Kivonat:

The Zala chapter of BirdLife Hungary conducted point censuses of breeding birds on reservoir 11 of the Kis-Balaton marshiand from 1994 to 1997. About one-third of the marshland was inundated in autumn 1992, therefore, the data allow an analysis of the elfects of water level increase on passerine bird communities. We clustered all census point results into the following categories: inundated reed, inundated sedge, control reed and control sedge. The only species that responded to inundation with increasing density was the Great Reed Warbler (Acrocephalus arundinaceus), other species declined or did not show an obvious trend. We argue that the conservation of original marshland habitats is necessary at Kis-Balaton, besides the large open waters at reservoir I., to provide suitable habitat for marsh living species.