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Wetlands are naturally patchy habitat types that in fragmented landscapes are usually immersed inside a sea of anthropogenic habitat matrix. Decrease in patch size area and increase of patch isolation are two important components of wetland fragmentation. We investigated the effects of fragment area on bird species richness at four-level assemblages in a highly fragmented Mediterranean wetland system of Central Italy. Our results indicate that fragment area influenced differently the species richness for distinct assemblages in wetland fragments. Area was significantly correlated to total species richness, vagrant, breeding and Phragmites -related breeding species (PBS). A comparison of the various regression equations showed that the log-log relationship was the best-fitted model and the amount of variation ( R 2 of log-log regression line) was much higher for PBS and breeders than for vagrants. This pattern confirmed that when including vagrants in studies based on the equilibrium theory of island biogeography, the ‘insularity of islands’ is reduced. We also found that higher z-values (regression slope) were associated with PBS and breeding birds, supporting the idea of a ‘matrix effect’ on the studied species.

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documentation of Bratislava forest park, with perspectives of management until 2000). Gilbert , F. S. 1980 . The equilibrium theory of island biogeography: fact or

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