Colima Warbler

Overview

The Colima Warbler is a plainly plumaged warbler notable mainly for its extremely restricted United States range, occurring reliably only in high-elevation oak-pine canyon woodland of the Chisos Mountains in Big Bend National Park, Texas, with the bulk of its range extending into the mountains of Mexico. Its overall gray-brown coloring is set off by a bright rufous-orange patch under the tail, a useful identifying feature at close range.

Because of its very limited U.S. distribution, this species is a sought-after target for birders, requiring a specific high-elevation hike to encounter within the country.

Feather Identification

• Overall coloring: Body feathers are gray-brown overall, generally plainer and less colorful than many other warblers, lacking any yellow or olive tones on the body.
• Undertail coverts: A bright rufous-orange patch of feathers under the tail is the most distinctive feature, standing out against the otherwise subdued plumage.
• Crown patch: A rufous crown patch is present in adults but usually concealed by overlying feathers, visible mainly at close range or when the crown feathers are disturbed.
• Eye-ring: A thin, pale eye-ring is present, adding subtle facial contrast.
• Wings: Wings are plain, without wing bars.
• Size: Slightly larger than many similarly patterned Leiothlypis warblers, with correspondingly fuller feathers.

Plumage Details

Adult males typically show slightly more developed rufous crown and undertail coloring than females, though the difference is subtle. Immatures are duller overall, with a less vivid rufous undertail patch and reduced or absent crown color, gradually developing more adult-like plumage with age.

A complete molt occurs on the breeding grounds in late summer, and plumage remains fairly stable through the year given the largely resident to short-distance migratory habits of this species within its restricted range.

Habitat & Range

Colima Warblers breed in high-elevation oak-pine canyon woodland, generally above a certain elevation threshold, most famously in the Chisos Mountains of Big Bend National Park, Texas, which represents the only reliable U.S. breeding location. The species' broader range extends through the mountains of northern and central Mexico.

Some populations undertake short elevational or latitudinal movements outside the breeding season, generally remaining within Mexico, while the Texas population is present seasonally during the breeding months.

Behavior & Field Notes

This warbler forages in oak-pine canyon woodland, gleaning insects from foliage and bark at a range of heights, generally within or below the canopy. It can be somewhat inconspicuous despite its restricted and well-known range, requiring patience to locate.

The nest is built on the ground, often on a slope within its canyon woodland habitat. The song is a trilled series of notes, broadly similar in structure to related Leiothlypis warblers. Because access to its only reliable U.S. location involves a significant elevation gain, sightings are often tied to a specific, well-known hiking route within its national park habitat.