Changes in bird species richness through different levels of urbanization: Implications for biodiversity conservation and garden design in Central Brazil

Urban processes lead to species loss. Palmas is a young city under construction; thus, it provides a rare opportunity to analyze changes in bird richness in a developing city. Eighty city blocks, which were classified into five different categories according to different levels of urbanization, were sampled. Bird counting took place during a dry season and a rainy season in four parallel transects in each block. In these blocks, we estimated 20 variables related to woody vegetation, land cover and type of urban use. The estimated bird species richness for the study area was very high (151 species); nevertheless, species reduction occurred as a function of the urbanization processes. Although representing only 11% of the city surface, the not-urbanized blocks showed the highest species richness, which corresponded to 96.3% of the richness estimated in the city. The average species richness for most trophic groups, families, open-field or forest species and resident or migratory species decreased significantly in urbanized blocks. According to a Hierarchical Partitioning analysis the environmental variables that made the greatest positive contribution to the variation in bird species richness in urbanized blocks were the percentage of block area planned for residential use, the density of native trees and the percentage area covered by unpaved roads, whereas the commercial block density, the density of exotic trees and the percentage of block area built had the greatest negative contribution. Based on our results, policies aimed to maintain Cerrado native species in urbanized blocks would contribute to reduce bird species loss.

► We estimate bird species richness in a young city with an ongoing urbanization process.
► First alterations, opening of unpaved roads in native cerrado vegetation, led to richness decrease.
► Species richness will be reduced to half the current values once all projected blocks are urbanized.
► In already urbanized blocks density of native trees had a positive effect on bird species richness.
► Some city regulations could be easily recovered to mitigate bird species loss.