Adults of the nominate subspecies G. b. bicolor have a brownish chestnut crown and nape.

[9][10][11] Subspecies G. b. olivascens of the bicolored antbird is much like the nominate but is dull brown behind the eye rather than gray.

G. b. ruficeps has a brighter rufous forehead and crown than aequatorialis, is blacker behind the eye, and has a darker reddish back and redder sides.

It is dominant over smaller antbirds but subordinate to larger species of other families such as woodcreepers.

Its known nests are cups made from dead palm and other leaves, often with a lining of fungal rhizomorphs.

The bicolored antbird's primary song is "a series of high notes which increase in pitch and pace, then slow down and descend".

[12] Its calls are essentially the same as those of the white-cheeked antbird and include a "harsh, vibrant 'chirr'...diminishing slightly in pitch and intensity, and abrupt 'chup' notes, usually doubled but also in groups of 3–4".

However, "local populations in Honduras, Nicaragua and parts of Costa Rica and Panama have declined or disappeared as entire regions have been cleared for human settlement and agriculture".