Effects of area size, heterogeneity, isolation, and disturbances on urban park avifauna in a highly populated tropical city

We assessed bird diversity and nesting activity in 54 urban parks in the core of a highly populated East-Asian tropical city to investigate the effects of area, isolation, habitat heterogeneity, and human disturbances on avifauna. Tree density and heterogeneity were lower while isolation was greater in small than in large or medium-sized parks. Yet, park features were often interrelated, with isolation variables negatively correlated to each other, heterogeneity positively correlated to area, and habitat variables mostly positively correlated with one another but variously to disturbances; whereas pedestrian densities wee positively correlated with green area proportions (ISO3) but negatively with the distances to large green areas (ISO2). Park size played a primary role by positively affecting species richness and numbers of nesting species, thus contributing to higher total and nesting species heterogeneity, and determining the occurrence of a greatest number of species. Pedestrian density, canopy cover, and ground heterogeneity played secondary roles, whereas isolation appeared less influential at the community level. Omnivores, granivores, and aerial insectivores appeared more abundant but were dominated by several common species. Nesting was restricted to even fewer species. While species varied in the occupancy responses to these factors, tree heterogeneity positively affected the nesting of Zosterops japonicus and cavity-nesting birds, and predator density negatively affected those of Lonchura punctulata and Streptopelia doves. Improved urban land use planning and park management incorporating these effects should be implemented to enhance breeding and avoid compositional homogenization for long-term sustainability of urban avian diversity.