Winter avifauna of the forb-feather grass steppe (Kostanay Region, Karabalyk District) based on route surveys (2024-2025)

In the context of climate change and increasing anthropogenic pressure, the study of avian biodiversity is an important tool for ecological monitoring. Despite a long history of ornithological research in the Kostanay Region, primarily focused on the Naursum Nature Reserve, the winter avifauna of steppe areas, including the depressions in the relief, remains poorly studied. The aim of this study is to analyze the species composition and structure of the winter avifauna in depression biotopes (logs) within the forb-feather grass steppe in the Karabalyk District, Kostanay Region. The research was conducted from December to February (winter 2024-2025) in three different biotopes (Toguzakskiy Log, Ovrag Sukhoy, Log Bolshoy) using route surveys based on the methodology of Yu.S. Ravkin (routes ≥5 km, without transect width restrictions). During the observations, significant differences in species structure and dominant avifauna complexes were established between the biotopes, associated with a complex of factors (food resources, nesting sites, etc.). The dominant families included: Calcaridae Ridgway, 1901, with a share of 25%; Paridae Vigors, 1825, – 18%; Phasianidae Horsfield, 1821; Fringillidae Leach, 1820, – each at 11%. The limiting factors influencing the formation of winter avifauna in the studied biotopes are discussed.