Andrzej Wuczyński
Ornis Polonica 2025, 66: 61-101
https://doi.org/10.12657/ornis.2025.2.1
Abstract: The ornithological value of Poland’s agricultural landscapes is notable in the European context and has recently become the subject of intensified research. Nevertheless, regional data on species richness and bird abundance and their spatial and temporal dynamics remain insufficient. This study presents a synthesis of long-term field research conducted in south-western Poland, covering key components of agricultural habitats: arable fields, linear habitat features (field margins), and patchy woodlots. Aggregated data on species richness and bird abundance were derived from representative sample areas: 12 landscape plots (totaling 600 ha), 70 field margins (35 km), and 20 isolated woodlots (17.5 ha). Most data pertain to breeding birds, whereas on landscape plots (300 ha), wintering birds were also surveyed. The data come from several research projects conducted between 1989 and 2022. Surveys in field margins and woodlots were repeated after 15 and 29 years, respectively, enabling a comparative analysis of long-term changes in avifauna. In the studied agroecosystems, a total of 91 bird species were recorded – 74 during the breeding season and 56 in winter. Species richness was comparable across habitat-rich landscape plots (49 species), woodlots (57), and field margins (55), and clearly higher than in open, large- and small-scale arable fields (13 and 10 species, respectively). The dominant species in landscape plots was the Skylark Alauda arvensis, with a mean density of 7.2 breeding pairs/10 ha. In field margins, the most abundant species included the Marsh Warbler Acrocephalus palustris, Yellowhammer Emberiza citrinella, and Red-backed Shrike Lanius collurio, whereas in woodlots they were the Blackcap Sylvia atricapilla, Yellowhammer, and Chaffinch Fringilla coelebs. Bird densities varied markedly between habitats, reaching 221 and 271 pairs/10 ha in woodlots and field margins, respectively – several times higher than on landscape plots, where they reached 13–24 pairs/10 ha. In winter, the dominant species were the Yellowhammer and Tree Sparrow Passer montanus, together accounting for 51% of all recorded individuals. A total of 11,370 individuals were recorded, translating to a high mean winter density of 356.6 ind./km². Pronounced intra- and interseasonal fluctuations in total and species-specific abundance were observed. Field margins were identified as the preferred wintering habitat. Compared to other regions of Poland, species richness of breeding and wintering birds was similar, but bird densities in south-western Poland were generally higher. Long-term comparisons revealed significant changes in bird abundance in both field margins and woodlots. Over a 15-year period, the number of breeding pairs in field margins declined by 17.7%, while species richness remained stable. The most marked declines were observed in dominant species: Marsh Warbler populations decreased by c. 50%, and Yellowhammer by 20%. In contrast, total bird numbers in woodlots remained remarkably stable over a 29-year period, despite substantial turnover in species composition. In both habitats, species that increased in abundance were primarily woodland birds, whereas characteristic farmland species showed declining trends. The presented data demonstrate that the agricultural landscapes of south-western Poland support rich and abundant bird communities. The findings highlight the crucial role of habitat heterogeneity in maintaining avian diversity and abundance. This study fills a regional knowledge gap on farmland bird populations in Poland and provides a valuable, synthesized dataset for further comparative and conservation-related research.
