%) were occupied, and breeding was noted only in 5 nests, and only 4 nests (36,36%) were with chicks. Five breeding territories were identified as abandoned. The density of the active nests of the Imperial Eagle in the Balagano-Nukutskaya forest-steppe was 0.84 per 100 km2. A total of 90-100 pairs are estimated to live in the Balagano-Nukutskaya forest-steppe and 96-112 pairs in the all steppe depressions of the Irkutsk district. The decreasing of raptor numbers is about 40%. Surveyed 6 living nests in the Irkutsk district were with broods included 1-2 chicks, averaged 1.5±0.6 chicks per successful nest (1.13 chicks per an active nest and 0.56 chicks per breeding territory). We found 13 breeding territories in steppe depressions of the Republic of Buryatia, 10 from which were located on study areas (76.9% breeding territories we found in the Ivolga steppe depression). The density in the Ivolga steppe depression was 2.57 pairs per 100 km2. The density of active nests of the Imperial Eagle was 2.05 per 100 km2. The distance between nests was 5.1±1.5 km (n=9; 2.9-7.1 km). Successful breeding was registered only in 46.2% of breeding territories on the Republic of Buryatia. A total of 150-176 pairs are estimated to live in the all steppe depressions of the Republic of Buryatia (82.7% pairs in the Ivolga steppe depression). The average brood (n=4) size was 1.75±0.5 chick per successful nest (0.7 chick per occupied nest and 0.54 chick per surveyed nest). We found 2 broods in 3 nests, 1 fledgling in a nest and 2 active nests were not visited. Recorded nests (n=37) were located on pines (81.08%) on larches (18.92%), by the way all nests noted on larches were noted only in the Baikal region. The nests noted on pines were settled on single trees, in deep forest (about 150 m far from the edge of forest) (13,51% each) and on edges of forest (72.97%). 56,7% nests were built up on a top of pines, 40,0% in a brunch fork under the top of tree, and a nest was in a brunch fork of upper third part of a tree. The nests noted on larches were built up in a brunch fork in the upper third part of a tree (42.9%), in a brunch fork under the top of tree and in the base of branches (28.6% each). Steppe Eagle (Aquila nipalensis) We recorded 3 breeding territories on the study area №1 in the Irkutsk district. A pair of the Steppe Eagle occupied an old nest of the Imperial Eagle and noted near it. Two another pairs were recorded in more typical places for Steppe Eagles on mountains with cliff-faces. We found empty nest in one of territories with signs of previous year breeding. The density was 0.42 pair/100 km2. The distances between the centres of breeding territories were 4.28 and 14.23 km. The all registrations of Steppe Eagles were on the territories, where Imperial Eagles were absent by different reasons. We project 5-10 breeding pairs of the Steppe Eagle for the Irkutsk district. We found 8 breeding territories in the republic of Buryatia, 5 of which were surveyed in study areas. The highest number of Steppe Eagle was noted in the Borgoyskaya steppe, were 62,9% of local population breed. The average distance between breeding pairs was 13.6±1.8 km (n=3; 11.6-14.9 км). We found a dead clutch contained 2 eggs in a nest and broods contained a chick per each in 4 nests. Great Spotted Eagle (Aquila clanga) An adult bird was recorded in wetlands of upper reaches of the Chalyuta river in 6 km to north-west from Ivolginsk on 8 July 2005. White-Tailed Eagle (Haliaeetus albicilla) An adult bird was observed on the right side of the Selenga river near the lower reaches of Itantsa river on 8 July, 2005. Booted Eagle (Hieraaetus pennatus) We surveyed the Booted Eagle in 6 places in the Irkutsk district, 2 of which were identified as breeding territories, 2 as probable breeding territories, and in 4 places in the Republic of Buryatia, the breeding is projected for one territory (fig.7). The distance between breeding territories was 32.5 km in the Balagano-Nukutskaya forest-steppe and 26.5 km in the Tugnuyskaya depression. The density was 0.25 pair/100 km2 (0.14 pair/100 km2 including the study areas, where birds were not recorded). Following the records of auto routes (perpendicular distance was 1 km) the density was 0.19 pair/100 km2. We project 62-83 pairs of the Booted Eagle to breed in the steppe depressions of the Baikal region. Nests of the Booted Eagle recorded in Balagano-Nukutskaya forest-steppe were on larch trees in the isolated forest in 30 and 60 m far from edges. The nest