Bird diversity along a riparian corridor in a moderate urban landscape

Abstract

Civilization built around rivers directly affects riparian corridor structure and ecology. Degradation, pollution, and deterioration along riparian corridors in urban landscapes change species composition and biodiversity. Birds are one of the most vulnerable taxa to ecological changes. The main objective of our study was to spatially compare bird species richness, abundance, and community structure along the Asar River, an urban riparian corridor in Düzce, Turkey. We identified 63 bird species, comprising 6722 individuals, and classified them into one of three groups: generalist species (11 species), woodland species (40 species), and waterbird species (12 species). Bird species richness was positively related to vegetative cover and negatively to urbanization. Richness was low in the winter and was higher during spring and summer. Riparian Quality Index (RQI) scores (mean = 54.8 ± 33.7; max. = 97 and min. = 5) were relatively low for all sampling plots and was reduced by human activities (e.g., roads, farmland, settlement). The number of woodland bird species changed positively (r = 0.71) with RQI. The generalist bird species, adapted to urbanization, were more common around settlements and open areas. Human population and settlement around Asar River increased one-third and farmland and natural habitat decreased one-fifth during the last decade. The area has high potential for growth and increased urbanization, thus increasing the pressure on the natural areas. Activities that diminish the amount of tree cover in the riparian corridor should be avoided. Habitat restoration and rehabilitation will increase RQI values, which can be used as indicators for bird richness in urban landscapes and benefit avian diversity along the riparian corridor. The existing riparian corridor and any enhancements to the corridor will help conserve Düzce’s biodiversity in the future.