Noise level and water distance drive resident and migratory bird species richness within a Neotropical megacity

A large body of evidence indicates that urbanization profoundly affects ecological communities, but the extent to which patterns are generalizable across regions, such as in the Neotropics, remains unclear. We examined responses of migratory and resident birds to human disturbance and habitat attributes in Sao Paulo, Brazil, a tropical megacity in South America. In 2017-2018, we surveyed birds across 31 landscapes distributed across the urban landscape and evaluated competing models that included five non-correlated variables explaining variation in species richness: ambient noise level, distance to water, tree cover, human population size, and impervious surface. We recorded 142 bird species, 128 of which were resident and 14 migratory. Richness of both resident and migratory birds declined with increasing noise level and distance to water, which best explained variation in bird communities among the sampled landscapes. Although resident and migratory birds presented similar response patterns to local and landscape attributes, noise level was the best predictor of migratory species occurrence, whereas distance to water best explained the occurrence of resident species. Our results suggest that, although tree cover is important to biodiversity in urbanized landscapes, proper management of urban water bodies and reduction of noise levels are also essential to maintaining avian diversity within tropical urban areas and suggest novel avenues for future research in tropical urban ecology.