Environmental niche modeling of the Nanling Range
ENM of the habitats of the 5 target species during the LGM (21,000 years ago) and the onset of the BAW (14,600 ybp) indicates that the range of all of them would have shifted largely to the eastern end of the Nanling Mountains, while a few discrete probability peaks remained within the rest of the range. During this time, the Nanling Mountains formed the approximate northern edge of warm forest vegetation in China (figure 4 in Tian et al. 2018a). As expected with global warming after ~14,600 years ago and a concomitant increase in suitable habitat, the species expanded their distributions westward across the mountains (Supporting information). The key conclusion of ENM is that the Nanling Mountains provided refugial habitat to sustain the 5 species during the LGM. No doubt, conditions in the mountains sustained many other bird species as well.