Due to recorded declines in grassland bird species, we investigated the populations of three grassland bird species in the agricultural landscape of the Ljubljana Marsh: the Whinchat (Saxicola rubetra), the Tree Pipit (Anthus trivialis), and the Common Whitethroat (Curruca communis), and mapped habitat types in selected squares. Bird surveys were conducted from 1989 to 1996 and again from 2020 to 2021 in 41 squares, each with a side length of 1 km. Habitat types were mapped in four squares in 2024 and compared with the mappings from 1999 and 2007. The results show a significant population decline: the Whinchat population decreased by 64%, the population of Tree Pipit by 51%, and the Common Whitethroat by 15%. The population decline is most likely associated with the disappearance of extensive grassland habitat types, such as oligotrophic wet meadows, and the increase in the extent of intensive meadows, arable fields, and pastures, which are unsuitable for ground-nesting birds. The most significant declines in breeding pairs were recorded in areas where the area of optimal habitat significantly decreased. An example is the square near Bevke, where 17.5 ha of optimal habitat disappeared due to the expansion of pastures, blueberry plantations, and shrub encroachment, leading to a 47 % decline in the Whinchat population and a 50 % decline in the Tree Pipit population. The pronounced population declines highlight the need to preserve extensive grasslands to protect grassland birds.
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