Xinyuan Pan, Dan Liang, Wei Zeng, Yiming Hu, Jianchao Liang, Xinwen Wang, Scott K Robinson, Xu Luo, Yang Liu

We explored the elevational richness patterns of birds in a biodiversity hotspot in south-western China, the Gaoligong Mountains and assessed the role of different spatial factors, climatic factors and landscape composition in shaping the richness patterns. The east slope of the southern part of Gaoligong Mountains (24.79°N-26.49°N, 98.65°E-98.93°E) is the western-most part of the Hengduan Mountains, China. We conducted field surveys of birds at each 300-m band from 700 to 3400 m a.s.l., and for the two bands from 3400 to 4000 m a.s.l., we obtained data from historical records. We obtained climatic recording data from local meteorological stations that were located in our study area and calculated the mean annual temperature and precipitation. We also calculated the area, MDE (the mid-domain effect), NDVI (the normalized difference vegetation index), habitat heterogeneity and human disturbance for each 300-m band. We then used multiple regression analysis to test the explanatory power of different factors for the elevational richness patterns of overall, endemic, non-endemic, large-ranged, and small-ranged birds. A total of 277 breeding bird species were recorded. We found consistent hump-shaped patterns of species richness with elevation with varied peaks for different groups. The richness of endemic birds peaked at higher elevation than non-endemic birds. Temperature and human disturbance played important roles in shaping the richness patterns of most bird groups whereas MDE contributed to the richness pattern of large-ranged species. Although none of the seven factors (area, MDE, mean annual temperature, annual precipitation, NDVI, habitat heterogeneity and human disturbance) showed consistent explanatory power among different species groups, temperature and human disturbance correlated well with most bird groups, indicating that more studies are needed in this biodiversity hotspot to clarify the detailed influence of anthropogenic activities and climate change on elevational distributions of birds.