Streak-backed Antshrike

The streak-backed antshrike is 16 to 17 cm (6.3 to 6.7 in) long and weighs 22 to 30 g (0.78 to 1.1 oz). Members of genus Thamnophilus are largish members of the antbird family; all have stout bills with a hook like those of true shrikes. This species exhibits slight sexual dimorphism. Adult males of the nominate subspecies have a black crown and nape with a few white feathers on them. Their upperparts are black with a white patch between the scapulars that shows as spots or streaks. Their wings, scapulars, and wing coverts are black with white spots and edges. Their tail is black with white spots and tips on the outer feathers. Their underparts are gray with a somewhat lighter belly. Adult females resemble males in most ways. Their forehead has faint white spots, their rear crown is dark red-brown, and their underparts are somewhat paler than the male's. Males of subspecies T. i. nigrifrontalis are the same as the nominate; females have an entirely black (unspotted) forehead.

The nominate subspecies of the streak-backed antshrike is found on the tepuis where southeastern Venezuela's Bolívar and Amazonas states, extreme western Guyana, and extreme northern Brazil meet; most of that range is in Venezuela. Subspecies T. i. nigrifrontalis is found on the Cerro Sipapo massif in southern Amazonas state. The species inhabits the understorey to mid-storey of humid montane evergreen forest. It favors areas of stunted trees with a dense understorey dominated by Melastoma and Clusia vegetation and also occurs in bamboo thickets and Brocchinia scrub. It ranges between 900 and 2,000 m (3,000 and 6,600 ft) in elevation, though it is more common above 1,200 m (3,900 ft).

The streak-backed antshrike's diet has not been detailed but is mostly insects and other arthropods. It usually forages singly and in pairs, mostly between 1 and 5 m (3 and 16 ft) of the ground though sometimes as high as 10 m (33 ft). It hops through vegetation, gleaning prey from leaves, branches, bamboo, and individual vines and vine tangles and captures prey with reaches and lunges from a perch. It occasionally joins mixed-species feeding flocks.