Appearance

As its English name implies, Black-faced Antthrush has a black face, a patch thatextends across the throat. The sides of the neck and the undertail coverts are rufous, and around the eye there is bare patch of bluish-white skin that widens posteriorly. The upperparts are brownish, with a variable extent of olive or rufescent, and the underparts vary from grayish to off-white to tan.

Black-faced Antthrush often is syntopic with Rufous-capped Antthrush (Formicarius colma) in Amazonia, but Rufous-capped easily is distinguished by its bright rufous crown, more extensive black on the foreparts, and gray (not rufous) vent. Locally in southwestern Amazonia, Black-faced also is syntopic with Rufous-fronted Antthrush (Formicarius rufifrons), which has a bright rufous forecrown, and lacks the black face. There is little (or no?) contact with Rufous-breasted Antthrush (Formicarius rufipectus) of the Andes, which has a distinctive dark rufous breast.

Adult: Sexes similar. Crown dusky brown. crown. Small white spot on the lores, and a bluish patch of bare skin around the eye, broader behind the eye. Otherwise the area between the bill and the eye is black, the black extending onto the sides of the head below the eye, down to the chin, throat, and upper breast. Nape, back, rump, and wings brown; uppertail coverts brown, tinged with rufescent. Inner webs of remiges dusky, with broad cinnamon band across base. Rectrices blackish brown. Upper breast dark gray, rest of underparts gray, paler on the centerr of the belly; flanks washed with brown. Undertailcoverts rufous.

See also Geographic Variation.

There are no comprehensive data on the specific timing or cycle of this species’s molt. That said, downy young do not acquire clearly visible pin feathers until 15 d old (Skutch 1996).

Hatchlings

Newly hatched birds are not naked but rather are "a featureless mound of dark gray down, exceptionally dense for a passerine bird" (Skutch 1996:94). Distinct whitish flanges are visible at the posterior edge of the gape, the gape itself being yellow (Skutch 1996).

Juvenile Plumage

A newly fledged bird, observed leaving its nest, looked "much like the adults" (Skutch 1996:97).

Basic I Plumage

No information.

Definitive Basic Plumage

No information.

Bill

Both the maxilla and mandible are black (Ridgway 1911), although in newly fledged birds the tip of the bill is whitish (Skutch 1996).

Iris

The irides are dark brown (Ridgway 1911), although under most field conditions the eyes simply look "dark".

Tarsi and Toes

The tarsi and toes may be anywhere from gray to bluish (Ridgway 1911).

Linear

Overall length 150–181 cm and wing chord 84–98 cm (Ridgway 1911), with the female averaging slightly (2–3%) smaller. Body size varies little geographically, with the largest birds in southern Central America and the smallest in the southeastern Amazon Basin.

Mass

On average, body mass (weight) does not differ between the sexes: both males (n = 27) and females (n = 14) average 56.5 g, although in terms of size range, male in general are slightly larger (48.0–69.0 g vs. 42.5–63.0 g). Body differs little across the wide geographic range of the species, with little of that variation correlated to wing chord.