The Chestnut-backed Antbird is one of many secretive forest understory species that is far more often heard than seen. The song -- a two- or three-note whistle -- is a common feature of many lowland forests throughout the species’ range. Like most antbirds, the species has no special predilection for foraging at army-ant swarms, though it does so opportunistically when a swarm passes through a territory. The specific name exsul (“stranger” in Latin) may have reflected its sporadic appearance at ant swarms to early naturalists who believed all antbirds followed army ants. Unlike many forest-dwelling antbird species, the Chestnut-backed Antbird is often found in even small forest patches in fragmented landscapes, and it has flourished on Barro Colorado Island, Panama, despite being a demonstrably isolated population.