Cercomacra

Species of Cercomacra are small to medium-sized antbirds, measuring approximately 13 to 16.5 cm (5.1 to 6.5in) in length and weighing between 14 and 20 grams (0.49 to 0.71 oz). They display strong sexual dimorphism in plumage. Males have predominantly black or dark gray plumage with distinctive white spots or tips on their tail feathers.^{[14][15][16][17][18][19][20][21]} Females display more subdued olive-grey or greyish-brown plumage. In contrast, females of Cercomacroides usually display tawny-buff plumage.^[10]

Cercomacra species communicate with each other through complex vocal duets.^[10][22] These coordinated songs are usually performed between paired males and females. This kind of communication behaviour plays a central role in defending territory, strengthening partner bonds, and facilitating reproductive isolation between close relatives who share similar habitats. The structure of these vocalizations usually consists of rapid, rhythmic, short note exchanges with a distinct arrangement between males and females. In addition to vocal duets, Cercomacra species also exhibit visual behaviors such as tail flicking and subtle wing movements, especially during territorial displays or close interactions. These actions may enhance the transfer of their acoustic signals.^[8][10]

Species of the genus Cercomacra typically place open, cup-shaped nests horizontally in dense vine tangles or low vegetation in tropical forests. In contrast, Cercomacroides species build deep pouch-like nests suspended from vegetation.^[10] Nest placement and construction provide camouflage and protection from predators and inclement weather. These nests are usually relatively close to the ground or in the understory of the forest. Male and female birds share nesting duties, which include building, incubation, and feeding. Those behaviours can reinforce their strong pair bond.^{[14][15][16][17][18][19][20][8]}

Cercomacra species are insectivorous. They usually find food in leaves and branches of the understory and mid-canopy.^[10][8][23] Of the 131 existing avian families, more than 11% interact with ants. Among them, antbirds – including the genus Cercomacra – stand out particularly in tropical biomes, where they engage in complex relationships such as symbiosis, competition and predation.^[24] In studies of antbird genera, there is evidence that antbirds exhibit colony-following behavior.^[25] Unlike other antbirds, Cercomacra is regarded as an opportunistic participant in this interaction, benefitting from the prey of the ant colony.^[23]

Cercomacra often hides in dense vegetation. During their vocal displays, individuals may move to more exposed branches to have better transmissions.^[8] Their perching behaviour is usually brief, followed by quick and agile jumps or flights to feed or patrol their territory.^[10][8][23]

Species of Cercomacra are distributed across neotropical regions in the Amazon basin and adjacent lowland rainforests. Most species are found in the humid tropical forests of the Amazon. Some, such as Cercomacra brasiliana, are limited to Brazil's Atlantic Forest.^[21] Cercomacra manu inhabits bamboo-dominated forests in the foothills of the Andes.^[26] Cercomacra species can also be found in Colombia, Venezuela, Brazil, Peru, Bolivia, and Guyana.^{[10][14][15][16][17][18][19][20]}