Estimating the impacts of habitat loss induced by urbanization on bird local extinctions

Habitat loss and fragmentation can be long-term processes driving extinction debts, especially in cities. Because of a lack of temporal data, long-term impacts are generally investigated less frequently than short-term impacts. However, these effects are equally important for understanding biodiversity loss. We developed a Bayesian Island Biogeography model combining historical imagery and current species distribution to investigate the long-term impacts of urbanization-induced habitat loss and isolation on birds. We surveyed 101 bird species in 43 urban forest patches in a South American city with different combinations of size, isolation, and time since the last abrupt change in area. Based on the current and historical landscape configuration, we estimated the temporal dynamics between species extinction rate and area, and between immigration rate and isolation. Additionally, we used model parameters to forecast bird extinction debts. Large patches had lower extinction rates than small patches, and immigration rates were lower in more isolated patches. Furthermore, current bird species richness was better explained by current landscape configuration than by past configuration, suggesting that birds rapidly respond to changes in urban landscapes and there are no apparent extinction debts. Indeed, we found that habitat loss reduces species diversity to a new equilibrium in relatively short period (less than 10 years), and model projections indicate that bird richness will remain similar to the present if patch area is maintained. Habitat loss is the most important cause of species local extinctions in urban areas, and tropical cities could rapidly promote biodiversity by restoring forest cover.