Bird diversity in an urban ecosystem: the role of local habitats in understanding the effects of urbanization.

Felipe Zilio

Resumo


Urbanization results in environmental changes that directly affect biotic diversity. Birds are particularly affected by urbanization. Noise levels negatively affect birds’ behavior and social communication, while the presence of green areas promotes bird diversity. Understanding the relationship between fauna and urban features is a key aspect of urban planning. Our goal was to understand how bird species assemblages are related to urban features in an intermediate stage of urbanization (a city in Brazil with 2,470 inhabitants/km²). We used canonical correspondence analysis (CCA) and generalized linear models (GLM) analyses to assess how bird species assemblages are affected by urban features (e.g., noise level, abundance of buildings) as well as habitat features (e.g., vegetation cover). We did not find a clear pattern of urbanization, and urban features apparently had a weak effect on bird species distribution. Bird species distribution was spatially correlated, and we identified three groups: 1) grassland and wetland species; 2) forest species; 3) species tolerant to habitat degradation. Species richness was positively related to the proportion of trees, abundance of people and presence of buildings, and negatively affected by higher levels of noise. The abundance of species decreased as noise levels increased, but the proportion of green areas (open or forest vegetation) had a positive effect. Agreeing with previous research, our study shows that noise levels and vegetation cover seem to be the best predictors of diversity in urban areas. Nevertheless, the presence of particular habitats (wetlands, grasslands, woodlots), patchily distributed in the urban matrix, could buffer the effects of urbanization on birds. These habitats should thus be taken into account in urban planning.



Iheringia Série Zoologia

Museu de Ciências Naturais, Fundação Zoobotânica do Rio Grande do Sul

Rua Dr. Salvador França, 1427, 90690-000 Porto Alegre, RS, Brasil

E-mail: iheringia-zoo@fzb.rs.gov.br