Justification of Red List Category
This species is listed as Vulnerable because it has a small population, which is likely to be undergoing a continuous and rapid decline owing to habitat loss and degradation.
The species is rare and local. The majority of the population is found breeding in Flor de Oro in Noel Kempff Mercado National Park, Santa Cruz, Bolivia. Breeding and several flocks of up to 60-70 birds have been recorded in October-December and several hundred have been estimated in late May, but very few individuals have been found in July-October (S. Davis in litt. 1995, 1999). A population of around six pairs rearing 6-10 juveniles per year occurs near San Ignacio de Velasco, Santa Cruz, in the wet season (S. Davis in litt. 1995, 1999). East of Vila Bela da Santíssima Trindade, Mato Grosso, 55 presumably breeding birds were counted in January 1988 (Willis and Oniki 1990), at least 100 non-breeding condition birds were present in July 1997 (L. F. Silveira in litt. 1999), 100-200 in August 2007, and 100 in June 2008 (Kirwan and Areta 2009).
A local density of 2 individuals/km2 was estimated at Los Fierros, Noel Kempff Mercado, Bolivia, from numbers of adult males seen in August-September (Pearce-Higgins 1996). An extrapolation of this density to the occupied area in Brazil led to a national population estimate of 5,480 mature individuals (ICMBio 2018). Brazil comprises roughly half of the global range. The majority of the population in Brazil appears to be resident birds and non-breeding visitors from Bolivia; consequently, to account for migratory individuals, the global population is assessed as substantially less than double the population in Brazil. It is here tentatively placed in the band 2,500-9,999 mature individuals (see also Willis and Oniki 1990; S. Davis in litt. 1995, 1999; Pearce-Higgins 1996; L. F. Silveira in litt. 1999).The subpopulation structure has not been investigated, but due to its migratory nature the species is tentatively assessed as forming one subpopulation (see also ICMBio 2018).
Extensive tracts of the species's habitat are converted rapidly for agriculture. Its preference for seasonally flooded grassland with scattered bushes and trees and avoidance of converted and disturbed areas make it highly susceptible to the clearance and conversion of these habitats, and therefore the species is inferred to undergo a continuing decline (Ergueta and de Morales 1996; ICMBio 2018; Jaramillo and Sharpe 2020). The rate of decline has not been quantified, but it is unlikely to exceed 20% over ten years.
Sporophila nigrorufa is currently known from nine sites in east Bolivia (Santa Cruz) and five in adjacent west-central Brazil (Mato Grosso and Mato Grosso do Sul) (Willis and Oniki 1990; S. Davis in litt. 1995, 1999; Vidoz et al. 2010; Severo-Neto et al. 2015). Small numbers of Sporophila sp. at three additional sites in Mato Grosso probably refer to austral winter records of this species (Willis and Oniki 1990). The major breeding site is Flor de Oro in Noel Kempff Mercado National Park, Santa Cruz, Bolivia. There is an undocumented record of a bird seen in 2005 in Bolivia's Otuquis National Park from a boat on the río Negro (Bolivia/Paraguay border). If this record can be confirmed it may indicate that the species occurs across the river in the Río Negro National Park, Paraguay, although further surveys along the río Negro have failed to find the species (H. del Castillo and R. Clay in litt. 2007; H. del Castillo in litt. 2012).
The species breeds during the austral summer/wet season in seasonally flooded grassland with scattered bushes and trees, which are frequently clumped on decomposing termite mounds. The diet consists primarily of grass seeds. It may be nomadic and/or migratory since it seems to occur in some areas only in the dry season (Willis and Oniki 1990; S. Davis in litt. 1995, 1999). Birds recorded near Concepción, Santa Cruz, were thought to be on passage (Davis 1993).
The effects of extensive and continuing conversion of grassland habitats to agriculture are intensified by its possibly nomadic and/or migratory behaviour. Satellite images reveal that large areas in west Mato Grosso have been converted to agriculture (Killeen and Schulenberg 1998). Breeding sites are presumably affected by cattle-grazing and trampling (S. Davis in litt. 1995, 1999). Trapping for the cagebird trade may be an additional threat (ICMBio 2018).
Conservation Actions Underway
It occurs in Noel Kempff Mercado (Bolivia), Otuquis National Park (Bolivia) and Pantanal Matogrossense (Brazil) National Parks. In 1997, Noel Kempff Mercado was expanded westward and now protects more suitable habitat where the species may occur. Domestic animals have been removed from Flor de Oro (S. Davis in litt. 1995, 1999).
10 cm. Contrasting black and red seedeater. Male has black crown, hindneck and mantle, contrasting with cinnamon-rufous underparts. Paler on cheeks. Large black bill. Female has larger bill than other red Sporophila spp. Similar spp. Other red Sporophila spp. lack black on upperparts and have smaller bills. Voice Simple series of 4-6, high-pitched, whistled notes. Hints Males defend small territories by singing from small trees in clumps of vegetation.
Text account compilers
Clay, R.P., Davis, S., Pilgrim, J., Pople, R., Sharpe, C.J., Silveira, L.F., Stuart, T., Symes, A., Williams, R. & del Castillo, H.
BirdLife International (2023) Species factsheet: Sporophila nigrorufa. Downloaded from http://datazone.birdlife.org/species/factsheet/black-and-tawny-seedeater-sporophila-nigrorufa on 07/06/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 07/06/2023.