Distribution, abundance and breeding success of the Common Gull Larus canus in Silesia in 2021–2022

A survey of 24 known breeding sites of CommonGull Larus canus in Silesia was conducted in 2021–2022. There were 36 breeding pairs recorded on 17sites in the first year and, taking account of the threeadditional sites discovered in the following season, the abundance in 2021 was assessed at 39–42 pairs.In 2022 Common Gull bred on 18 sites, numbering27 pairs. Abundance on particular sites rangedfrom 1 to 7 pairs. Breeding sites were localized inexhausted gravelpits, sandpits and quarries (42%),dam reservoirs (21%), working sandpits and gravelpits(17%), ponds (12%) and sedimentation basins(8%). Nests were built on islands in gravel pits, sandpits or quarries (52%), logs and branches stickingout of water (35%), man-made structures (10%)and on a sandy shore of a sand pit (3%). The breedingsuccess amounted to 0.38 young per breedingpair in 2021 and 0.1 in 2022. The Silesian breedingpopulation of the Common Gull constituted 7–8%of its national population in the study period. Thespecies colonized the region permanently in 1981and its abundance grew to a record of 70–80 pairsby the end of the 20th century. The trend reversed inthe first decade of the 21st century and the numbersdropped rapidly (by ca. 50–75%), particularly onthe so far most abundantly inhabited gravel pits andreservoirs in Nysa Kłodzka valley. A further, albeitslow, decrease of the Silesian population continuesto this day.