Unicolored Antwren Myrmotherula unicolor


Justification of Red List Category
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.

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.

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).


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

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).


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.


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

Recommended citation
BirdLife International (2022) Species factsheet: Myrmotherula unicolor. Downloaded from http://www.birdlife.org on 08/08/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 08/08/2022.