Urbanization and bird communities: Spatial and temporal patterns emerging from southern South America

Abstract

Urbanization is an expanding process worldwide, and South America seems to follow the general pattern observed in more urbanized regions of the world. Most conceptual models on the response of biodiversity to urbanization, however, are based on the experience in developed economies. In this chapter, we summarize patterns of bird communities found at different spatial and temporal scales in southern South America. Along a 1,400-km latitudinal gradient we found that urbanization: 1) obscured the latitudinal pattern of bird species richness, 2) had a stronger negative effect on bird richness in tropical than in temperate or arid regions, and 3) resulted in more similar communities than the seminatural or rural areas, suggesting a process of biotic homogenization. The analysis of urban centers of different sizes indicated that bird richness and abundance were negatively affected by urbanization only in cities above 7,000 and 13,000 inhabitants, respectively. In the Pampean region, urbanization affected negatively birds that nest on the ground, with insectivorous and carnivorous diets, feeding on the air and on vegetation and with solitary and migratory behaviors. Urbanization decreased the seasonal and interannual variability of bird species composition. We suggest future directions of research on the influence of latitude on temporal dynamics of bird communities in urban areas, comparison of bird responses to urbanization among biogeographical regions using a mechanistic approach, and including functional and phylogenetic diversity as response variables in the analyses.