Размещение местообитаний ястреба-тетеревятника в растительном покрове Керженского заповедника, россия

• Main Author: Новикова, Л.
• Format: Text
• Language: unknown
• Published: Общество с ограниченной ответственностью «Сибэкоцентр» 2008
• Subjects: ХИЩНЫЕ ПТИЦЫ; ПЕРНАТЫЕ ХИЩНИКИ; ТЕТЕРЕВЯТНИК; Ivlev; Accipiter gentilis
• Online Access: http://cyberleninka.ru/article/n/razmeschenie-mestoobitaniy-yastreba-teterevyatnika-v-rastitelnom-pokrove-kerzhenskogo-zapovednika-rossiya; http://cyberleninka.ru/article_covers/14875203.png

The aim of the work is to describe the distribution of the Goshawk (Accipiter gentilis) habitats in the Kerzhenskiy Reserve at three spatial levels: level of landscapes (breeding territories), level of plants communities (nesting sites) and level of organisms (nesting trees). The State Biosphere Nature Reserve «Kerzhenskiy» is located in the northern half of the Nizhniy Novgorod district. Pine forests prevail in the territory, most of them being young as a consequence of a large forest fire in 1972, which affected up to 90% of the area of the Kerzhenskiy Reserve (Averina, 2001). Methods In June 2008, an examination and description of 27 nests of Goshawk were carried out by a method developed by M.S.Romanov (2001b, 2005). 14 parameters were analyzed: for breeding territories, their location in the landscape; for nesting sites, age of forests, habitat and spatial structure of forest communities; for nesting trees, tree species, size and age, and also location of the nest in the tree. Processing of the data was carried out by a method of the same author (Romanov, 2001b, 2005). Results The Goshawk is a common breeding raptor species in the Kerzhenskiy Reserve. In the territory of the Reserve 27 nests of the Goshawk are known, located in 17 breeding territories (fig. 1). Study of the location of Goshawk nests (n=27) in the landscape reveals a high degree of preference for flood lands. The Ivlev-Jacobs index of selectivity was 0.8 (63% of nests located on flood land and portion of flood lands from the total area of the Reserve being 14%). We assume that it can be explained by a higher growth rate of trees in flood lands in the conditions of the Kerzhenskiy Reserve, which enables birds to choose trees of necessary parameters. The analysis of habitat structure of nesting sites (fig. 2) shows obvious preference of alder and spruce forests (indexes of selectivity are close to one: 0.86 and 0.89, respectively). Birch forests are used proportionally to their abundance (index of selectivity close to zero). This can probably be explained by their age (84.7% of birch forests are 36 years or less). A high degree of avoidance of pine forests was noted (the index of selectivity -0.73), although a significant portion of nests is located in them (about 30% of nests). Also in this case the avoidance can be explained by the age of forests; pine forests are generally formed by young trees (82.4%). The most preferred age intervals of forests for the Goshawk nesting sites are 50 to 80 years (fig. 4). For ages more than 80 years some degree of avoiding was observed. This may be explained by the fact that forests of more than 80 years are generally located on oligotrophic and mesotrophic swamps. As regards the choice of trees for nesting, the greatest preference was observed for spruce (the index of selectivity 0.97) (fig. 6). Pine was also frequently used (37% of nests, the index of selectivity 0.65). The degree of selectivity was also high for aspen (0.75) and alder (0.53). This can possibly be explained by the high growth speed of these species. 15 nests were located on middle-aged trees (57.7%) and 11 nests on old trees (42.3%). The Goshawk avoids middle-age trees when old trees are available (Ivlev-Jacobs index for middle-age trees 0.83). Median of the height of nesting trees in the Kerzhenskiy Reserve (n=26) was 17 m (25% 15 m, 75% 18 m). The mean height of the nest location on a tree (n=25) was 10±2.7 m. The mean diameter of the trunk of nesting trees (n=26) was 37±7.64 cm. The Goshawk prefers trees with diameters of more than 35 cm (fig. 10). The mean diameter of nesting trees (37 cm) is low on the preferred interval; it testifies that in the conditions of the Kerzhenskiy Reserve this species experiences a lack of optimum diameter of trees. Most likely, the Goshawk experiences also a lack of high-capacity trees, as the mean capacity of nesting trees equals 2.21 but most preferred interval is from 2.4 to 3.3 (fig. 11). As regards nests located in the crown (n=26), those placed under a crown were most common (11 nests). 