Ecological niche models for Aegithalos bonvaloti and A. fuliginosus . The LGM represents the Last Glacial Maximum. Circles and triangles represent the localities used to build ecological niche models for A. bonvaloti and A. fuliginosus, respectively. Blue represents the potential distribution for A. bonvaloti, red for A. fuliginosus, and dark blue for the contact zone between the two species. The dotted area shows the Sichuan Basin.