Autor:
Chmielewski, Sławomir ; Dombrowski, Andrzej ; Jabłoński, Piotr ; Łukaszewicz, Marcin ; Nicewicz, Łukasz ; Trębicki, Łukasz ; Pagórski, Piotr ; Tabor, Jacek
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Temat i słowa kluczowe:
Rook ; Corvus frugilegus ; Mazovian Lowland ; population size ; population density ; habitat preferences
Abstract:
In 2012-2015 nests of the Rook "Corvus frugilegus" were counted in the Mazovian Lowland area (42,379 km2). A total of 69,442 nests on 693 sites were found. The overall population was estimated at 72,125-76,488 nests. The average rookery size reached 100.2 nests (SD = 192.4). There were five colonies (0.7%) with at least 1,000 nests, 368 (52.4%) small colonies with up to 25 nests, 32 (4.6%) sites with single nests and 103 (14.9%) with up to 3 nests. 83% of all nests were located in rookeries with more than 100 nests (26% of all colonies). ; The rookeries were mostly situated on deciduous trees (82.5%). Colonies in coniferous stands were significantly larger than those in the deciduous tree stands. 98.1% of all rookeries were located in the vicinity of human settlements. Colonies were characterized by unstable numbers of nests (years 2012-2014 vs 2013-2015). However, an analysis of population fluctuations in 75 colonies (about 8,000 nests) showed no directional trend, i.e. a decrease in number of nests in one location was compensated by an increase in another one. ; In large cities with several breeding colonies, populations appeared to be stable despite human disturbance. As the Rook nests in colonies, high densities can be recorded in relatively small areas. Therefore, to compare densities and to evaluate population trends for this species data from areas larger than 10,000 km2 should be considered.
Wydawca:
Zielona Góra: University of Zielona Góra, Faculty of Biological Sciences
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Źródło:
International Studies on Sparrows, vol. 41