The Red Warbler (Cardellina ruber) is a small passerine bird endemic to the highlands of Mexico, north of the Isthmus of Tehuantepec. It is closely related to, and forms a superspecies with, the Pink-headed Warbler of southern Mexico and Guatemala. There are three subspecies, found in disjunct populations, which differ primarily in the color of their ear patch and in the brightness and tone of their body plumage. The adult is bright red, with a white...