<p>Biodiversity declines in urban environments have frequently been reported, with factors such as tree cover and degree of urbanization affecting community responses in urban landscapes. Some ecological guilds may be more affected by urbanization than others, especially urban avoiders, due to their ecological and morphological traits. We evaluated the effect of tree cover, urbanization (building density), and human population density on bird abundance and species richness (considering all species and different ecological guilds) in the city of Campo Grande, Mato Grosso do Sul, Brazil. We also evaluated which beta-diversity process (nestedness or turnover) explains most of the variation in community composition. We recorded 2,140 individuals of 89 bird species. For forest species richness and abundance, we found a positive effect of tree cover. On the other hand, we found a negative effect of tree cover on abundance for human-modified habitat species, granivore species, and terrestrial species. Beta-diversity was mainly caused by species turnover rather than by nestedness, with turnover being explained primarily by tree cover and human population density. Overall, our results showed that tree cover is important in determining bird assemblage composition in urban environments.</p>