Justification of Red List Category
This species is listed as Vulnerable because it has a small population, that is likely to be undergoing a continuous and rapid decline owing to habitat loss and degradation.
The population estimate of 1,000-2,499 individuals is derived from Willis & Oniki (1990), Pearce-Higgins (1996), S. Davis in litt. (1995, 1999), and L. F. Silveira in litt. (1999). This equates to 667-1,666 mature individuals, rounded here to 600-1,700 mature individuals.
This species's population is suspected to be decreasing rapidly, in line with extensive and continuing conversion of grassland habitats to agriculture.
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. 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 local density of two birds per km2 was estimated at Los Fierros, Neol Kempff Mercado, based on numbers of adult males seen in August-September (Pearce-Higgins 1996). 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). 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).
It 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) and 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).
Conservation Actions Underway
It occurs in Noel Kempff Mercado (three sites, 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
Pilgrim, J., Pople, R., Sharpe, C J, Stuart, T., Symes, A., Williams, R.
del Castillo, H., Machado, É., Silveira, L., Davis, S., Clay, R.P.
BirdLife International (2021) Species factsheet: Sporophila nigrorufa. Downloaded from http://www.birdlife.org on 16/09/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 16/09/2021.