Andrzej Dombrowski, Przemysław Stolarz, Artur Goławski
Ornis Polonica 2025, 66: 278–290
https://doi.org/10.12657/ornis.2025.4.2
Abstract: Studies conducted at 12 complexes of fish ponds in the central part of the Południowopodlaska Lowland (E Poland) between 1966 and 2025 enabled an assessment of long-term trends in the abundance of waterbirds. During the analysed period, 44 breeding species were recorded, of which 45.5% showed a decline in abundance, 20.5% an increase, and 27.3% remained stable, while for 6.7% the trend was undetermined. The strongest declines were recorded mainly among Anseriformes (including diving ducks – Common Pochard Aythya ferina and Tufted Duck A. fuligula), as well as the almost all the wader species. Ferruginous Duck Aythya nyroca, Black-necked Grebe Podiceps nigricollis and Black-tailed Godwit Limosa limosa ceased breeding. The Common Crane Grus grus was a newly breeding species. The greatest increases in abundance were observed in large and expansive species, including Whooper Swan Cygnus cygnus, Greylag Goose Anser anser, Common Goldeneye Bucephala clangula, also Bearded Reedling Panurus biarmicus. At the same time, a large group of species, including Mute Swan C. olor, Mallard Anas platyrhynchos, Great Crested Grebe P. cristatus, Euasian Bittern Botaurus stellaris and Common Tern Sterna hirundo, was characterised by stable abundance. The main causes of the observed declines include intensification of fish farming practices, removal of reedbeds and fluctuations in water level, predation pressure from mammalian predators, and habitat degradation. In turn, the increase in the abundance of most species was mainly due to a nationwide trend. This study highlights the need to implement targeted conservation measures aimed at maintaining the diversity of fish pond avifauna, including reducing predator pressure and improving habitat conditions for threatened species.
Keywords: long-term population trends, Południowopodlaska Lowland, waterbirds