near Elantsy village was built up on a pine tree and located on a slope of the ravine in a segmented forest in 1 km far from a steppe valley. Upland Buzzard (Buteo hemilasius) We found the Upland Buzzard breeding in the Balagano-Nukutskaya forest-steppe, valleys of the Kuda and Selenga rivers, the Ivolginskaya, Tugnuyskaya and Chilokskaya depressions, around the Gusinoe Lake and in the Borgoyskaya steppe. The average density was 1.83 pair/100 km2 (1.12-2.93 pairs/100 km2). The average distance between nests was 5.56±3.83 km (n=45; 1.42-17.36 km). Under optimal conditions without heavy press of eagles Upland Buzzards breed with the distance 3-6 km between pairs. The increasing or decreasing of density in some territories is impacted by limits of suitable places foe nesting and competition with eagles (Fig. 7, 10). The density of the Upland Buzzard is inverse proportional to the density of eagles. The heaviest competition for nesting places is noted with the Imperial Eagle, which connected with preferring these two species similar places for nesting edges of forests. During our surveys 9 breeding territories were found in the Irkutsk district and 43 territories in the Republic of Buryatia. The density of the Upland Buzzard is 1.12 breeding pairs/100 km2 in the Balagano-Nukutskaya forest-steppe, the average distance between nests is 6.69±5.1 km ((n=7; 1.67 15.35 km). A total of 110-140 pairs to live on this territory, and the number has stable trend of increasing. The density on study routes was 0.9 pairs/100 km2. We project 150-196 pairs to breed in the all steppe depressions of the Irkutsk district. The highest number of the Upland Buzzard was registered in the Borgoyskaya steppe in the Republic of Buryatia, where about 31% of the total number projected for the Republic breed. The density was 2.93 pairs/100 km2, and the average distance between nests was 5.58±3.65 km (n=21; 2.27 14.98 km). A total of 395-495 pairs are estimated to live in the all steppe depressions of the Republic of Buryatia. Successful breeding was registered for 55.6% nests (n=9) in the Irkutsk district. Visited 4 active nests contained broods with 4 chicks each. Also successful breeding was recorded for 92.7% nests (n=41) in Buryatia. The average brood size was 2.33±1.12 fledglings per successful nest (range 1-4) with prevailing the broods with 1 (30.0%) and 2 (26.7%) chicks. The most part (95.92%) of 48 nests found in the region was located on trees. Two nests were found on rocks located in mountain-steppe landscapes of the central part of steppe depressions in Buryatia. The most number of nests (46.8%) was built up on pine trees, rarely buzzards use to build their nests on larches (38.3%) and elm trees (10.6%), and more seldom another species of trees. A lot of nests (63.8%) were in a branches fork of in the base of branches of the upper third part of tree with obvious preferring the branch forks for nesting (46.8%). The high of nest location(n=48) varied widely from 1.5 to 22 m, averaged 8.52±4.84 m. Saker Falcon (Falco cherrug) During our surveys we found 23 breeding territories of the Saker Flacon, 15 from which on study areas (Fig. 13-1). The species was noted breeding in the Balagano-Nukutskaya forest-steppe in the Irkutsk district, where we found 4 breeding territories, single birds were recorded in the Kuda river valley and near an old nest in the Olchon river region. Now valuable breeding population of the species exists only in the Balagano-Nukutskaya forest-steppe. The average distance between nests of different pairs was 15.71±4.16 km (n=3; 11.9-20.2 km), density 0.42 pair/100 km2. A total of 50-65 pairs to breed in the Balagano-Nukutskaya forest-steppe, and we project 42-52 pairs living on the all territory of the Irkutsk district. The number of the species seems to decrease in about 2 times during last 10 years. The Saker Falcon is a common breeding species in the Borgoysaya steppe in Buryatia. We found 8 breeding territories (7 in the study area) on 11-14 July, the average distance between territories was 10.89±2.86 km( n=8; 7.6-17.4 km), the density was 1.28 pairs/100 km2. Also we found sakers breeding in the Selenga river valley, Tugnuyskaya, Chilokskaya and Ivolginskaya depressions (the density was pairs/100 km2). A total of 135-165 pairs to live in depressions of Buryatia, 40,5% of which breed in the Borgoyskaya steppe. The number seems to decrease especially around Ulan-Ude, where we found abandoned breeding territories with empty nests. The Saker Falcon is