Arkadiusz Sikora, Mateusz Gutowski, Damian Ostrowski, Urban Bagiński, Małgorzata Bagińska, Grażyna Jaszewska, Michał Przystański, Michał Barcz, Miłosz Kowalewski
Ornis Polonica 2023, 64: 81–106
https://doi.org/10.12657/ornis.2023.2.1
Abstract: In the 21st century, an increase in the breeding population and territorial expansion of the Pygmy Owl Glaucidium passerinum in Pomerania has been recorded. In the late 1990s, the first territorial male was recorded, and since 2006 the species has been recorded annually. In years 2016–2022, its occurrence was revealed in 15.8% of squares (N=80) out of 507 10 × 10 km plots in the region, being the most common in the central part of Pomerania (30.6% of squares with the species present; N=144), followed by Gdansk Pomerania (14.0%; N=164) and the least numerous in the western part (6.5%; N=199). The Pygmy Owl was most abundant in the lake districts in the southern part of the region, and the population in Pomerania was estimated at 250–350 territories. The most important Pygmy Owl refuges in the region are the Człuchów Forests (50–60 territories), SPA Forest at Gwda River (40–50 territories, including 20–25 territories in the Pomeranian Ornithological Region), SPA Tuchola Forest and Forest at Drawa River (15–25 territories each), and SPA Słupia Valley and Wielki Sandr Brdy (15–20 territories each). In years 2020–2022, the average density in the 9 plots was 1.7 ter./10 km2 of total area (range 0.4–3.0) and 1.9 ter./10 km2 of forest area (0.4–3.2). Of the 71 breeding Pygmy Owl hollows in the Pomerania, the majority were detected in fresh mixed coniferous forest (31.0%) and mixed swamp coniferous forest (26.7%). In the most important refuge – Człuchów Forests – the Pygmy Owls most often inhabited forests with strong humidity (64.3%). Nesting hollows were located mainly in Scots pines Pinus sylvestris (63.0%) and European spruces Picea abies (20.5%) and less abundantly in oaks Quercus sp., birches Betula sp. and alders Alnus sp. Hollows in living trees predominated (76.7%), less frequently in dead (13.7%) and dying trees (9.6%). Scots pine was by far the most dominant species (84.5%) in the Pygmy Owl’s breeding habitat. European spruce was important as a co-dominant species (46.5% of breeding sites), and was present in the undergrowth in 78.9% of the sites. In Pomerania, Pygmy Owls nested in forest divisions where the age of stands ranged from 59 to 199 years (mean 120 years; N=71), with a clear preference for older age classes. Based on the latest data provided in this publication, the Pygmy Owl population in Poland was estimated at 1,900–2,600 territories. The Pygmy Owl population in Człuchów Forests constitutes approx. 2.4% of the national population, in SPA Forest at Gwda River there is 2.0% of the national population, in SPA Tuchola Forest and Forest at Drawa River, in SPA Słupia Valley and SPA Wielki Sandr Brdy there is 0.9% each. The Człuchów Forests area is currently the most important Pygmy Owl refuge in Pomerania and for that reason, it qualifies as a national IBA refuge and a Natura 2000 SPA.
Keywords: distribution, Glaucidium passerinum, habitat, IBA, increase of abundance, Natura 2000 SPA, Pomerania, protection, Pygmy Owl
