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En bref

  • Scientific Name: Formicarius nigricapillus
  • Spanish Name: Hormiguero cabecinegro
  • Family: Formicariidae
  • Known Nicknames: Black-headed Ant-thrush
  • Average Length: 18–20 cm / 7–8 in
  • Average Weight: 50–70 g / 1.8–2.5 oz
  • Envergure : N/A
  • Key Feature: Black hood contrasting with rufous-brown body and white throat
  • Régime alimentaire principal : Insectivore
  • Range: Caribbean slope of Costa Rica and western Panama
  • Habitat: Humid lowland and foothill forest floor
  • Structure sociale : Solitaires ou en couples
  • Nesting/Breeding: Domed nest on or near ground in dense vegetation
  • Statut de conservation : Préoccupation mineure (LC)
  • Évolution démographique : Stable

The Black-headed Antthrush (*Formicarius nigricapillus*) is a secretive, thrush-like bird of the humid lowland forests from Costa Rica to Ecuador, renowned for its striking appearance and elusive nature. Its most unique characteristic is its bold plumage: a rich, deep chestnut body contrasts sharply with a jet-black hood covering the head, throat, and upper breast, while a vivid, sky-blue patch of bare skin encircles the eye, giving it an intense, watchful expression. A stout, pointed black bill and strong legs suit its terrestrial lifestyle, as it forages alone on the forest floor, flipping leaf litter with its bill in search of insects and spiders. Special features include a loud, haunting song—a series of clear, descending whistles often heard at dawn—and a peculiar habit of bobbing its tail and head while walking, which helps birders spot this otherwise master of camouflage in the dim understory.

Faits amusants

Despite its name, the Black-headed Antthrush rarely sings from the ground; males often climb a low perch to deliver a haunting, descending whistle that sounds eerily like a human sigh, a vocalization that can carry for hundreds of meters through dense understory. It has an unusual foraging strategy called "ant-following," where it trails army ant swarms to snatch insects and small vertebrates fleeing the chaos, but unlike some antbirds, it is a solitary specialist that aggressively defends its spot from other followers. Its legs are disproportionately long and powerful, allowing it to kick leaf litter with surprising force to flush out hidden prey. Perhaps its quirkiest trait is a rapid, jerky head-bobbing while walking, which combined with its entirely black head and chestnut body, makes it look like a tiny, mechanical robot scouring the forest floor.

Habitats et répartition

The Black-headed Antthrush is confined to the humid lowlands and foothills of the Caribbean slope from eastern Honduras and Nicaragua south through Costa Rica and Panama into the Chocó region of western Colombia and northwestern Ecuador. It inhabits the dense, dark understory of mature tropical rainforest, particularly favoring areas near streams, swampy ground, and ravines where leaf litter is deep and moisture is high. The species is generally found from sea level up to about 1,200 meters in elevation, though it is most common below 700 meters.

Comportements & Reproduction

The Black-headed Antthrush is a solitary and highly territorial bird, with pairs maintaining a defended area year-round. Mating is monogamous, and courtship involves vocal duets, where the male and female coordinate their loud, descending whistles to reinforce pair bonds and signal territory ownership. The female builds a bulky, domed nest of leaves and twigs, typically placed in a tree cavity or on a palm frond, and lays two white eggs. Both parents share incubation duties for about 17–19 days, and the chicks are altricial, fed by both adults until fledging. A unique reproductive strategy involves the pair’s use of ant-following behavior; they forage near army ant swarms to capture flushed invertebrates, which provides a protein-rich diet critical for feeding nestlings during the breeding season.

Alimentation

The Black-headed Antthrush is an insectivorous bird, with its diet consisting almost entirely of terrestrial invertebrates. It forages exclusively on the forest floor, using its strong legs to hop and walk through leaf litter while flipping leaves and debris with its bill to uncover prey. Its primary food sources include ants, beetles, cockroaches, spiders, and centipedes, with a particular fondness for large ants and their brood. Interestingly, this species is known to follow army ant swarms, not to eat the ants themselves, but to capture other insects and small arthropods fleeing the swarm’s advance, a behavior known as “ant-following” that provides a concentrated feeding opportunity. Unlike some other antbirds, it does not consume fruit or seeds, making it a strict carnivore focused on ground-dwelling prey.

Couleurs

The Black-headed Antthrush has a slate-black head, throat, and upper breast, contrasting sharply with its warm olive-brown back, wings, and tail. Its underparts are pale gray to whitish, with fine dark scaling or mottling on the lower breast and belly that provides excellent camouflage against the dappled forest floor. A small, pale blue-gray patch of bare skin around the eye is a unique facial marking.