PCA of local extinction events
Through principal component analysis (PCA), we estimated the degree of variation in the contributory variables. In the above, we identified eight variables that contributed to local extinction (contribution rate >1), and we used the sampling method in GIS (version 10.4) to extract the information of associated environmental variables, including population count, elevation, cropland, grazing, bio4, bio9, bio15 and bio19, of the 314 extinction records in 1970-2000 to analyze the principal components of local extinction events of Chinese pangolin.