Map of the study area and sampling locations. Solid line represents the distribution of Aegithalos bonvaloti and A. fuliginosus. Dotted line represents the approximate contact zone. Circles and triangles show the sampling locations of A. bonvaloti and A. fuliginosus, respectively. The colours of circles and triangles correspond to mitochondrial DNA (mtDNA) origin, with white for A. fuliginosus haplotypes and black for A. bonvaloti haplotypes. Elevation is represented by shading: lower elevations are shown lighter and higher elevations are shown darker. Insert: The dotted box represents the study region.