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

Resumen

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.