Appearance

Warbling-finches (Poospiza) are small to medium sized, slender, long-tailed finches; many species of warbling-finches are arboreal. Chestnut-breasted Mountain-Finch is large for a Poospiza, and is more terrestrial than are most other species of the genus. The upperparts are gray above, with a long white supercilium. The throat is white, bordered below by a broad chestnut band across the breast. The belly is white, but the flanks are gray, and the undertail coverts are chestnut, similar in color to the breast.

Chestnut-breasted Mountain-Finch is unlikely to be confused with any other species that occurs within its limited range. Plain-tailed Warbling-Finch (Poospiza alticola) of the Andes of northwestern Peru is smaller and more arboreal, and has rufous along the sides but not across the center of the breast. Perhaps Chestnut-breasted Mountain-Finch is most similar to the allopatric Black-and-rufous Warbling-Finch (Poospiza nigrorufa), from which it differs by its larger size, white (not rufous or chestnut) throat, gray flanks, and lack of white in the tail; and to the allopatric Bolivian Warbling-Finch (Poospiza boliviana), from which it differs by its larger size, grayer upperparts, gray flanks, chestnut undertail coverts, and lack of white in the tail.

The following description is based on Fjeldså and Krabbe (1990) and on Jaramillo (2011):

Adult: Sexes similar. Upperparts gray; lores and auriculars blackish, separated from the crown by a thin but distinct white supercilium. Throat white. Breast rufous (feathers with broad, pale buff tips when fresh). Flanks gray or gray brown. Belly white; vent and undertail coverts rufous.

Juvenile: Similar to the adult, but the areas that are predominately gray or blackish are tinged with brownish, and there is a faint buffy tinge on the throat.

Iris: brown, dark brown

Bill: maxilla black, mandible gray or black with a small gray area at base

Tarsi and toes: dark gray, blackish

Bare parts color data from Jaramillo (2011) and from specimens in the Field Museum of Natural History.

Total length: 17 cm (Fjeldså and Krabbe 1990), 18.5 cm (Ridgely and Tudor 2009)

Linear measurements: none reported?

Mass: not reported?