VULNERABILITY OF THE ORNITHOFAUNA OF THE LOWER REACHES OF THE SULA RIVER TO THE IMPACT OF NATURAL AND ANTHROPOGENIC FACTORS

Abstract

The avifauna of the lower reaches of the Sula River is vulnerable to the influence of a complex of natural and anthropogenic factors. The study area, which is part of the Nyzhniosulskyi National Nature Park, combines a variety of wetland biotopes that play a key role in maintaining the region's biodiversity. The analysis identified 222 bird species, 24 of which are listed in the Red Book of Ukraine. Between 1991 and 2024, based on data from the Lubny meteorological station, an increase in the average annual temperature (by 0.82 °C per 10 years) and a decrease in precipitation (by 25.6 mm per 10 years) were recorded, indicating a climatic trend towards warming and aridity. Climate change is leading to a shift in migration times, a reduction in nesting areas and a decrease in the food base, especially for wetland species. In particular, the grey heron (Ardea cinerea) and the great egret (Egretta alba) are arriving earlier and departing later, while the great cormorant (Phalacrocorax carbo) tends to remain sedentary during warm winters. The destabilization of the hydrological regime of the lower Sula River, silting of the riverbed and overgrowth of channels lead to the loss of nesting sites for species such as the eurasian coot (Fulica atra) and the greylag goose (Anser anser). Anthropogenic pressure caused by fires, logging, fishing and recreational activities further exacerbates habitat degradation. Burning dry vegetation kills eggs and chicks, while noise and visual disturbances force birds to abandon their nesting sites. Together, natural and anthropogenic factors exert a sustained multifactorial pressure that reduces bird populations and increases the ecological vulnerability of the region's ornithocomplexes.