Attractive small sparrow endemic to highlands in central Mexico. Favors dense brushy areas and flower banks in pine-oak forest. Often rather skulking, but also curious, popping up to investigate scolding groups of other birds and contributing its sharp, chipping calls to the mob. Usually in pairs, sometimes in small groups, foraging in weedy vegetation, less often on the ground. Note rusty cap, gray face, and bright yellow bib. Lacks white eyebrow of Rufous-capped Warbler, which often occurs in the same areas.