The Sooty Antbird appears to form a species-group with four other relatively large-bodied antbirds currently placed in Myrmeciza, all of whose males are predominantly very dark with red irides and pale blue periorbital skin; four of them, including the present species, are confined to upper Amazonia. The other species, Immaculate Antbird (Myrmeciza immaculata), occurs in Central America and northwest South America. Although the Sooty Antbird does not ordinarily join mixed-species foraging flocks, pairs or individuals of this species regularly follow army ant swarms, picking off arthropods fleeing their path, by waiting close to the ground. It inhabits the dense understory of lowland and foothill terra firme forests, below 1200 m, and is only rarely found in seasonally flooded areas. Like many congenerics, the breeding ecology of the Sooty Antbird remains poorly known.