Myrmotherula unicolor 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Thamnophilidae

Scientific Name: Myrmotherula unicolor
Species Authority: (Ménétries, 1835)
Common Name(s):
English Unicoloured Antwren, Unicolored Antwren
Taxonomic Source(s): SACC. 2006. A classification of the bird species of South America. Available at: #
Taxonomic Notes: 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).

Identification information: 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.

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Butchart, S., Gilroy, J.
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.

Previously published Red List assessments:
2008 Near Threatened (NT)
2004 Near Threatened (NT)
2000 Vulnerable (VU)
1996 Vulnerable (VU)
1994 Vulnerable (VU)
1988 Not Recognized (NR)

Geographic Range [top]

Range Description: 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).

Countries occurrence:
Continuing decline in area of occupancy (AOO): Yes
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 34300
Continuing decline in extent of occurrence (EOO): Yes
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 11-100
Continuing decline in number of locations: Yes
Extreme fluctuations in the number of locations: No
Upper elevation limit (metres): 500
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: 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.
Current Population Trend: Decreasing
Additional data:
Number of mature individuals: 10000-19999 Continuing decline of mature individuals: Yes
Extreme fluctuations: No Population severely fragmented: Yes
No. of subpopulations: 2-100 Continuing decline in subpopulations: Yes
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: No

Habitat and Ecology [top]

Habitat and Ecology: 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).

Systems: Terrestrial
Continuing decline in area, extent and/or quality of habitat: Yes
Generation Length (years): 5.1
Movement patterns: Not a Migrant

Threats [top]

Major Threat(s): 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 [top]

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).

Citation: BirdLife International. 2012. Myrmotherula unicolor. The IUCN Red List of Threatened Species 2012: e.T22701524A38080952. . Downloaded on 01 December 2015.
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