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Parana Antwren Stymphalornis acutirostris
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This recently described species is Endangered because it has a very small and severely fragmented range, which is declining in response to habitat loss.

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

13.5 cm. Medium-sized but slender antwren. The male is dark chocolate brown above and dark plumbeous below. Some have a faint white mottling on chin and malar. Dusky wings. Black wing-coverts fringed white. Blackish tail with small white tips to feathers. No whitish flank plumes. Females are paler brown above, greyer and speckled around the face. Whitish underparts, coarsely streaked blackish. Wings and tail as in the male, but browner. Voice Both sexes deliver constant whistled and repeated piu-píc or píc-piu nasal notes, and both also deliver nhééé calls and soft pic contact calls.

Distribution and population
Stymphalornis acutirostris is known in a discrete area in coastal Paraná, Santa Catarina and Sao Paulo, southern Brazil. It was found in 1995 in a small marsh near Matinhos city, southern Paraná coast (Bornschein et al. 1995). Subsequent surveys have found the species at Antonina, Morretes, Paranaguá, Pontal do Paraná and Guaratuba municipalities in Paraná state, and at Garuva, Itapoá, Joinville, Araraquari, Balneário Barra do Sul, Guaramirim, São João do Itaperiú and Barra Velha municipalities in Santa Catarina state (Bornschein and Reinert 1997, Reinert 2001, Reinert et al. 2007). The taxonomic position of birds present at the Tiete river mouth, Sao Paulo requires clarification and it has been suggested that they may represent a separate species (Reinert et al. 2007). The stronghold is Guaratuba Bay, where it is known in Ilha do Chapeu, Chapeuzinho and the lower thirds of the rios São João, Cubatão, São Joãozinho, Descoberto, Boguaçu, Preto, Parado and Alegre (Reinert 2001, Reinert et al. 2007), which holds the largest subpopulation (more than 7,000 individuals) (Reinert 2001, Reinert et al. 2007). All populations are restricted to small patches or narrow tracts of habitat (Reinert 2001, Reinert et al. 2007).

Population justification
A total population of 17,700 individuals was estimated by Reinert et al. (2007), and so it is best placed in the band 10,000-19,999 individuals. This equates to 6,667-13,333 mature individuals, rounded here to 6,000-15,000 mature individuals.

Trend justification
A slow and ongoing population decline is suspected, owing to habitat loss and degradation.

It exclusively inhabits littoral marshes, dominated by Scirpus californicus with other marsh vegetation (especially Asteraceae and Poaceae) such as grasses and bushes. It also occurs in riverine marshes, flooded plains with herbaceous vegetation and transition areas to mangrove swamps and flooded lowland florests with herbaceous strata. Most localities are subject to periodic fluctuations in water-levels. It is mostly found in pairs in low, dense vegetation. It forages mostly below 60 cm and the diet appears to consist exclusively of arthropods (Reinert et al. unpubl. data.).

Some patches of habitat, including the type-locality, are under constant human pressure and have been reduced by fires, allotments and landfills. Other threats include land acquisition, disturbance from boat traffic on rivers during the breeding season, erosion due to water traffic, sand extraction from river margins, invasive vegetation (especially Brachiaria spp.) and cattle-grazing (Bornschein et al. 1995, Bornschein and Reinert 1997, Reinert 2001, Reinert et al. 2007, Reinert et al. unpubl. data.). The species also could be affected by sea level rise, which could greatly reduce the area of suitable habitat (Reinert et al. unpubl. data.).

Conservation Actions Underway
Proposals for action have been put to governmental agencies but no action has yet been taken (Bornschein and Reinert 1997, Reinert 2001, Reinert et al. 2007, Reinert et al. unpubl. data.). Conservation Actions Proposed
Protect key sites, especially in Guaratuba Bay (Bencke et al. 2006, Reinert et al. 2007). Conduct long-term population monitoring to ascertain trends. Clarify taxonomic status of Sao Paulo birds.

Bencke, G. A.; Mauricio, G.N.; Develey, P. F.; Goerck, J.M. 2006. Áreas importantes para a conservação das aves no Brasil, parte I: estados do Domínio da Mata Atlântica inclui áreas de Carrado, Caatinga e Pampas. SAVE Brasil, Sao Paulo.

Bornschein, M. R.; Reinert, B. L. 1997. Novas informaçãoes sobre a distribuição e habitat de Stymphalornis acutirostris (Formicariidae). Resumos VI Congresso Brasiliero de Ornitologia, Belo Horizonte, 24-28 February 1997, pp. 20.

Bornschein, M. R.; Reinert, B. L.; Teixeira, D. M. 1995. Um novo formicariidae do sul do Brasil (Aves, Passeriformes).

Gonzaga, L. P. 2001. Análise Filogenética do Gênero Formicivora Swainson 1825 (Aves: Passeriformes: Thamnophilidae) Baseada em Caracteres Morfológicos e Vocais. PhD, Universidade Federal do Rio de Janeiro.

IUCN. 2015. The IUCN Red List of Threatened Species. Version 2015-4. Available at: (Accessed: 19 November 2015).

Reinert, B. L. 2001. Universidade Federal do Paraná., Dissertação de mestrado. Curitiba.

Reinert, B. L., Bornschein, M. R., Firkowski, C. 2007. Distribuição, tamanho populacional, hábitat e conservação do bicudinho-do-brejo Stymphalornis acutirostris Bornschein, Reinert e Teixeira, 1995 (Thamnophilidae ). Revista Brasileira de Ecologia 15(4): 493-519.

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
Pople, R., Sharpe, C J & Symes, A.

Olmos, F. & Reinert, B.

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

Recommended citation
BirdLife International (2016) Species factsheet: Stymphalornis acutirostris. Downloaded from on 27/10/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from on 27/10/2016.

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 - Parana antwren (Stymphalornis acutirostris) 0

Key facts
Current IUCN Red List category Endangered
Family Thamnophilidae (Antbirds)
Species name author Bornschein, Reinert & Teixera, 1995
Population size 6000-15000 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 1,900 km2
Country endemic? Yes
Links to further information
- Additional Information on this species