Ocellated Antbirds forage exclusively at army ant swarms (Willis 1973, Cody 2000, Chaves-Campos 2011). These ants perform daily raids, in which the colony spreads forward in a column from their bivouac site. As the ants move over the ground, they scare up arthropods from the leaf litter. Though the ants bring much of this prey back to the bivouac, some animals escape the swarming insects. A specialized guild of ant-following birds, including Ocellated Antbird, feeds on the arthropods flushed by the swarming army ants (Willis and Oniki 1978). Some, including Ocellated, are obligate army ant followers, and do not forage apart from ant swarms.
Various hypotheses exist for how these birds locate and track army ant swarms. Because these swarms are nomadic, antbirds must follow their location daily to keep tabs on them. Observers have noted that they check ant bivouacs daily, whereas more recent studies have suggested that they also take cues from conspecifics’ vocalizations and group knowledge to investigate new swarms (Willis 1973, Chaves-Campos 2011).
While foraging, Ocellated Antbirds generally perch on branches and stems within one meter of the ground. They move from perch to perch, looking for flushing arthropods. When a potential prey item flushes, they sally down to the ground to attack, then quickly fly back up to a perch to consume the prey (Willis 1973).
Ocellated Antbirds eat essentially anything of reasonable size flushed by the army ant swarm. Most prey items are under 25 mm in length, though they have been witnessed capturing small lizards and large cockroaches up to 55 mm long (Willis 1973).