common to nest on trees in the region as a whole: 57.89% of found nests (n=19) were located on trees and 42.11% on rocks. The Saker prefers to build its nests (n=11) on pine trees (54.4%), on larches (36.4%) and elm trees (9.1%). All tree-nested sakers occupied nests of the Upland Buzzard (63.6%) in Buryatia, and nests of the Imperial Eagle (36.4%), which located only on pine trees. The most part (62.5%) of rock-nested sakers (n=8) used to nest niches without any nest constructions and only 37.5% occupied nests of the Upland Buzzard on shelves. The portion of empty nest was 34.78% in the Baikal region,by the way only a half of found nests was successful in the Balagano-Nukutskaya forest-steppe, and meanwhile all found nests were active in the Borgoyskaya steppe. The average brood size was 2.73±1.01 (n=11; 1-4). Also we found 5 nests with carcasses of chicks 1-3 chicks per each, probably the main reason of deaths was insufficient feeding. Peregrine Falcon (Falco peregrinus) An active nest was found on a cliff of the Mara river and an adult bird was recorded on a cliff of the Uda river on 26 June, 2005. An adult bird was observed on cliffs of the Oka river near Zima village, however the nest wasn't found. Another active nest with 3 chicks was found on a cliff of the Buguldeyka river on 5 July, 2005. Also we found the nest leaved by fledglings on a cliff of the Irkut river in the Tunkinskaya depression on 6 July. We observed single adult birds in 2 places with distance 8 km between registrations in the Selenga river valley on 8 July. We project more than 10 pairs breed in the depressions of the Irkutsk district and about 10-15 pairs in the Republic of Buryatia. Eagle Owl (Bubo bubo) We found 14 breeding territories in the Baikal region, active nests were found on 12 territories (Fig. 15). The average size of brood was 1.88±0.83 fledglings (n=11; 1-3). During surveys we found the Eagle Owl breeding in the Kuytun-Ziminskaya and the Balagano-Nukutskaya forest-steppes in the Irkutsk district, also a single adult bird was noted in the Kosaya steppe in the Buguldeyka river valley. The average distance between nests was 9.17±4.82 km (n=6; 3.7-14.3 km), the density was 0.84 pairs/100 km2. We project 90-100 pairs to breed in the Balagano-Nukutskaya forest-steppe and 115-135 pairs in the all steppe depressions of the Irkutsk district. We didn't find the Eagle Owl breeding on the study areas in Buryatia because the reason that areas didn't include cliffs useful for the Eagle Owl nesting. At the same time we noted owls breeding for every visited territories abundant cliff-fraces, in particular in the Irkut river valley in the Tunkinskaya depression, in the Borgoyskaya steppe, in the Selenga river valley and the Gusinoozerskaya depression. The distance between pairs was 10.21 km in the Selenga river valley. A total of 90-110 pairs are estimated to live in Buryatia, about 40% of which were in the Selenga river valley. All found nests were on cliffs, only 22.22% of which (n=9) were located in foot of cliffs, while 88.89% were in niches and only a nest was on an open shelf (fig. 16). Methods In 2005 we have continued the surveys of raptor populations in Siberia which had been started in 1999. In this season a field group of the Field Research Center surveyed the Baikal region (24 June -21 July 2005). The total length of survey routes was 5322 km. We set 4 study areas with a total area of 2125.63 km2 for monitoring the raptor numbers in the Baikal region (table 1, fig. 3). The Baikal region is a large territory in Eastern Siberia near the Baikal Lake. The region includes mountains and steppe depressions in the river valleys. Analysis of satellite images Landsat-7 ETM+ used to create the detailed map of steppe depressions. Different types of steppe depressions have been distinguished with use of landscape criterion and vegetation index (fig. 2). The total area of the steppe depressions in Baikal region is 44027.47 km2 (table 1). The found breeding territories of raptors were GPSed and mapped using GIS software (ArcView 3.2a, ESRI, CA, USA) for the subsequent calculation of the density (Karyakin, 2000, 2004). The study areas include all types of rocks, steppes and forests, which are very character for the surveying territory (fig. 2, 3). A number of species noted to breed in a study area was extrapolated for the total area of the steppe depression with similar landscape and vegetation conditions. Results of studies Golden Eagle (Aquila chrysaetos) We found 9 breeding