Organization and differentiation of breeding bird communities across a forested to urban landscape

As rates of urbanization are increasing, knowledge of the ecology of bird communities and how they vary in transition zones between natural and urban areas would provide critical data to help enhance bird diversity. The organization and differentiation of breeding bird communities were studied in the peri-urban forest, forest ecotone and urban greenspaces of a small coastal Mediterranean city (Kavala, Greece). A total of 49 species, 12 threatened within Europe, were observed; 32 in urban greenspaces, 42 in the ecotone and 39 in the peri-urban forest. Overall abundance was higher and evenness lower in the city than the ecotone and the forest. Species richness was lower in the city than the ecotone. Ordination indicated significant differentiation among communities, with similarity being higher between the forest and the ecotone and lower between the city and the forest. Indicator species analysis determined 14 indicator species; 5 of urban greenspaces (urban dwellers), 1 of the forest ecotone (urban avoider), 1 of the peri-urban forest (avoider), 2 of the city and the ecotone (dwellers/ utilizers) and 5 of the forest and the ecotone (avoiders). Urban dwellers accounted for 68% of the total abundance of urban greenspaces, however homogenization was counterbalanced by the influx of forest species (urban utilizers). Results revealed the diversity, structure and important associations of urban and peri-urban bird communities. Urban plans should incorporate measures to provide suitable breeding habitat to both threatened urban dwellers and forest species to enhance their populations, thus increasing biodiversity and promoting the well-being of urban residents.