The influence of habitat types on bird community in urban parks

Abstract

We selected 21 green areas in the City of Puebla and its metropolitan area, located in the central region of México, to explore the relationships between habitat heterogeneity and bird communities in urban environments. For each site, tree vegetation heterogeneity was summarized using 14 floristic and six physical descriptors of habitat structure. During May 2004, bird communities at each site were surveyed by means of the Echantillonnage Frécuentiels Progressifs method (355 censuses, from 10 to 30/site), and their structure was described by the number of species (total species, urban exploiters, urban adapters, and urban avoiders), the Shannon diversity of the assemblages, and the nestedness in species composition. A principal components analysis (PCA) was used to find main axes of variation in tree vegetation descriptors. The first principal component described a gradient in the physical diversity of the tree vegetation; the second component described changes in richness, density, and diversity of the native trees; and the third and fourth described gradients in the diversity and dominance of exotic trees. Although apparent spatial changes in the metrics measuring the structure of bird communities were found in the region, no robust, statistically significant effect of the habitat gradients described by the PCA was found. The relative abundance of seven bird species was correlated to several of the principal component axes, but this relationship was not statistically significant when correcting for multiple comparisons. The structure of bird communities in the urban green-spaces of the City of Puebla and its metropolitan area was not strongly a function of the habitat het-erogeneity measures analyzed, but it may depend on variables acting at different scales, or on a combination of both explanations. Bird communities in Puebla did, however, exhibit a strong pattern of nestedness across sites and reflected similar changes in community composition as found in cities in temperate climates.