Species richness and composition of bird communities in various field margins of Poland

A study was conducted to determine the occurrence of bird species in relation to 70 field margins of an agricultural landscape in SW Poland. Three types of margins were divided according to the volume of tall vegetation, i.e. herbaceous, shrubby, and tree lined. Fifty breeding bird species were recorded, with a mean density of 33.2 pairs/km. The dominant species were non-threatened and were characteristic of forests or of the field-forest mosaic. Tree lined margins showed the highest abundance and bird species richness. Shrubby margins supported the second highest, while open habitats ranked last. Abundances in ecological guilds were affected by the margin type, the presence of field roads, and especially the presence of ditches in the margin structure. Redundancy Analysis showed clear differences in bird communities between the discernable types of field margins. Species richness increased in the combinations of various margin types. In heterogeneous farmland environmental policy should aim at maintaining various types of field margins at high density in the agricultural landscape.