Cercomacroides is a genus of antbirds in the family Thamnophilidae. These birds live in tropical areas from southern Central America to northern South America. There are six known species in this genus. They mostly live in the Amazon rainforest and on the east side of the Andes Mountains.These birds used to be part of the genus Cercomacra, but scientists made a new genus in 2014 after studying their DNA.The genus Cercomacroides includes six confirmed species. All species are classified as “Least Concern” (LC) by the International Union for Conservation of Nature (IUCN).
These birds are small. Males are black or dark grey. Females are orange-brown or olive. There is clear sexual dimorphism. They live in tropical rainforests and feed on insects. Some species follow army ants to catch prey. Their songs are duets between mates, but not sung at the same time. This is a key trait of the genus. Their nests hang between vines or shrubs. Both parents build the nest, sit on the eggs, and feed the chicks.
Morphological characteristics Cercomacroides are small to medium-sized antbirds. Their body length is about 12 to 14 cm, and they weigh between 15 and 25 grams. Their bills are black or dark grey. The upper bill is slightly curved, and the lower bill is straight. They have short wings and cannot fly far. They usually move by hopping or short flights. Their tails are long and slightly wedge-shaped. Their wings are short and round, which helps them move quickly through thick plants. Their legs are strong and dark grey or lead-colored. This helps them climb and jump on the ground or between branches.
Male birds are mostly black or dark grey. Their plumage is even, with no clear markings. Their tail feathers are one dark color without white tips. This is a key difference from the Cercomacra genus. Female birds have warmer colors, such as orange-brown, yellow-brown, or olive. The color difference between males and females is clear. Sexual dimorphism is common in this genus. The feathers on the face are dense and provide protection. Young birds have lighter plumage, usually brownish-yellow or olive, with pale edges on the feathers. It is hard to tell male and female chicks apart in the early stages.
Differences between species This table compares six species within the genus Cercomacroides, outlining key differences in male and female plumage and distinctive features used for identification. Species NameMale FeaturesFemale FeaturesIdentification HighlightsWillis’s Antbird
C. laetaAll black, throat slightly orange, tail feathers blackBrownish-orange, wing and ear feathers orange, body slenderFemale has shorter tail, head is slightly brighterBlackish Antbird
C. nigrescensDark grey, white edges on wing feathers, clear shoulder markDark brown, underparts orange-brownHigh variation by region, males have darkest plumageDusky Antbird
C. tyranninaSlate grey, lighter throat, iris brownBrown to yellow-brown, warm tone on lower bodyObvious regional differences, medium-dark overall colourParker’s Antbird
C. parkeriSlate grey, slightly brown, longer tailGrey-brown with yellow-brown, shoulder mark reduced or missingLongest tail, smaller body sizeBlack Antbird
C. servaBlack to dark grey, white edges on wing tipsGreyish brown, red or yellow tint on underpartsSouthern birds are darker, white wing edge very clearRiparian Antbird
C. fuscicaudaDark grey with bluish shine, small white spot on shoulderBrownish orange, lighter back, tail edges orange-brownWhite tail edges, cleanest and simplest plumage among species
Distribution Species of the genus Cercomacroides are found from southern Central America to northern South America. They are mainly distributed in the Amazon Basin and on the eastern slopes of the Andes Mountains. Their range includes southern Mexico, Costa Rica, Panama, Colombia, Venezuela, Ecuador, Peru, and northern Brazil. While some species share overlapping areas, most have specific regional centers.
Recognized Species The genus Cercomacroides now includes the following 6 confirmed species: ImageEnglish NameScientific NameDistribution AreaWillis’s AntbirdCercomacroides laetaCentral Amazon in Brazil, northeast of Pará StateParker’s AntbirdCercomacroides parkeriCentral-west Colombia, Andes Mountains (around 1100–1950 m elevation)Blackish AntbirdCercomacroides nigrescensTropical forests in northern South AmericaRiparian AntbirdCercomacroides fuscicaudaEastern to southeastern Colombia, northwestern Brazil and PeruDusky AntbirdCercomacroides tyranninaFrom southeast Mexico, through Central America, to northwest Ecuador and many parts of the AmazonBlack AntbirdCercomacroides servaFrom southeastern Colombia to northern Bolivia and northern Brazil
Conservation status According to the IUCN Red List, all six species of Cercomacroides are currently classified as “Least Concern” in terms of global conservation status. They are mostly found in tropical rainforests and secondary forests in South America. Some species can live well in disturbed habitats such as forest edges, secondary growth, and bamboo areas. This makes them less sensitive to human activities compared to other forest birds.
However, there are still clear differences in range and population status among the species. The Black Antbird, Dusky Antbird, and Riparian Antbird have wide distributions and stable populations. They are found in several national parks and are considered common or fairly common.
In contrast, Parker’s Antbird and the Blackish Antbird have smaller ranges. They mostly live in specific elevation zones in the Andes Mountains. Their population sizes are limited, and they face some risk from habitat loss.
