Narrow-billed Antwren

The narrow-billed antwren is 11 to 12 cm (4.3 to 4.7 in) long; one male weighed 8.2 g (0.29 oz). The species is sexually dimorphic and has a longish bill and tail. Adult males are mostly dark gray. Their wings and tail are a darker blackish gray, with white tips on the wing coverts and the outer tail feathers. The center of their throat and breast are black, their flanks white, and their undertail coverts have white bars. Adult females have a pale supercilium and a whitish eye ring. They have olive-brown upperparts with a grayer crown; the olive-brown becomes reddish yellow-brown on the uppertail coverts. Their wings are brown with pale cinnamon edges on the coverts and reddish edges on the flight feathers. Their tail is reddish brown. Their underparts are mostly yellow-ochre that is nearly whitish in the center of the belly; their flanks have some white.

The narrow-billed antwren has a disjunct distribution inland from the coast in the eastern Brazilian states of Bahia and Minas Gerais. It inhabits the understorey to mid-storey of deciduous forest. In part of Bahia it also occurs in mata-de-cipó, a biome characterized by a relatively open understorey and a few large emergent trees above a dense mid-storey. In elevation it ranges between 250 and 1,100 m (800 and 3,600 ft).

The diet of the narrow-billed antwren is not known in detail but includes insects and probably spiders. It typically forages singly, in pairs, or in family groups, and sometimes as part of a mixed-species feeding flock. It usually forages between about 1.5 and 8 m (5 and 26 ft) of the ground but occasionally on the ground and as high as 12 m (39 ft). It forages actively but methodically, picking at stems and limbs in woody vine tangles and on somewhat open branches while hitching along them. It also takes prey by gleaning from live leaves, clusters of dead leaves, and clumps of moss while perched, and sometimes makes short sallies from a perch to capture moths in flight.