9 nests were found in the bottom part and 6 nests in the middle part of a crown (fig. 12). Conclusions The Goshawk, being a flexible species in its preferences, is able to find suitable conditions at the present stage of development of the plants communities of the Kerzhenskiy Reserve. However, these conditions are not optimal and the species experiences a lack of old-age forest communities and of trees of greater size. This possibly explains the Goshawk's preference of habitats in flood lands. Acknowledgments The author would like to thank I.V. Karyakin, the director of the Centre of Field Studies (N.Novgorod) and A.V. Konstantinov, the senior researcher of the Kerzhenskiy Reserve for valuable advice on processing and representing the data. The aim of the work is to describe the distribution of the Goshawk (Accipiter gentilis) habitats in the Kerzhenskiy Reserve at three spatial levels: level of landscapes (breeding territories), level of plants communities (nesting sites) and level of organisms (nesting trees). The State Biosphere Nature Reserve «Kerzhenskiy» is located in the northern half of the Nizhniy Novgorod district. Pine forests prevail in the territory, most of them being young as a consequence of a large forest fire in 1972, which affected up to 90% of the area of the Kerzhenskiy Reserve (Averina, 2001). Methods In June 2008, an examination and description of 27 nests of Goshawk were carried out by a method developed by M.S.Romanov (2001b, 2005). 14 parameters were analyzed: for breeding territories, their location in the landscape; for nesting sites, age of forests, habitat and spatial structure of forest communities; for nesting trees, tree species, size and age, and also location of the nest in the tree. Processing of the data was carried out by a method of the same author (Romanov, 2001b, 2005). Results The Goshawk is a common breeding raptor species in the Kerzhenskiy Reserve. In the territory of the Reserve 27 nests of the Goshawk are known, located in 17 breeding territories (fig. 1). Study of the location of Goshawk nests (n=27) in the landscape reveals a high degree of preference for flood lands. The Ivlev-Jacobs index of selectivity was 0.8 (63% of nests located on flood land and portion of flood lands from the total area of the Reserve being 14%). We assume that it can be explained by a higher growth rate of trees in flood lands in the conditions of the Kerzhenskiy Reserve, which enables birds to choose trees of necessary parameters. The analysis of habitat structure of nesting sites (fig. 2) shows obvious preference of alder and spruce forests (indexes of selectivity are close to one: 0.86 and 0.89, respectively). Birch forests are used proportionally to their abundance (index of selectivity close to zero). This can probably be explained by their age (84.7% of birch forests are 36 years or less). A high degree of avoidance of pine forests was noted (the index of selectivity -0.73), although a significant portion of nests is located in them (about 30% of nests). Also in this case the avoidance can be explained by the age of forests; pine forests are generally formed by young trees (82.4%). The most preferred age intervals of forests for the Goshawk nesting sites are 50 to 80 years (fig. 4). For ages more than 80 years some degree of avoiding was observed. This may be explained by the fact that forests of more than 80 years are generally located on oligotrophic and mesotrophic swamps. As regards the choice of trees for nesting, the greatest preference was observed for spruce (the index of selectivity 0.97) (fig. 6). Pine was also frequently used (37% of nests, the index of selectivity 0.65). The degree of selectivity was also high for aspen (0.75) and alder (0.53). This can possibly be explained by the high growth speed of these species. 15 nests were located on middle-aged trees (57.7%) and 11 nests on old trees (42.3%). The Goshawk avoids middle-age trees when old trees are available (Ivlev-Jacobs index for middle-age trees 0.83). Median of the height of nesting trees in the Kerzhenskiy Reserve (n=26) was 17 m (25% 15 m, 75% 18 m). The mean height of the nest location on a tree (n=25) was 10±2.7 m. The mean diameter of the trunk of nesting trees (n=26) was 37±7.64 cm. The Goshawk prefers trees with diameters of more than 35 cm (fig. 10). The mean diameter of nesting trees (37 cm) is low on the preferred interval; it testifies that in the conditions of the Kerzhenskiy Reserve this species experiences a lack of optimum diameter of trees. Most likely, the Goshawk experiences also a lack of high-capacity trees, as the mean capacity of nesting trees equals 2.21 but most preferred interval is from 2.4 to 3.3 (fig. 11). As regards nests located in the crown (n=26), those placed under a crown were most common (11 nests). 9 nests were found in the bottom part and 6 nests in the middle part of a crown (fig. 12). Conclusions The Goshawk, being a flexible species in its preferences, is able to find suitable conditions at the present stage of development of the plants communities of the Kerzhenskiy Reserve. However, these conditions are not optimal and the species experiences a lack of old-age forest communities and of trees of greater size. This possibly explains the Goshawk's preference of habitats in flood lands. Acknowledgments The author would like to thank I.V. Karyakin, the director of the Centre of Field Studies (N.Novgorod) and A.V. Konstantinov, the senior researcher of the Kerzhenskiy Reserve for valuable advice on processing and representing the data.