Overall, this genus shows good adaptability to secondary forests, which gives it more resilience than many other understorey birds.
Taxonomic history Cercomacroides was originally part of the genus Cercomacra. For many years, Cercomacra was seen as a uniform and monophyletic genus based on its physical traits. However, as scientists studied the behavior and vocal patterns of antbirds more closely, they began to question whether Cercomacra was truly as unified as it appeared.
In the early 1990s, scientists divided the genus Cercomacra into two informal groups. They used female plumage and song behavior to make this division. The two groups were called the “nigricans group” and the “tyrannina group.” However, this division had no strong phylogenetic evidence. So, it was not widely accepted.
In 2014, Tello and colleagues published a study in the Zoological Journal of the Linnean Society. They used mitochondrial and nuclear genes (ND2, ND3, CYTB, and FIB5) to analyze relationships. They built a phylogenetic tree using maximum likelihood and Bayesian methods. Their results showed that Cercomacra was polyphyletic. It included two unrelated lineages.
One of these lineages, led by Cercomacra tyrannina, was moved to a new genus: Cercomacroides. The South American Classification Committee (SACC) approved this change under Proposal No. 638.
The name Cercomacroides comes from three Greek roots: cerco- meaning “tail,” -macr- meaning “long,” and -oides meaning “similar to.” The full name means “a group similar in appearance to Cercomacra,” highlighting its visual similarity while recognizing its separate evolutionary lineage.
The new genus originally included five species: C. tyrannina, C. serva, C. nigrescens, C. laeta, and C. parkeri. In 2014, Mayer and colleagues identified fuscicauda as a separate species from C. nigrescens (SACC Proposal No. 636), increasing the total number of species in the genus to six.
Diet and habitat Antbirds in the genus Cercomacroides mainly feed on insects. Including beetles, grasshoppers, lepidopteran larvae, orthopterans, homopterans, and spiders, as well as other arthropods. By eating insects, Cercomacroides species act as natural pest controllers in the rainforest. They help reduce insect damage and support the balance of plant communities. These birds mostly live in the understorey of tropical lowland rainforests. They prefer dark, humid areas with dense vegetation, such as primary forests, mature secondary forests, and edges of degraded woodlands.
They are usually seen alone, in pairs, or in small family groups. They forage mainly between ground level and 5 meters high. They do not usually join mixed-species flocks. Their behavior is active but calm. They move in short hops, often pausing for a few seconds between jumps to look for prey. Their body posture can vary from almost horizontal to nearly upright, and their tails are held flat or slightly raised. While foraging, they may gently flick their wings. They search for prey among shrubs, fallen logs, vines, and leaf litter. Sometimes, they jump to the ground and flip over leaves to find food. Their movements are quick and flexible, which helps them move through the complex forest understory. They often pause briefly to watch for prey, then quickly strike from behind leaves, under branches, or among fallen leaves on the ground. Sometimes, they hang upside down from branches or climb vines to catch food.
Some species, such as C. tyrannina and C. nigrescens, sometimes follow army ants like Eciton burchellii. These ants move quickly through the forest and flush out many small animals, creating a chance for birds to catch exposed prey. Cercomacroides birds often forage in front of the ant swarm, catching insects that try to escape. This behaviour is called "ant-following foraging." However, Cercomacroides are not fully dependent on this method. They are considered "facultative ant-followers," meaning they only show this behavior in certain areas and at certain times.
These birds are highly adaptable and can forage successfully in both primary and secondary forests. They play an important role in the food web of the tropical forest understory.
Breeding The breeding behavior of Cercomacroides has not been fully studied, but some field observations have provided basic information.
Birds in this genus usually build their nests in low plants within tropical or secondary forests. Nests are typically placed between vines, shrubs, or small branches. They are well hidden and located about 0.5 to 2 meters above the ground. The nest has a deep pouch shape with a slightly upward-tilted opening. It is loosely woven but firmly attached using fine vines, moss, dry leaves, and plant fibers. In many species, the back of the nest is much higher than the front, giving the entrance a clearly slanted angle—this is a common feature across the genus. Nests are mostly attached to vertical plant structures, such as hanging fern stems or vines. The plant passes through the back of the nest, helping it hang securely. A few nests are found on horizontal bamboo branches, where the entrance becomes more circular. This nest shape helps with camouflage and may also reduce the risk of predators. The nest is made of two layers. The outer layer is built from green moss, black fern roots, bark, and dry bamboo leaves. The inner layer is made of fine bamboo leaves, fern pieces, and black thread-like fibers. The inside is soft and stable, making it suitable for incubation and chick care.
During the study, some nests were attacked by predators, especially lizards such as Tupinambis teguixin. This shows that even though the nests are well hidden, they still face some risk from predators.
Both male and female birds take part in building the nest, incubating the eggs, and feeding the chicks, showing a cooperative breeding style. Each nest usually contains two eggs. The eggs are beige or pale yellow with reddish-brown spots. The incubation period lasts about 14 to 20 days.