Local abundance and spatial distribution of some migratory birds during post-breeding period

The local abundance and spatial distribution of the short- to medium-distance migratory and daytime stopover passerines (Robin Erithacus rubecula, Blackcap Sylvia atricapilla, Chiffchaff Phylloscopus collybita, Blue tit Parus caeruleus, Great tit P. major) were studied in a West Hungarian stopover ground during post-breeding season. The dispergation index of all migratory bird species revealed clumped distribution both in „smallest annual capture year” (abb. SACY) and the „largest annual capture year” (abb. LACY). According to the PCA the spatial occurrences of Blackcap, Blue tit and Great tit captured in LACY showed significantly higher concentration than of those migrating in SACY. The studied species appeared in all four habitats (bushy, forest, grassland, marsh) of the study stopover area, but their clumped spatial distribution showed habitat preference. The abundance-dependent shift of habitat selection was found only in Great tit, the most of them captured in SACY concentrated in grassland with bushy, while the ones captured in LACY grouped in forest habitat type. Blackcaps were grouped the grassland with bushes habitat type where many Dwarf elder (Sambucus ebulus) bushes were available during autumn migration.