Justification of Red List Category
This species is listed as Endangered because it has a very small and severely fragmented range that is likely to be declining rapidly in response to habitat loss (Collar et al. 1992). It is known from just seven sites.
The population is estimated to number 1,000-2,499 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 667-1,666 mature individuals, rounded here to 600-1,700 mature individuals.
An ongoing rapid population decline is suspected to be taking place owing to rates of habitat loss.
Formicivora erythronotos survives in a narrow coastal strip around the Baía da Ilha Grande in south Rio de Janeiro, Brazil. Although known from c.20 specimens collected in the 19th century, it was unrecorded for over 100 years until its rediscovery in 1987. It has been subsequently found at a further seven sites (Buzzetti 1998, E. Mendonça and L. P. Gonzaga in litt. 2000). The main localities are Ariró (densities of 89 pairs/km2) and Vale do Mambucaba (156 pairs/km2) (Mendonça and Gonzaga 1999b). Smaller numbers have also been recorded at Bracuí, Frade, São Gonçalo, Taquari and Barra Grande (Buzzetti 1998, Mendonça and Gonzaga 1999b, E. Mendonça and L. P. Gonzaga in litt. 2000).
It was rediscovered in a swampy patch of secondary forest near the forest-mangrove ecotone. Subsequent records have found the species to occur mostly in the lush understorey of modified restinga, early successional habitats such as second growth and the understorey of old second growth (Mendonça and Gonzaga 1998, Mendonça and Gonzaga 1999b), and sometimes abandoned banana plantations (E. Mendonça and L. P. Gonzaga in litt. 2000). These areas are dominated by pioneer species, including Lantana camara, Cecropia sp., Morus sp., Rubus, Vernonia sp. and grasses (Mendonça and Gonzaga 1999b). It has once successfully colonised fields two months after burning, where there was little regenerating vegetation (Mendonça and Gonzaga 1999b, Mendonça and Gonzaga 1999a). Nests have been found in second growth from mid-August to early February, with eggs producing an average of 0.23 young (Mendonça and Gonzaga 1999a).
It cannot tolerate many of the human activities occurring within its range. Development of the narrow coastal plain for tourism and beachside housing has been extensive and threatens the small remnant patches of suitable habitat, especially at Fazenda Ariró where there are plans for a large hotel complex (Mendonça and Gonzaga 1999b, E. Mendonça and L. P. Gonzaga in litt. 2000). There is widespread clearance of Euterpe sp. palms for pasture and plantations, both of which provide unsuitable habitat for this species (Mendonça and Gonzaga 1999b). Such plantations have reduced available habitat in the Vale do Mambucaba (E. Mendonça and L. P. Gonzaga in litt. 2000).
Conservation Actions Underway
It is protected under Brazilian law and occurs in the buffer-zone of the Serra da Bocaína National Park. Formerly considered Endangered at the national level (Silveira & Straube 2008), it is now designated as Critically Endangered under Brazilian law (MMA 2014). It may occur in Tamoios Environmental Protection Area, but the limits of this reserve are unclear on the ground (Mendonça and Gonzaga 1999a).
11.5 cm. Distinctive, black-and-rufous antwren. Male slaty-black with rufous-chestnut back. Black wings with three narrow, whitish wing-bars. White flanks often concealed. Slender black bill. Female similar to male but slaty-black replaced by olivaceous-brown, becoming more buffy on underparts. Voice Song is three-second series of low-pitched tchóup calls. Also high-pitched tcheek calls and soft churrs.
Text account compilers
Clay, R., Pople, R., Sharpe, C J, Symes, A., Williams, R.
Mendonça, E., Gonzaga, M.
BirdLife International (2020) Species factsheet: Formicivora erythronotos. Downloaded from http://www.birdlife.org on 07/08/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 07/08/2020.