Urbanizing the wild: Shifts in bird communities associated to small human settlements

Abstract

Urbanization limits the number and type of species that can colonize urban environments. As habitat change and large abundances of urban exploiter species have been related to changes in urban bird communities, we evaluated shifts in the bird communities in 2 small sized settlements, 1 with exploiter species and one without them. Our results show that bird species richness decreases when an area becomes urbanized, regardless of the presence of urban exploiters. While bird densities were low in the human settlement lacking urban exploiters, they were high in the other settlement due to the numbers of 2 urban exploiter species. Bird community evenness decreased from forests to the human settlement lacking urban exploiters, while decreased importantly in the settlement dominated by urban exploiters. The composition of bird communities was highly similar between forest conditions and the settlement lacking urban exploiters, and highly different to that from the settlement with urban exploiters. Our results thus suggest that when an area becomes urbanized, changes in habitat structure and their subsequent invasion by urban exploiter species generate a significant loss in bird species richness, favoring those species that can inhabit and exploit the new urban condition.