CONCLUSION
Our study showed that the pattern of the mean elevational range size of birds in Lebu Valley was a hump-shaped pattern, and species mean elevational range size negatively correlated with annual temperature range and positively correlated with the normalized vegetation index. While habitat heterogeneity was weakly correlated with species mean elevational range size. These results showed that all the hypotheses examined in our study (the climate variability hypothesis, the ambient energy hypothesis, and the habitat heterogeneity) failed to predict the elevational range size pattern of breeding birds in Lebu Valley. Given the uncertainty in species range size pattern, the generality of related hypotheses explaining the mean range size of species pattern remains to be further tested. Moreover, species inflow intensity could directly impact the species richness pattern in addition to the environmental factors. Our study provided new insights into the relationship between species richness pattern and species range size.