Behavior

Foraging

Individuals (typically; see Skutch 1996) or two or three birds (generally at ant swarms; Willis 1985, Skutch 1996) forage terrestrially, in part by sweeping the bill from side to side through leaf litter (Clark 1971) or by flicking away or tossing leaves (Skutch 1945, Willis 1985); Black-faced Antthrush does not scratch with its feet in search of food (Skutch 1945). An antthrush forages as it walks deliberately, "tilting forward, its short black tail held erect" as it "moves in wide circles over the forest floor within its territory"(Skutch 1996: 88–89). Most birds forage in open to moderately vegetated understory, but an occasional bird "wanders under dark logs or in dense seedlings" (Willis 1985). Virtually all prey is taken from the ground, with ca 75% of captures the result of birds pecking at prey while they remain stationary and another ca 12% from pecking as they pursued the prey (Willis 1985). Only rarely (<1% of instances; Willis 1985) will a bird leap from the ground to launch a sally after escaping prey.

Black-faced Antthrush attends ant swarms—predominantly (92.8% of recorded swarms) of Eciton burchelli but sometimes of Labidus praedator (Willis 1985)—although it does not do so routinely (Chaves-Campos 2003). An antthrush remains at the edges of a swarm (Skutch 1996), generally at the leading edge of the ants and seldom captures prey within a swarm (Willis 1985). If an individual must cross through a swarm, it will run or flutter-hop to avoid stings on its feet and legs (Willis 1985). The species deserts a swarm whenever a forest-falcon (Micrastur sp.) appears (Willis 1985).

Nutrition and Energetics

No information.

Metabolism and Temperature Regulation

No information.

Drinking, Pellet-Casting, and Defecation

No information.

Locomotion

This species is chiefly terrestrial, although it will traverse horizontal roots and logs (Willis 1985). It moves about by walking (as opposed to hopping) in a rail-like fashion (Skutch 1945, 1996), with its tail cocked at an angle of ca 60º above the ground, with this angle "pounded" down to 20º at each step (Willis 1985). An antthrush "occasionally flutters to cross a small cliff or log . . . even when undisturbed" (Willis 1985).

Self-Maintenance

An individual Willis (1985) observed in north coastal Brazil '“bathed in a tiny pool in the forest, dipping its breast and f1uttering the wings, and then scratched its head indirectly (over the wing)". Although little is known about preening behavior and related modes of self-maintenance, the chemical composition of the preen gland has been described in detail (Haribal et al. 2009).

In Amazonia, territory size averages 12–16 ha, twice that of its broadly sympatric congener Rufous-capped Antthrush (Formicarius colma) (Stouffer 1997), but territory size is much smaller in both Panama (5 ha) and Peru (6 ha) (Stouffer 2007). On the basis of song variation among individuals, and predicated on an ability to identify an individual given its song, male have high site fidelity but many females float across territories (Kirschel et al. 2011). Even so, territory occupancy varies considerably from year to year (Stouffer 2007).

Mates perhaps shares food between them, as habit noted in other antbirds (Skutch 1945). Pair bonds apparently exist only medium term and are not sustained through the lifetime of an individual (Kirschel et al. 2011).

Black-faced Antthrush usually is solitary.

Interspecific Behavior

Black-faced Antthrush may be competitively inferior to its congener Rufous-capped Antthrush (Formicarius colma) where the species co-occur (Stouffer 1997), even though Black-faced tends to be more aggressive toward heterospecific song (Robinson and Terborgh 1995) and tends to be rarer than the latter in some areas of sympatry (e.g., Amazonian Brazil; Cerqueira et al. 2013) but not in others (e.g., French Guiana; Stouffer 2007), variation that may affect assessments of competitive interactions. Moreover, Willis (1985) reported an instance wherein a single Black-faced "displaced" two Rufous-capped at an ant swarm. The two species co-occur at various locales in Amazonia (Robinson and Terborgh 1995).

Black-faced Antthrushes at ant swarms generally does not interact with other birds, but Willis (1985) reported that the species has been seen to chase off White-backed Fire-eye (Pyriglena leuconota), Bicolored Antbird (Gymnopithys bicolor), Spotted Antbird (Hylophylax naevioides), and Plain-brown Woodcreeper (Dendrocincla fuliginosa). When displacing a fire-eye, an antthrush ran at it "with tail lifted and spread wide, crissum fluffed out, back feathers raised, wingtips spread, bill open, and head down, pirouetting as it gave faint grunts" (Willis 1985). Bill snaps are used as well (Willis 1985).

Agonistic Behavior

When disturbed, an antthrush jerks its tail rapidly (Willis 1985). Typically it retreats silently, but occasionally a startled bird will utter one to several chips as its flushes a short distance, chips that "sometimes elicit songs or chipping notes from another bird" (Willis 1985).

No information.