Adam Zbyryt, Dawid Cząstkiewicz, Sebastian Menderski, Marian Szymkiewicz
Ornis Polonica 2018, 59: 171–182
https://doi.org/10.12657/ornis.2018.3.0
Abstract: During the survey conducted in 2017 in the area of 23 661 km2 in Warmia and Mazury (NE Poland) a total of 105 colonies of the Rook Corvus frugilegus, containing 8660 nests, were found. In addition we found 6 breeding sites with 1–2 nests. The mean density of the rookeries was 0.4 colony/100 km2, and the breeding population density was 36.6 nests/100 km2. Mean colony comprised 83.9 nests (SD=113.1). Small rookeries (≤50 nests) constituted 60.0% (N=63), medium (51–100 nests) 10.5%; (N=11), and large (>100 nests) 29.5% (N=31) of all. The 55% of the breeding population (N=61) was located in cities, 18.9% in towns (N=21), 17.1% in villages (N=19), and 9.0% in non-urbanized areas (N=10). No significant difference in the colony size between cities and villages was found. The total number of nest trees equalled 2224, and they represented 23 taxa (species or genus). Deciduous trees constituted 95.4% and conifers 4.6% of all the trees with the Rook nests. The distribution of Rook colonies was similar to that found in 1985–1993 in the same area, but recent data indicate a decline in the size of the breeding population.
Keywords: breeding colony, Corvids, population size, Rook Corvus frugilegus
