The Hooded Crow Corvus cornix density as a predictor of wetland bird species richness on a large geographical scale in Poland

Both groups prefer lowland water areas surrounded by meadows, where rivers are distributed rather evenly, and where precipitation is relatively high. The greatest differences between these groups appear on areas where farmland mechanization is high. Such areas are used by Hooded Crows, but avoided by wetland birds. Besides, unlike wetland species, Hooded Crows definitely avoids the north of Poland which is covered by large dense forests interspersed with rivers. Therefore, the Hooded Crow reflects wetland species richness only in open lowland habitats, dominated by wet meadows, where the landscape is interspersed with rivers and lakes, and hydrological conditions are repeatable from year to year. The Hooded Crow cannot be used as an indicator of wetland birds on a large area of intensively used farmland or in large deciduous forest interspersed with rivers.