“…Immigration, one of the processes in the island biogeography equation, is well documented in Crimean avifauna (Prokopenko et al 2012, Tsvelykh & Kucherenko 2020), including aquatic species (Vergeles et al 2012, Kucherenko et al 2015, 2017b, 2018); however, such studies tend to concentrate on nesting species. Nevertheless, all phenological periods are important for monitoring bird activity, and data from all seasons are required to fully assess the significance of a locality for bird maintenance during winter (Kwieciński et al 2016, Morelli et al 2018). Data on the diversity of waterbirds in isolated reservoirs, especially in winter, are relatively rare in the literature, and studies of waterbirds tend to be more common from Ramsar wetlands and other hotspots than small ponds.…”