Rapid deforestation threatens mid-elevational endemic birds but climate change is most important at higher elevations

Abstract

Aim: Deforestation and climate change are two of the most serious threats to tropical birds. Here, we combine fine-scale climatic and dynamic land cover models to forecast species vulnerability in rain forest habitats. Location: Sulawesi, Indonesia. Methods: We sampled bird communities on four mountains across three seasons in Lore Lindu National Park, Sulawesi, Indonesia (a globally important hotspot of avian endemism), to characterize relationships between elevation and abundance. Deforestation from 2000 to 2010 was quantified, and predictors of deforestation were identified. Future forest area was projected under two land use change scenarios – one assuming current deforestation rates and another assuming a 50% reduction in deforestation. A digital elevation model and an adiabatic lapse rate were used to create a fine-scale map of temperature in the national park. Then, the effects of climate change were projected by fitting statistical models of species abundance as a function of current temperature and forecasting future abundance based on warming from low- and high-emissions climate change. Results: The national park lost 11.8% of its forest from 2000 to 2010. Model-based projections indicate that high-elevation species (white-eared myza Myza sarasinorum and Sulawesi leaf-warbler Phylloscopus sarasinorum) might be buffered from deforestation because their ranges are isolated from human settlement, but these species may face steep population declines from climate change (by as much as 61%). The middle-elevation sulphur-bellied whistler Pachycephala sulfuriventer is predicted to undergo minor declines from climate change (8–11% reduction), while deforestation is predicted to cause larger declines of 13–19%. Main conclusions: The biological richness and rapid deforestation now occurring inside the national park emphasize the need for increased enforcement, while our modelling suggests that climate change is most threatening to high-elevation endemics. These findings are likely applicable to other highland tropical sites where deforestation is encroaching from below and climate change is stressing high-elevation species from above.