email a friend
printable version
Unicoloured Antwren Myrmotherula unicolor
BirdLife is updating this factsheet for the 2016 Red List
Please email us with any relevant information

This species is restricted to primary forests within a small range, and is suspected to be have a moderately small and declining population owing to habitat loss and degradation. It is therefore listed as Near Threatened.

Taxonomic source(s)
SACC. 2006. A classification of the bird species of South America. Available at: #

Taxonomic note
Myrmotherula unicolor (Sibley and Monroe 1990, 1993) has been split into M. unicolor and M. snowi following SACC (2005). Note that snowi was described as a new subspecies of M. unicolor by Teixeira and Gonzaga (1985).

9.5 cm. Small, uniformly plain antwren. Male all grey, somewhat paler below, most with small, blackish throat patch. Female fulvous-brown above, olivaceous-buff below with whitish throat. Russet tail. Similar spp. All sympatric Myrmotherula have pale tips to coverts. Female Salvadori's Antwren M. minor has indistinct pale buff covert tips, but is less rufescent above with grey crown, brighter underparts and shorter tail. Voice Male song is short, high, plaintive eeeeeee. Raspy and strident plee-e contact calls.

Distribution and population
Myrmotherula unicolor is largely restricted to the lower slopes and coastal plain seaward of the Serra do Mar in Rio de Janeiro and São Paulo, with records also from Santa Catarina, south-east Brazil (Whitney and Pacheco 1995, do Rosário 1996, Naka et al. 2011). More recently, the species has been recorded from a number of new localities, and sites where it is present include: Torres, Itati (Rio Grande do Sul) (Bencke et al. 2000); Salto do Piraí (Naka et al. 2000), environs of Babitonga bay (Naka et al. 2000) and Serra do Tabuleiro state park (BirdLife International 2000) (Santa Catarina); Guaratuba area (Paraná) (Straube 1990); throughout the forests of the Serra de Paranapiacaba and Serra do Mar ranges (São Paulo); Ilha Grande State Park (Buzzetti 2000), lowlands of Serra da Bocaina National Park and Cairuçu Environmental Protection Area (Buzzetti 2000), Tijuca National Park (Whitney and Pacheco 1995), Tinguá Biological Reserve (Wege and Long 1995), União Biological Reserve (Whitney and Pacheco 1995), Serra dos Órgãos National Park (Scott & Brooke 1985), Poço das Antas Biological Reserve (Scott & Brooke 1985) and Desengano State Park (Whitney and Pacheco 1995) (Rio de Janeiro). There are historical records from Paraná and extreme north Rio Grande do Sul (Whitney and Pacheco 1995).

Population justification
Based on the discovery of additional localities and an improved understanding of its range and status, the population is now estimated to exceed 10,000 individuals (Birdlife International 2007).

Trend justification
Although data on population trends are lacking, moderate declines are suspected to be on-going, owing to rates of habitat loss and degradation within the range.

It inhabits both undisturbed and second growth humid forest, with a canopy height of 8-10 m and an abundance of vines and suspended dead leaves in the undergrowth. It also occurs in coastal restinga woodlands with a canopy of c.8-12 m but, in south São Paulo, it is largely found in the taller, humid forests that replace restinga (Whitney and Pacheco 1995). Although it reaches elevations of 500 m, most records are below 200 m (Whitney and Pacheco 1995). It frequently associates with mixed-species flocks (Whitney and Pacheco 1995, Whitney and Pacheco 1997).

Virtually all lowland Atlantic forest outside protected areas has been deforested within its historical range, and even some of the reserves where it occurs are not secure. The lowlands and foothills of south Rio de Janeiro and São Paulo have become easily accessible to humans since the 1970s, with most of the lower forest cleared or heavily degraded (Whitney and Pacheco 1995). Recreational developments in São Paulo severely threaten the integrity of sand-ridge restingas (Willis and Oniki 1992).