territories in steppe depressions of the Irkutsk district and the Republic of Buryatia, 8 from which were located on study areas. One active nest of the Golden Eagle located on a pine tree was found on 30 June in the Irkutsk district. A total of 15-20 pairs are estimated to live in the steppe depressions of the Irkutsk district. We found 8 breeding territories in steppe depressions of the Republic of Buryatia (fig. 4), 7 from which were located on study areas. The distance between the nests was 11.4±5.3 km (n=3; 5.4-15.1 km) (M±SD, lim.). The density in the steppe depressions was 0.26 0.73 pair per 100 km2, averaged 0.57 pair per 100 km2. A total of 80-100 pairs are estimated to live in the southern steppe depressions of the Republic of Buryatia (15532.10 km 2). All nests were located on trees: on a pine (5) and a larch (1). The brood size averaged 1,4±0,55 (n=5; 1-2). Imperial Eagle (Aquila heliaca) We found 29 breeding territories and 11 living nests of the Imperial Eagle. Eleven breeding territories were found in the Balagano-Nukutskaya forest-steppe, 10 from which were located on the study area № 1 (fig. 5). The density of the breeding territories of the Imperial Eagle in the Balagano-Nukutskaya forest-steppe was 1.4 per 100 km2. The distance between the nests was 8.05±3.51 km (n=11; 2.51-13.66 km). Only 6 nests from 11 (54,55%) were occupied, and breeding was noted only in 5 nests, and only 4 nests (36,36%) were with chicks. Five breeding territories were identified as abandoned. The density of the active nests of the Imperial Eagle in the Balagano-Nukutskaya forest-steppe was 0.84 per 100 km2. A total of 90-100 pairs are estimated to live in the Balagano-Nukutskaya forest-steppe and 96-112 pairs in the all steppe depressions of the Irkutsk district. The decreasing of raptor numbers is about 40%. Surveyed 6 living nests in the Irkutsk district were with broods included 1-2 chicks, averaged 1.5±0.6 chicks per successful nest (1.13 chicks per an active nest and 0.56 chicks per breeding territory). We found 13 breeding territories in steppe depressions of the Republic of Buryatia, 10 from which were located on study areas (76.9% breeding territories we found in the Ivolga steppe depression). The density in the Ivolga steppe depression was 2.57 pairs per 100 km2. The density of active nests of the Imperial Eagle was 2.05 per 100 km2. The distance between nests was 5.1±1.5 km (n=9; 2.9-7.1 km). Successful breeding was registered only in 46.2% of breeding territories on the Republic of Buryatia. A total of 150-176 pairs are estimated to live in the all steppe depressions of the Republic of Buryatia (82.7% pairs in the Ivolga steppe depression). The average brood (n=4) size was 1.75±0.5 chick per successful nest (0.7 chick per occupied nest and 0.54 chick per surveyed nest). We found 2 broods in 3 nests, 1 fledgling in a nest and 2 active nests were not visited. Recorded nests (n=37) were located on pines (81.08%) on larches (18.92%), by the way all nests noted on larches were noted only in the Baikal region. The nests noted on pines were settled on single trees, in deep forest (about 150 m far from the edge of forest) (13,51% each) and on edges of forest (72.97%). 56,7% nests were built up on a top of pines, 40,0% in a brunch fork under the top of tree, and a nest was in a brunch fork of upper third part of a tree. The nests noted on larches were built up in a brunch fork in the upper third part of a tree (42.9%), in a brunch fork under the top of tree and in the base of branches (28.6% each). Steppe Eagle (Aquila nipalensis) We recorded 3 breeding territories on the study area №1 in the Irkutsk district. A pair of the Steppe Eagle occupied an old nest of the Imperial Eagle and noted near it. Two another pairs were recorded in more typical places for Steppe Eagles on mountains with cliff-faces. We found empty nest in one of territories with signs of previous year breeding. The density was 0.42 pair/100 km2. The distances between the centres of breeding territories were 4.28 and 14.23 km. The all registrations of Steppe Eagles were on the territories, where Imperial Eagles were absent by different reasons. We project 5-10 breeding pairs of the Steppe Eagle for the Irkutsk district. We found 8 breeding territories in the republic of Buryatia, 5 of which were surveyed in study areas. The highest number of Steppe Eagle was noted in the Borgoyskaya steppe, were 62,9% of local population breed. The average distance between breeding pairs was 13.6±1.8 km (n=3; 11.6-14.9 км). We found a dead clutch contained 2 eggs in a nest and broods contained a chick per each in 4 nests. Great Spotted Eagle (Aquila clanga) An adult bird was recorded in wetlands of upper reaches of the Chalyuta river in 6 km to north-west from Ivolginsk on 8 July 2005. White-Tailed Eagle (Haliaeetus albicilla) An adult bird was observed on the right side of the Selenga river near the lower reaches of Itantsa river on 8 July, 2005. Booted Eagle (Hieraaetus pennatus) We surveyed the Booted Eagle in 6 places in the Irkutsk district, 2 of which were identified as breeding territories, 2 as probable breeding territories, and in 4 places in the Republic of Buryatia, the breeding is projected for one territory (fig.7). The distance between breeding territories was 32.5 km in the Balagano-Nukutskaya forest-steppe and 26.5 km in the Tugnuyskaya depression. The density was 0.25 pair/100 km2 (0.14 pair/100 km2 including the study areas, where birds were not recorded). Following the records of auto routes (perpendicular distance was 1 km) the density was 0.19 pair/100 km2. We project 62-83 pairs of the Booted Eagle to breed in the steppe depressions of the Baikal region. Nests of the Booted Eagle recorded in Balagano-Nukutskaya forest-steppe were on larch trees in the isolated forest in 30 and 60 m far from edges. The nest near Elantsy village was built up on a pine tree and located on a slope of the ravine in a segmented forest in 1 km far from a steppe valley. Upland Buzzard (Buteo hemilasius) We found the Upland Buzzard breeding in the Balagano-Nukutskaya forest-steppe, valleys of the Kuda and Selenga rivers, the Ivolginskaya, Tugnuyskaya and Chilokskaya depressions, around the Gusinoe Lake and in the Borgoyskaya steppe. The average density was 1.83 pair/100 km2 (1.12-2.93 pairs/100 km2). The average distance between nests was 5.56±3.83 km (n=45; 1.42-17.36 km). Under optimal conditions without heavy press of eagles Upland Buzzards breed with the distance 3-6 km between pairs. The increasing or decreasing of density in some territories is impacted by limits of suitable places foe nesting and competition with eagles (Fig. 7, 10). The density of the Upland Buzzard is inverse proportional to the density of eagles. The heaviest competition for nesting places is noted with the Imperial Eagle, which connected with preferring these two species similar places for nesting edges of forests. During our surveys 9 breeding territories were found in the Irkutsk district and 43 territories in the Republic of Buryatia. The density of the Upland Buzzard is 1.12 breeding pairs/100 km2 in the Balagano-Nukutskaya forest-steppe, the average distance between nests is 6.69±5.1 km ((n=7; 1.67 15.35 km). A total of 110-140 pairs to live on this territory, and the number has stable trend of increasing. The density on study routes was 0.9 pairs/100 km2. We project 150-196 pairs to breed in the all steppe depressions of the Irkutsk district. The highest number of the Upland Buzzard was registered in the Borgoyskaya steppe in the Republic of Buryatia, where about 31% of the total number projected for the Republic breed. The density was 2.93 pairs/100 km2, and the average distance between nests was 5.58±3.65 km (n=21; 2.27 14.98 km). A total of 395-495 pairs are estimated to live in the all steppe depressions of the Republic of Buryatia. Successful breeding was registered for 55.6% nests (n=9) in the Irkutsk district. Visited 4 active nests contained broods with 4 chicks each. Also successful breeding was recorded for 92.7% nests (n=41) in Buryatia. The average brood size was 2.33±1.12 fledglings per successful nest (range 1-4) with prevailing the broods with 1 (30.0%) and 2 (26.7%) chicks. The most part (95.92%) of 48 nests found in the region was located on trees. Two nests were found on rocks located in mountain-steppe landscapes of the central part of steppe depressions in Buryatia. The most number of nests (46.8%) was built up on pine trees, rarely buzzards use to build their nests on larches (38.3%) and elm trees (10.6%), and more seldom another species of trees. A lot of nests (63.8%) were in a branches fork of in the base of branches of the upper third part of tree with obvious preferring the branch forks for nesting (46.8%). The high of nest location(n=48) varied widely from 1.5 to 22 m, averaged 8.52±4.84 m. Saker Falcon (Falco cherrug) During our surveys we found 23 breeding territories of the Saker Flacon, 15 from which on study areas (Fig. 13-1). The