A little passerine bird that is exclusive to Mexico’s highlands north of the Isthmus of Tehuantepec, the red warbler (Cardellina rubra) is a member of the Parulidae family of warblers. It forms a superspecies with the pink-headed warbler, which is native to Guatemala and southern Mexico. The two species are very closely related.

The three distinct species of this bird are identified by differences in plumage brightness and tone, as well as differences in the color of their ear patches, and by the fact that they inhabit separate populations. Depending on the species, adults show off a vivid red plumage that is accompanied by a white or gray ear patch. Its legs are a dull reddish-brown color, while its wings and tail are noticeably darker with pinkish-red edges.

There isn’t much of a difference in plumage between the sexes, though females are often somewhat paler or tinged with orange.

In addition to two pale wingbars and an ear patch that is white in color, juveniles display a pinkish-brown hue.

This species is unique to Mexico and can be found from the southern region of Chihuahua down to the southern tip of Hidalgo.

Forests of pine, pine-oak, fir, and, to a lesser degree, oak, situated at elevated elevations, are the preferred habitats of the red warbler. Altitudes of 2.000-3.500 m are where you can find them.

The female builds a ground-level dome nest and lays clutches of three or four eggs during mating season, which usually begins in February and lasts until May. Both parents help out with feeding the babies and keeping the nest clean, but she’s the one that has to incubate the eggs. Within 10–11 days after hatching, the larvae will begin to flee. As an insectivore, the red warbler finds much of its food among shrubs in the understory.

Typically, red warblers are observed singing alone or in pairs, however they will sometimes be seen as part of a mixed-species flock.