Red clay roof and NDVI drive changes in bird species composition and functional evenness in housing areas of São Paulo megacity, Brazil

Abstract


 
 
 Urbanization creates the most irreversible and human-dominated form of land use, often resulting in species losses and functional homogenization of bird communities. Here we investigate how housing areas in a Neotropical megacity may drive bird species occurrence and functional diversity in high densely habited areas. Using three local scales (radius of 50, 100, and 200 m), we tested how bird species richness, functional groups, and functional diversity indices may be affected by the normalized difference vegetation index (NDVI, a proxy for primary productivity) and the cover area (m2) of red clay roofs (RCR, likely urban nesting sites) in São Paulo megacity, Brazil. We recorded 40 bird species, mostly nesting on trees. Few and high abundant (native and exotic) birds may use roofs and other urban structures as nesting sites. The GLM models showed that functional evenness increased with synchronized increases of NDVI 200 m and RCR 200 m covers and decreased with increase of NDVI 50 m. Most of the bird indices were not affected by neither NDVI nor RCR at local scales. However, bird species composition and functional evenness were sensitive to NDVI and RCR. Our findings suggest that synchronized high values of NDVI (vegetation-linked resources) and RCR cover (likelihood of nesting) may improve the regularity of bird functional traits and ecosystem functions (e.g., frugivory and insectivory) in housing areas of a Neotropical megacity.