Habitat selection of migrating Sedge Warblers (Acrocephalus schoenobaenus) and Marsh Warblers (A. palustris) in a South-Hungarian reed swamp

Data from a ringing program in a South Hungarian reed swamp, were used to analyse the horizontal and vertical distribution of the juvenile, adult Sedge Warblers and Marsh Warblers during autumn migration. The horizontal spatial pattern of the juvenile and adult Sedge Warblers showed clumped distribution in the reed bed. One thousand three hundred and twenty-five (35%) juvenile and 203 (27%) adult Sedge Warblers were caught in three internal nets of the first line of mist-nets, which represents only 16% of the nets. These 3 nets are standing in the 30-40 m wide zone near open water. Juvenile Marsh Warblers' distribution was clumped, but there was no significant trend in the number of juveniles along the shore-open water gradient (R2 = 0.07). Adult Marsh Warblers' distribution was random in the reed bed. The vertical spatial distribution of the age classes were 1 significantly clumped for both species. The investigation of food dispersion in a reed bed, the vegetation structure and the interspecific competition among reed warblers is required to better understand the habitat selection of reed warblers.