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Rook Breeding Numbers Fell 42–62% in Several Regions of Northern and Western Poland

Rook perched in a tree in Kraków, Poland
Conservation · Population & status

A 2026 assessment of rook (Corvus frugilegus) breeding colonies documented substantial regional declines across northern and western Poland. Surveys covering an area equivalent to about 37% of the country recorded 26,318 occupied nests. The overall density was 22.4 nests per 100 km², with 13,481 nests counted in Greater Poland in 2025, 536 in Lubusz in 2025, 3,811 in Pomerania in 2025 and 8,490 in Warmia and Masuria in 2023.

Where earlier comparable surveys were available, breeding numbers had fallen markedly. Northern Greater Poland declined by 42% between 2012 and 2025, the Leszno area by 62% between 2010 and 2025, Lubusz by 56% between 2004 and 2025 and Pomerania by 46% between 2012 and 2025. The authors also report a downward trend in Warmia and Masuria, with losses particularly apparent among rural colonies.

Most of the occupied nests were now associated with settlements. Cities contained 80.1% of the nests, villages 16.6% and islands in reservoirs 3.3%. Among the urban nests, 68.5% were in towns with no more than 20,000 inhabitants. Parks and scattered stands of trees were important nesting sites within settlements. Small colonies of up to 50 nests were the most numerous, but 60.8% of all nests were concentrated in large colonies containing 101–400 nests.

The researchers place these changes in the wider context of the rook’s decline in Poland and point to human pressure on colonies, including deliberate destruction of nesting sites. They conclude that the scale of the decline and continuing pressure on breeding colonies support stronger protection for the species and its nesting sites.

Sources and image credit

  1. Sikora, A., Wylegała, P., Cząstkiewicz, D., Czechowski, P., Lorek, G., Menderski, S., Bajdak, T., & Ławicki, Ł. (2026). Decline of the Rook Corvus frugilegus breeding population in northern and western Poland in the context of the species status in the country. Ornis Polonica, 67(1), 1–21. https://doi.org/10.12657/ornis.2026.1.1Primary research article in Ornis Polonica issue 2026-1, published in 2026. Surveys across northern and western Poland recorded 26,318 occupied rook nests. Comparable regional datasets showed declines of 42% in northern Greater Poland, 62% around Leszno, 56% in Lubusz and 46% in Pomerania over differing periods between 2004 and 2025; the authors also report decline in Warmia and Masuria and discuss pressure on breeding colonies.

Image: Jakub Hałun / Wikimedia Commons — wild rook photographed in Kraków, Poland, 25 February 2023; representative species image from Poland, not an individual counted in the 2023–2025 breeding surveys; cropped to 16:9. · CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ · Source

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