How does urbanization affect the functional bird groups?

There are many small to medium sized districts that have been settled within the original extension of Brazilian Interior Atlantic Forest. Within the São Paulo state, many of these districts are now composed of highly contrasting urban and agricultural ecosystem. Using the district of Tietê as study case, we investigated the occurrence of functional bird groups in the urban and rural zones in order to evaluate significant differences. To do so, we carried out bird survey in 18 point counts within the urban zone and 28 within the city’s rural zone. Each one was sampled monthly (December/2015 – June/2016) with 12 minutes of sampling and unlimited radius. All species were classified into functional groups according to the following criteria: nesting site, diet type, foraging site, residents or migratory and response to urbanization (urban avoiders, urban users and urban dwellers). Factorial analysis (72.4% of the variance) has grouped 4 different functional groups. Two groups were related only to the urban areas (Mann-Whitney α= 0.05; U= 91, p = 0.0003; U= 150, p= 0.022), which are respectively composed of: birds that nest in cavities, granivores, ground foragers and urban dwellers; aerial foragers. Two other groups were related to both areas (U= 289, p= 0.411; U= 263, p= 0.813) and were composed respectively by: birds that nest and forage in vegetation, resident birds, insectivores, omnivores, urban avoiders and urban users; birds that nest on the ground and forage in the water. These results indicated the functional bird groups that were positively affected by urbanization.