Justification of Red List Category
This species has a small range and population occurring at a few isolated locations. Virtually no habitat remains outside of the reserves in which it occurs, and most of these are not effectively protected. Fragmentation and continuing habitat loss are so extensive within its range that the suspected rapid population decline qualifies it as Vulnerable.
The population is estimated to number 2,500-9,999 mature individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 3,750-14,999 individuals, rounded here to 3,500-15,000 individuals.
This species's population is suspected to be declining rapidly, in line with rates of habitat loss within its range.
Myrmotherula minor occurs in south-east Brazil, with most recent records in the Serra da Bocaina and Serra do Mar in south Rio de Janeiro and São Paulo. There are also records from Minas Gerais (one site), Espírito Santo and north-east Santa Catarina (one old specimen and one recent record [Naka et al. 2000]), with possible records from Bahia. Although it has been listed for north-east Peru, until there is some undisputed evidence of its occurrence outside the Atlantic forest region, M. minor must be considered restricted to south-east Brazil. Its current range is highly fragmented and it is now rare, with recent records from only a small number of localities (Whitney and Pacheco 1995).
It inhabits the interior of undisturbed and old second growth forest in humid regions where trees are festooned with mosses, bromeliads and other epiphytic growth. Second growth is only tolerated if adjacent to essentially mature forest. It is almost always found near water, either in swampy forest, or close to fast-flowing streams (Whitney and Pacheco 1995). Individuals are rarely observed away from mixed-species flocks (Aleixo and Galetti 1997, Whitney and Pacheco 1997, J. F. Pacheco in litt. 1999, L. F. Silveira in litt. 1999) and forage from ground-level to 12 m, although generally in the range 2-8 m (Whitney and Pacheco 1997). Three pairs in lowland forest at the Juréia-Itatins Ecological Station had home ranges of 2.2 ha, 3 ha and 5.8 ha (Develey 1997). Most recent records have been below 300 m (Whitney and Pacheco 1995), although it regularly occurs at 800 m in the Augusto Ruschi Biological Reserve (E. O. Willis and Y. Oniki in litt. 1999).
Virtually all lowland Atlantic forest outside protected areas has been deforested within its historical range, and even some of the protected areas in which it occurs are not secure (Whitney and Pacheco 1995). There is almost no suitable habitat remaining in Espírito Santo below 700 m, and 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 forest below the base of the slopes cleared or heavily degraded (Whitney and Pacheco 1995).
Conservation Actions Underway
This species is officially listed as Vulnerable at the national level in Brazil (Silveira and Straube 2008, MMA 2014). In Rio de Janeiro, it occurs in Poço das Antas and Tinguá Biological Reserves. The unprotected Fazenda União (J. F. Pacheco in litt. 1999) is the only site where it occurs with Band-tailed Antwren M. urosticta and Unicolored Antwren M. unicolor. In São Paulo, most remaining forest in Serra da Bocaina National Park is at inappropriate altitudes, and Serra do Mar State Park is not adequately protected (Whitney and Pacheco 1995). It also occurs in Juréia-Itatins Ecological Station (Develey 1997, L. F. Silveira in litt. 1999) and Jurupará State Park (Develey 1997), São Paulo, and Augusto Ruschi Biological Reserve, Espírito Santo (E. O. Willis and Y. Oniki in litt. 1999).
9 cm. Small, grey, black and white antwren. Male grey, with black bib extending to mid-chest. Undertail-coverts barred black and white, wings black with white-tipped coverts. Tail with narrow black subterminal band, rectrices fringed white. Female has ashy crown grading into brownish-olive back, dusky wings with olivaceous-buff tipped coverts. Rectrices fringed russet, olivaceous-buff underparts and whitish on throat. Similar spp. No other Myrmotherula has barred undertail-coverts. Male White-flanked Antwren M. axillaris luctuosa has silvery-grey flanks and more extensive black bib, female has contrastingly paler flanks. Both sexes of Band-tailed Antwren M. urosticta have broad, white tail tip. Voice Distinctive, two or three, multi-syllabic whistles.
Text account compilers
Capper, D., Clay, R., Pople, R., Sharpe, C J, Symes, A., Williams, R.
Willis, E., Develey, P., De Luca, A., Silveira, L., Oniki, Y., Pacheco, J.
BirdLife International (2021) Species factsheet: Myrmotherula minor. Downloaded from http://www.birdlife.org on 23/04/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/04/2021.