Arkadiusz Sikora, Przemysław Wylegała, Dawid Cząstkiewicz, Paweł Czechowski, Grzegorz Lorek, Sebastian Menderski, Tomasz Bajdak, Łukasz Ławicki
Ornis Polonica 2026, 67: 1-21
https://doi.org/10.12657/ornis.2026.1.1
Abstract: In northern and western Poland (37% of the country’s area), 26,318 occupied Rook Corvus frugilegus nests were recorded, with a density of 22.4 nests per 100 km². In 2025, 13,481 nests were found in Greater Poland (GP, 37.6/100 km²), 536 nests in Lubusz Land (LL) (4.7/100 km²), and 3,811 nests in Pomerania (PM)(8.3/100 km²), and in 2023 in Warmia and Masuria (WM) 8,490 nests (36.0/100 km2). The Rook was unevenly distributed being the most common in GP and WM, scattered throughout PM and nested only sporadically in the LL. The Rook nested most frequently in cities (80.1% of nests), with 16.6% of its population recorded in villages and 3.3% on water reservoir islands. In the LL, all the nests were located in cities, and in WM, they accounted for 27.7% of all nests. Most of the urban population (68.5%) was recorded in small towns (up to 20,000 inhabitants). Rooks nested most frequently in parks and scattered woodlands (a total of 84.0% of colonies and 83.4% of nests). Most nests of the Rooks were found in trees of the genus Acer sp. (23.9%), Fraxinus spp. (15.8%), Tilia sp. (9.8%), and Quercus sp. (9.7%). Small colonies of up to 50 nests (59.7%) dominated, but 60.8% of nests were concentrated in large colonies (101–400 individuals). In the 21st century, a decline in the number of Rooks in northern and western Poland was recorded, including a 42% decline in northern GP (2012–2025), Leszno Region – 62% (2010–2025), LL – 56% (2004–2025), PM – 46% (2012–2025). A similar trend was observed in WM over the last two decades, but between 2017 and 2023, the population declined slightly, with a clear downward trend in rural colonies. The decline in the population of this endangered species, combined with strong human pressure in the form of destruction of breeding colonies, indicates the need for more restrictive protection of the species and the breeding sites of the Rook in Poland.
Keywords: abundance, density, Greater Poland, Lubusz Land, mesoregion, Pomerania, vulnerable species, Warmia and Masuria
