Landscape and patch characteristics affecting the assemblages of birds in reedbeds in terrestrial matrix

We conducted an analysis of relationships between results of survey on breeding community of birds, including species richness, abundance of individual species and ecological groups of birds, and habitat features of 91 isolated reed patches in southwestern Poland. The approach to the reedbed habitat involves environmental differentiation at the patch level, landscape context and isolation, including the impact of man-made structures as potential constraints to the occurrence of birds. Generalized linear models have shown that 12 out of 14 analyzed environmental predictors had a statistically significant effect on birds. The results from individual species (sedge warbler, great reed warbler, bluethroat, Savi's warbler, water rail, moorhen and coot) models revealed that the number of territories was affected from two to four predictors. The number of reedbed specialists was affected positively by reed edge, water area and proportion of reed habitat within a 100-m radius, and negatively by railway. The number of water birds was affected positively by reedbed area, internal reed edge, treebelt, distance to reedbed > 1 ha and a proportion of reed habitat within a 100-m radius, and negatively by external reed edge. The proportion of reed habitat within a 100-m radius and internal reed edge were the predictors which positively affected richness of bird species. Our results showed that, apart from the habitat features measured within a reedbed, i.e. area of a reed patch, length of external edge or presence of trees, some other factors measured in larger landscape context, i.e. isolation (expressed mainly as the proportion of reed habitat within a 100-m radius) and the presence of man-made structures are important predictors in explaining the abundance of birds. The area sensitivity of birds nesting in reedbeds in terrestrial habitat was considerably lower than in reed islands located in lakes and wetlands of southern Europe.