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Bay-capped Wren-spinetail Spartonoica maluroides
BirdLife is updating this factsheet for the 2016 Red List
Please email us with any relevant information

This wetland habitat specialist is thought to have a moderately small and severely fragmented population, and is likely to be declining owing to the drainage and degradation of wetlands for agricultural developments. It is therefore considered Near Threatened.

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

Size: 14 cm. Summary: A small streaky, long tailed marsh furnarid. Id: Above, fawn with black streaking and contrasting rufous crown and indistinct white supercillium; wings dusky with cinnamon bases to flight feathers; long pointed tail brown. Underparts whitish becoming buffy on flanks. Similar: Three sympatric species (Hudson's Canastero Asthenes hudsoni, Sulphur-bearded Spinetail Cranioleuca pyrrophia and Grass Wren Cistothorus platensis) also found in marshes are basically similar, though all lack the distinctive rufous crown. Hints: Inconspicuous and hard to see; most often located by voice. Voice: A 2-3 second mechanical reeling trill.

Distribution and population
Spartonoica maluroides occurs in extreme south Brazil (Rio Grande do Sul), Uruguay, and central Argentina (east Formosa, Chaco, Corrientes, Entre Ríos and Buenos Aires west locally to Córdoba, Santiago del Estero and Mendoza, and south to Río Negro) (Ridgely and Tudor 1994, Chebez et al. 1998, J. C. Chebez in litt. 1999). It is an uncommon, but regular winter visitor to Paraguay (R. Clay in litt. 2009). It is uncommon to locally fairly common, but probably overlooked.

Population justification
The global population size has not been quantified, but this species is described as 'fairly common' (Stotz et al. (1996).

Trend justification
A slow decline is suspected to be occurring, owing to on-going drainage and conversion of wetland habitats.

This species occurs up to 900 m in brackish and freshwater marshes with extensive growths of Eryngium and Scirpus, and may associate with Spartina grass (Ridgely and Tudor 1994, Pearman and Abadie 1995, Parker et al. 1996, A. Jaramillo in litt. 1999). Breeding biology is described by Llambías et al. (2009).

This species is limited to wetland habitats, and is therefore highly threatened by marsh drainage and the drying effects of Eucalyptus and Pinus plantations, particularly in east Entre Ríos and north-east Corrientes (Pearman and Abadie 1995).

Conservation Actions Underway
Conservation Actions Proposed
Carry out surveys to assess the species's population size. Monitor rates of habitat loss and degradation within its range. Campaign for the protection of suitable wetland habitats within the range, including the gazetting of protected areas at key sites.

Chebez, J. C.; Rey, N. R.; Barbaskas, M.; Di Giacomo, A. G. 1998. Las aves de los Parques Nacionales de la Argentina. Literature of Latin America, Buenos Aries.

Llambías, P. E.; Ferretti, V.; Cardoni, D.A.; Maldonado, J. E. 2009. Breeding success and social mating system of the Bay-capped Wren-spinetail (Spartonoica maluroides). Wilson Journal of Ornithology 121(4): 803-807.

Parker, T. A.; Stotz, D. F.; Fitzpatrick, J. W. 1996. Ecological and distributional databases. In: Stotz, D.F.; Fitzpatrick, J.W.; Parker, T.A.; Moskovits, D.K. (ed.), Neotropical bird ecology and conservation, pp. 113-436. University of Chicago Press, Chicago.

Pearman, M.; Abadie, E. I. 1995. Mesopotamia grassland and wetlands survey 1991-1993.

Pearman, M.; Abadie, E. I. Undated. Mesopotamia grasslands and wetlands survey, 1991--1993: conservation of threatened birds and habitat in north-east Argentina.

Ridgely, R. S.; Tudor, G. 1994. The birds of South America. University of Texas Press, Austin, Texas.

Stotz, D. F.; Fitzpatrick, J. W.; Parker, T. A.; Moskovits, D. K. 1996. Neotropical birds: ecology and conservation. University of Chicago Press, Chicago.

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
Butchart, S., Gilroy, J., Sharpe, C J

Chebez, J., Jaramillo, A.

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

Recommended citation
BirdLife International (2016) Species factsheet: Spartonoica maluroides. Downloaded from on 23/10/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from on 23/10/2016.

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 - Bay-capped wren-spinetail (Spartonoica maluroides) 0

Key facts
Current IUCN Red List category Near Threatened
Family Furnariidae (Ovenbirds)
Species name author (D'Orbigny & Lafresnaye, 1837)
Population size Unknown mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 1,270,000 km2
Country endemic? No
Links to further information
- Additional Information on this species