Fig. 1

Scatter plots of bird species richness, phylogenetic structure (Phylo NRI) and functional structure (Funct NRI) against their three most associated variables assessed by ordinary least squares (OLS) models, which were mean annual temperature (MAT), plant species richness (Plant SR) and mean annual precipitation (MAP) for species richness, glacial-interglacial velocity in MAP (Velo MAP), glacial-interglacial velocity in MAT (Velo MAT), and campus age (Age) for Phylo NRI, MAP, campus area (Area) and Velo MAP for Funct NRI, respectively. Linear regression fits and r² were given. Dashed lines represented that the correlations were not significant. *p < 0.05