Micro-Habitat Nest Preferences of the Great Bittern,Botaurus stellaris, on Fishponds in Central-Eastern Poland

Abstract

The nest-site requirements of the great bittern Botaurus stellaris females in relation to habitat availability were studied in 2003–2006 at fish-pond complexes located in the Lublin and Podlasie regions (eastern Poland). The structure of emergent vegetation and water depth were measured and described in 230 control squares and 98 squares with occupied nests. Water depth, vegetation cover, the height and diameter of reed shoots, the number of flowering shoots, the density of old (dry) and new (green) reed shoots were measured. Great bittern females nested in all available types of emergent vegetation and most of the nests were located in reedbeds. Using the logistic regression model it was shown that when choosing the place for nesting the great bitterns preferred reedbeds with a high density of old-reed stems.