Aims: Urbanization can cause the disorganization of local biotas, especially in tropical, biodiversity-rich latitudes, although some native species can continue inhabiting urban green areas. The main purpose of this paper was to advance into the knowledge of the ecological features that allow those species to survive in urban environments and to identify which sets of characters enhance the risk of local extinction.
Location: Puebla-Cholula Conurbation (PCC), in México, a developing country between the Nearctic and Neotropical Regions.
Methods: First, 355 qualitative point counts (Echantillonnage Frecuentiels Progressifs) were performed in 21 green areas of the PCC to determine the regional distribution and local abundance of 51 species. Then, groups of species were formed through multivariate cluster analysis as a function of their similarity in distribution and abundance. Finally, bird species were characterized (body length, body mass, type of diet and migration status) and multivariate clusters were analyzed to look for differences between groups (through Kruskall-Wallis ANOVA), and also with the avifauna from evergreen oak forest communities described in the literature.
Results: Regional distribution of great-tailed grackle, house finch and house sparrow were maximal, since they were found in all the 21 study areas; local abundances of these species, plus those of inca dove and rock dove, were also high (incidence > 50 %). Regional distribution of seven species (like acorn woodpecker, townsend's warbler or rose-breasted grosbeak) was minimal, since they were located in just one site; and six species exhibited very low local abundances (incidence < 5 %). Cluster analysis formed 3 groups. The abovementioned 5 species with the largest distribution and abundance were included in Group #1, typically urban: thus, the most common species, urban exploiters, were mainly granivorous, resident and had a body size larger than all the remaining species. Urban avoiders (Group #3: "rare" species, with a small regional distribution and local abundance) were mainly insectivorous, included resident, wintering and transient species, and had the smallest body size.
Conclusions: Classification analysis formed three groups of species, similar to those described in the literature of developed countries in temperate latitudes. Ecological features of urban exploiters are not the same than those of "rare" species, neither than those of the bird fauna from natural forest communities. If urban growth keeps provoking the conversion of natural forest habitats into urban environments, green urban areas most likely could not maintain viable populations of many of these bird species.
