Data Zone
Justification of Red List category
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (extent of occurrence <20,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Population justification
The global population size has not been quantified, but the species is described as uncommon to locally fairly common, though probably overlooked (Stotz et al. 1996). Suitable habitat is patchily distributed, so that the species may only locally reach relatively high densities (B. Phalan in litt. 2022).
Trend justification
A slow decline is suspected to be occurring, owing to on-going drainage and conversion of wetland habitats. The rate of decline has not been quantified.
Spartonoica maluroides occurs in extreme south Brazil (Paraná and Rio Grande do Sul), Uruguay and central Argentina, ranging to southern Paraguay.
This species occurs in sedges and reedbeds in brackish, salt 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, Llambías 2020). In Brazil, it was found to strongly rely on coastal salt marshes for breeding (G. N. Mauricio in litt. 2022). Its movements are not well known, but it is possible that individuals undertake short-distance seasonal movements, as evidenced by seasonal changes in abundance (Llambías 2020). The species feeds on invertebrates. The breeding season lasts from September to February; the nest is made of twigs and grasses and placed close to the ground inside vegetation (Llambías 2020).
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). A further threat is overgrazing of grasslands by cattle and the establishment of wind farms (Llambías 2020, P. G. Fernández in litt. 2022, G. N. Mauricio in litt. 2022).
Conservation Actions Underway
No targeted actions are known. The species is listed as Vulnerable at the national level in Argentina (MAyDS and AA 2017).
Conservation Actions Proposed
Carry out surveys to quantify the population size and population trend. Investigate the species' movement ecology and subpopulation structure. Monitor the population trend. Monitor rates of habitat loss and degradation within its range. Protect suitable wetland habitats within the range.
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-throated Spinetail Cranioleuca sulphurifera 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.
Text account compilers
Hermes, C.
Contributors
Butchart, S., Chebez, J.C., Fernández, P., Gilroy, J., Jaramillo, A.P., Mauricio, G., Phalan, B. & Sharpe, C.J.
Recommended citation
BirdLife International (2024) Species factsheet: Bay-capped Wren-spinetail Spartonoica maluroides. Downloaded from
https://datazone.birdlife.org/species/factsheet/bay-capped-wren-spinetail-spartonoica-maluroides on 22/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/12/2024.