Adam Zbyryt, Małgorzata Zbyryt, Paweł Siwak, Zbigniew Kasprzykowski
Ornis Polonica 2013, 54: 25–39
https://doi.org/10.12657/ornis.2013.1.2
Abstract: The research was conducted in 2012 within the area of 20187 km². The total numbers of rookeries were 134 with 10666 nests. The mean density of the population was 52 pairs/100 km² of the total area and 76 pairs/100 km² without forests. It has been shown very large differences in mean densities in the individual districts (7–3309 pairs/100 km²). Colony size reached 83.1 nests on average (SD=137.8). Small colonies (N=79) to 50 nests were 62% of the total number. In the three largest cities (Białystok, Suwałki, Łomża) nested 22% of pairs (N=2329). Most colonies in one city was in Białystok (N=23), whose average size was 25.9 nests (SD=23.2). The nest were built on 2720 trees, 35 taxons (genus or species), including 8 coniferous, mostly on European Ashes Fraxinus excelsior (20.1%), Scots Pines Pinus silvestris (18.1%), Norway Maples Acer platanoides (13.5%) and Canadian Poplars Populus × canadensis (9.9%). Others bird species were found nested in rookeries e.g. Wood Pigeon Columba palumbus, Kestrel Falco tinnunculus and one mixed colony with Grey Heron Ardea cinerea. The main factors that influence of low density of the Rook population in the Podlaskie province are probably changes in agricultural crops.