species was noted breeding in the Balagano-Nukutskaya forest-steppe in the Irkutsk district, where we found 4 breeding territories, single birds were recorded in the Kuda river valley and near an old nest in the Olchon river region. Now valuable breeding population of the species exists only in the Balagano-Nukutskaya forest-steppe. The average distance between nests of different pairs was 15.71±4.16 km (n=3; 11.9-20.2 km), density 0.42 pair/100 km2. A total of 50-65 pairs to breed in the Balagano-Nukutskaya forest-steppe, and we project 42-52 pairs living on the all territory of the Irkutsk district. The number of the species seems to decrease in about 2 times during last 10 years. The Saker Falcon is a common breeding species in the Borgoysaya steppe in Buryatia. We found 8 breeding territories (7 in the study area) on 11-14 July, the average distance between territories was 10.89±2.86 km( n=8; 7.6-17.4 km), the density was 1.28 pairs/100 km2. Also we found sakers breeding in the Selenga river valley, Tugnuyskaya, Chilokskaya and Ivolginskaya depressions (the density was pairs/100 km2). A total of 135-165 pairs to live in depressions of Buryatia, 40,5% of which breed in the Borgoyskaya steppe. The number seems to decrease especially around Ulan-Ude, where we found abandoned breeding territories with empty nests. The Saker Falcon is common to nest on trees in the region as a whole: 57.89% of found nests (n=19) were located on trees and 42.11% on rocks. The Saker prefers to build its nests (n=11) on pine trees (54.4%), on larches (36.4%) and elm trees (9.1%). All tree-nested sakers occupied nests of the Upland Buzzard (63.6%) in Buryatia, and nests of the Imperial Eagle (36.4%), which located only on pine trees. The most part (62.5%) of rock-nested sakers (n=8) used to nest niches without any nest constructions and only 37.5% occupied nests of the Upland Buzzard on shelves. The portion of empty nest was 34.78% in the Baikal region,by the way only a half of found nests was successful in the Balagano-Nukutskaya forest-steppe, and meanwhile all found nests were active in the Borgoyskaya steppe. The average brood size was 2.73±1.01 (n=11; 1-4). Also we found 5 nests with carcasses of chicks 1-3 chicks per each, probably the main reason of deaths was insufficient feeding. Peregrine Falcon (Falco peregrinus) An active nest was found on a cliff of the Mara river and an adult bird was recorded on a cliff of the Uda river on 26 June, 2005. An adult bird was observed on cliffs of the Oka river near Zima village, however the nest wasn't found. Another active nest with 3 chicks was found on a cliff of the Buguldeyka river on 5 July, 2005. Also we found the nest leaved by fledglings on a cliff of the Irkut river in the Tunkinskaya depression on 6 July. We observed single adult birds in 2 places with distance 8 km between registrations in the Selenga river valley on 8 July. We project more than 10 pairs breed in the depressions of the Irkutsk district and about 10-15 pairs in the Republic of Buryatia. Eagle Owl (Bubo bubo) We found 14 breeding territories in the Baikal region, active nests were found on 12 territories (Fig. 15). The average size of brood was 1.88±0.83 fledglings (n=11; 1-3). During surveys we found the Eagle Owl breeding in the Kuytun-Ziminskaya and the Balagano-Nukutskaya forest-steppes in the Irkutsk district, also a single adult bird was noted in the Kosaya steppe in the Buguldeyka river valley. The average distance between nests was 9.17±4.82 km (n=6; 3.7-14.3 km), the density was 0.84 pairs/100 km2. We project 90-100 pairs to breed in the Balagano-Nukutskaya forest-steppe and 115-135 pairs in the all steppe depressions of the Irkutsk district. We didn't find the Eagle Owl breeding on the study areas in Buryatia because the reason that areas didn't include cliffs useful for the Eagle Owl nesting. At the same time we noted owls breeding for every visited territories abundant cliff-fraces, in particular in the Irkut river valley in the Tunkinskaya depression, in the Borgoyskaya steppe, in the Selenga river valley and the Gusinoozerskaya depression. The distance between pairs was 10.21 km in the Selenga river valley. A total of 90-110 pairs are estimated to live in Buryatia, about 40% of which were in the Selenga river valley. All found nests were on cliffs, only 22.22% of which (n=9) were located in foot of cliffs, while 88.89% were in niches and only a nest was on an open shelf (fig. 16). |
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