Responses of Urban Bird Assemblages to Land-Sparing and Land-Sharing Development Styles in Two Argentinian Cities

SIMPLE SUMMARY: Urbanization negatively affects biodiversity worldwide. As cities are expected to grow in the future, alternative urban developments which allow the conservation of biodiversity within cities are required. Our main aim was to compare the response of bird assemblages to two alternative urban development styles (land-sparing vs. land-sharing) in two Argentinian cities: Santa Fe and Buenos Aires. Additionally, we assessed the response of bird assemblages to landscape features (the coverage of vegetation and distance to the main rivers) and human activity (represented by pedestrian rate and environmental noise). In Buenos Aires, land-sparing enhanced species richness, whereas land-sharing favored the Shannon diversity and Simpson diversity. The pedestrian traffic was negatively associated with bird diversity. We found that each urban development style supported different bird assemblages during the breeding season. Bird species composition was also related to the surrounding coverage of vegetation. Therefore, our study shows that both urban development styles support different bird assemblages, especially during the breeding season, and indicate the need of reducing pedestrian traffic and increasing the coverage of vegetation to enhance species diversity and composition in both cities. ABSTRACT: Urbanization negatively affects biodiversity worldwide. Consequently, alternative urban development styles are required for an eco-friendlier urbanization process. Thus, two development styles have been suggested: land-sharing (buildings mixed with dispersed green space) and land-sparing (buildings interspersed with large green patches). We assessed differences in species diversity and composition of bird assemblages between both development styles in two Argentinian cities: Santa Fe and Buenos Aires. We surveyed birds in land-sharing and land-sparing areas during the breeding and non-breeding seasons. As a control, we also surveyed birds in areas dominated by impervious surfaces. At a local scale, we also measured the environmental noise and pedestrian traffic. At a landscape scale, we measured the percent vegetation cover surrounding development styles and their distance to the main river. In Buenos Aires, species richness was higher in land-sparing than in land-sharing. However, the Shannon diversity and Simpson diversity were higher in land-sharing. In Santa Fe, both urban development styles supported similar species richness and diversity. Species composition varied between land-sharing and land-sparing in both cities during the breeding season. The pedestrian traffic was negatively associated with species diversity. Therefore, both development styles and strategies to reduce pedestrian traffic should be taken into account to enhance different components of species diversity and composition within the urban matrix.