Conservation Actions Underway
Conservation Actions Proposed
Repeat surveys of known sites to determine rates of range contraction and population trends. Conduct surveys of suitable habitats within and surrounding the known range to determine its true distribution and abundance. Gazette remaining tracts of primary forest for future protection. Ensure the de facto protection of Serra da Bocaina National Park and Serra do Mar State Park. Promote environmental awareness in communities near reserves (Whitney and Pacheco 1997).

Aleixo, A.; Galetti, M. 1997. The conservation of the avifauna in a lowland Atlantic forest in south-east Brazil. Bird Conservation International 7: 235-261.

Bencke, G. A.; Kindel, A.; Mähler, J. K. F. 2000. Adiçoes à avifauna de Mata Atlântica do Rio Grande do Sul. In: Alves, M.A.S.; da Silva, J.M.C.; Van Sluys, M.; Bergallo, H.G.; Rocha, C.F.D. (ed.), A ornitologia no Brasil: pesquisa atual, conservaçao e perspectivas, pp. 317-323. Sociedade Brasileira de Ornitologia, Brasilia.

BirdLife International. 2000. The Development of Boundary Selection Criteria for the Extension of Breeding Seabird Special Protection Areas into the Marine Environment. OSPAR Convention for the Protection of the Marine Environment of the North-East Atlantic. Vlissingen (Flushing).

Buzzetti, D. R. C. 2000. Distribuicao altitudinal de aves em Angra dos Reis e Parati, sul do Estado do Rio de Janeiro, Brasil. In: Alves, M.A.S.; Silva, J.M.C.; Sluys, M.V.; Bergallo, H.G.; Rocha, C.F.D. (ed.), A ornitologia no Brasil, pesquisa atual e perspectivas, pp. 131-148. Eduerj, Rio de Janeiro.

do Rosário, L. A. 1996. As aves em Santa Catarina: distribuiçao geográfica e meio ambiente. Glorianópolis, Santa Catarina, Brazil.

Naka, L. N.; Barnett, J. M.; Kirwan, G. M.; Tobias, J. A.; de Azevedo, A. G. 2000. New and noteworthy bird records from Santa Catarina state, Brazil. Bulletin of the British Ornithologists' Club 120: 237-250.

Naka, L.N. 2011. Avian distribution patterns in the Guiana Shield: implications for the delimitation of Amazonian areas of endemism. Journal of Biogeography 38(4): 681-696.

Scott, D. A., Brooke, M. de L. 1985. The endangered avifauna of southeastern Brazil: a report on the BOU/WWF expeditions of 1980/81 and 1981/82.


Wege, D. C.; Long, A. J. 1995. Key Areas for threatened birds in the Neotropics. BirdLife International, Cambridge, U.K.

Whitney, B. M.; Pacheco, J. F. 1995. Distribution and conservation status of four Myrmotherula antwrens (Formicariidae) in the Atlantic Forest or Brazil. Bird Conservation International 5(2/3): 421-439.

Whitney, B. M.; Pacheco, J. F. 1997. Behavior, vocalizations, and relationships of some Myrmotherula Antwrens (Thamnophilidae) in eastern Brazil, with comments on the "plain-winged" group. Ornithological Monographs 48: 809-819.

Willis, E. O.; Oniki, Y. 1992. A new Phylloscartes (Tyrannidae) from southeastern Brazil. Bulletin of the British Ornithologists' Club 112: 158-165.

Further web sources of information
Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Butchart, S., Gilroy, J.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2016) Species factsheet: Myrmotherula unicolor. Downloaded from on 25/10/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from on 25/10/2016.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Alagoas antwren (Myrmotherula snowi) 0

Key facts
Current IUCN Red List category Near Threatened
Family Thamnophilidae (Antbirds)
Species name author (Ménétries, 1835)
Population size 10000-19999 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 34,300 km2
Country endemic? Yes
Links to further information
- Additional Information on this species