Black-headed antthrush
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Passeriformes
Family:	Formicariidae
Genus:	Formicarius
Species:	F. nigricapillus
Binomial name
Formicarius nigricapillus Ridgway, 1893

The black-headed antthrush (Formicarius nigricapillus) is a species of bird in the family Formicariidae. It is found in Colombia, Costa Rica, Ecuador, and Panama.^[2]

The black-headed antthrush has two subspecies, the nominate F. n. nigricapillus (Ridgway, 1893) and F. n. destructus (Hartert, EJO, 1898).

The black-headed antthrush is about 18 cm (7.1 in) long; four individuals weighed 58 to 68 g (2.0 to 2.4 oz). The sexes have the same plumage. Adults of the nominate subspecies have a dark dusky brown to blackish crown. Their face and throat are black with a ring of bluish white bare skin around the eye. Their back, rump, and wings are dark chestnut-brown, their uppertail coverts dark rufescent brown, and their tail black. Their flight feathers have dusky inner edges and a wide cinnamon band at the base. Their upper breast is blackish gray, their belly gray, and their undertail coverts rufous. They have a brown iris, a black bill, and dusky brown legs and feet. Subspecies F. n. destructus has darker and less reddish-tinged upperparts than the nominate.^{[3][4][5][6][7][excessive citations]}

The black-headed antthrush has a disjunct distribution. The nominate subspecies is found on the Caribbean slope of Costa Rica and the Caribbean and Pacific slopes of Panama to western Guna Yala (San Blas). Subspecies F. n. destructus is found from central Chocó Department in Colombia south on the Pacific slope into Ecuador as far as eastern Guayas and northwestern Azuay provinces. The species inhabits humid to wet primary forest and mature secondary forest. It favors ravines and other areas that have dense undergrowth. In elevation it occurs between 400 and 1,200 m (1,300 and 3,900 ft) in Costa Rica, between 400 to 1,500 m (1,300 to 4,900 ft) in Panama, from near sea level to 1,400 m (4,600 ft) in Colombia, and from near sea level to 900 m (3,000 ft) in Ecuador.^{[3][4][5][6][7][8][excessive citations]}

The black-headed antthrush is a year-round resident throughout its range.^[8]

The black-headed antthrush feeds primarily on a variety of arthropods, mostly insects but including spiders, and also tiny reptiles and amphibians. It is almost entirely terrestrial. It walks slowly and deliberately with its tail cocked like a little rail. It probes crevices and tangles and flicks aside leaf litter to find prey. It sometimes follows army ant swarms to capture prey fleeing the ants.^[3][5][7]

The black-headed antthrush's breeding season varies geographically, from including April and May in Costa Rica and spanning at least December to March in Colombia. One nest was a shallow cup made of leaf petioles and dead leaves placed deep down in a hollow palm stump. The clutch size was two eggs. The incubation period, time to fledging, and details of parental care are not known.^[3]

The black-headed antthrush's song is "a trill of c. 10 notes per second at 1·5–2 kHz, first falling, then rising in pitch". Both sexes sing, commonly from the ground. Its call is "a short 'chweep' ".^[3]

The IUCN has assessed the black-headed antthrush as being of Least Concern. Its estimated population of at least 50,000 mature individuals is believed to be decreasing. No immediate threats have been identified.^[1] It is considered generally uncommon to locally fairly common, and specifically uncommon in Costa Rica and common in Colombia.^[3][5][6] It occurs in several protected areas and is "able to survive in isolated and fairly small patches of forest".^[3]