Impervious surface and heterogeneity are opposite drivers to maintain bird richness in a Cerrado city

Assessing the influences of habitat structure on bird richness and functional groups can assist planning and management of urban conservation strategies. Here we analyzed how the urbanization of a city from central-west Brazil (Campo Grande) affects a Cerrado hotspot bird community by focusing on richness of bird feeding groups (frugivore, nectarivore, granivore, omnivore and insectivore). We sampled birds in 61 hexagons (16 ha each one) along an urbanization gradient. For each response variable (richness of bird feeding group) we used five predictor variables: impervious surface, Normalized Difference Vegetation Index (sdNDVI), number of trees, edifices, and houses. To assess the effects of urbanization on bird species richness, we fitted multiple regression models and used Akaike's information criterion for small samples to assess model performance. Impervious surface was the main driver of bird richness. The explanation of most plausible models for each response variable ranged from 20 to 51% of richness variability. Overall richness was negatively affected by impervious surface and positively influenced by number of houses and sdNDVI, a proxy of heterogeneity in our study area. The number of trees did not influence plant specialists and granivores, but the number of houses and sdNdvi did. Insectivore and omnivore richness were only affected by impervious surface. Campo Grande city mimics aspects of the Cerrado heterogeneity, including bird community. Our findings give support to urban planning initiatives that optimize patch dynamics and heterogeneity at multiple spatial scales, as being appropriate for cities within Cerrado landscapes.