Red Warbler

Overview

The red warbler (Cardellina rubra) is a small passerine bird of the New World warbler family endemic to the highlands of Mexico. It forms a superspecies with the pink-headed warbler and is currently classified as a species of Least Concern, although its population is thought to be declining due to habitat destruction.

Identification

• Adults are bright red overall, with either a white or dark gray ear patch depending on the subspecies, while wings and tail are a slightly darker, dusky red.
• Juveniles appear pinkish-brown with a whitish ear patch and two pale wingbars.
• The bird measures 12.5–13.5 cm in length and has a thin, pinkish-gray bill with a dark tip.
• Its song consists of a mix of short trills and richer warbles interspersed with high-pitched chips, often sung only during bright morning hours in the breeding season.

Habitat

Endemic to the highlands of Mexico north of the Isthmus of Tehuantepec, the species inhabits elevations ranging from 1,800 to 3,900 metres. It is an altitudinal migrant, moving between humid or semi-humid pine, pine-oak, and fir forests during the breeding season and lower-elevation oak forests in winter. The bird is fairly common in the country's interior and on adjacent slopes but does not occur along either coast.

Diet

As an insectivore, the red warbler gleans primarily in understory shrubs by moving slowly and deliberately through open areas, often using quick jabs into cracks in bark and pine needle clusters. It may also hover briefly to feed at pine needle clusters and flycatches in deciduous growth areas. Foraging often involves climbing and hanging head-down to probe bark and epiphytes, with activity declining in the late afternoon as the bird rests.

Did you know?

The red warbler contains alkaloids in its feathers that render it unpalatable, a characteristic noted as early as the 16th century when the Aztecs regarded a red bird matching its description as inedible.