Justification of Red List Category
The destruction of this species's habitat is exacerbated by its nomadism and dependence on bamboo flowerings (Collar et al. 1992). The population is now likely to be small and rapidly declining, qualifying it as Vulnerable.
The population is estimated to number 2,500-9,999 mature individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 3,750-14,999 individuals in total, rounded here to 3,500-15,000 individuals.
A rapid and on-going population decline is suspected owing to rates of habitat loss and capture for the wild bird trade.
Sporophila falcirostris is rare in the Atlantic forest of south-east Brazil, east Paraguay and north-east Argentina. In Brazil, recent records are concentrated in Rio de Janeiro and São Paulo, with others in Bahia (Silveira et al. 2005, A. C. De Luca and P. Develey in litt. 2007]), Espírito Santo (1940, 2003-2004 [Simon 2004] and undated), Minas Gerais (specimen from 1936), and Paraná (2001-2004 [Carrano et al. 2004] and a specimen from 1930). In Argentina, recent records come from Misiones: río Iguazú, río Paraná (Areta et al. 2009, in review, Krauczuk and Castía 2009, Bodrati et al. in press) and the Yaboty Biosphere Reserve (La Grotteria and Alvarado 2012). The Paraguayan records are from Salto do Guaíra (1977) and Mbaracayú (1995) in Canindeyú, and Caaguazú in Caazapá (1995) (Madroño and Esquivel 1995, Lowen et al. 1996). It has been considered locally common, with recent records in Argentina of hundreds of individuals during mast seeding of Guadua chacoensis bamboo (A. Bodrati in litt. 2012; Areta et al. in review). It is much rarer than the sympatric Buffy-fronted Seedeater S. frontalis (L. F. Silveira in litt. 2012).
This nomadic bamboo specialist occurs mainly in the middle and higher strata of secondary or disturbed forest, forest borders and urban areas (Areta et al. 2009, A. Bodrati in litt. 2012). It has been observed in Chusquea and Guadua bamboo, and records in Argentina coincide with Guadua masting events (Areta et al. 2009). It feeds primarily on bamboo seeds, turning to the seeds of other species and insects when the former are not available (Areta et al. 2009). In Argentina nesting occurred at the peak of the recent Guadua chacoensis bamboo masting event, in G. chacoensis stands with seeds (Areta et al. in review, A. Bodrati in litt. 2012). By the end of the masting event, there were many females feeding juveniles, and groups of juveniles feeding on the remaining bamboo seeds (Areta et al. 2009, A. Bodrati in litt. 2012).
Over 90% of this species's Atlantic forest habitat has been lost (Areta et al. 2013). Rapid and continuing forest clearance has extended the intervals between major bamboo flowerings and nestings, and its nomadic habits suggest that existing reserves may afford inadequate protection (Areta et al. 2013). It is relatively scarce in trade, but this is almost certainly a reflection of its rarity rather than a lack of demand.
Conservation Actions Underway
This species is considered Vulnerable at the national level in Brazil (Silveira and Straube 2008, MMA 2014), and protected under Brazilian law. It has occurred in Una and Tinguá Biological Reserves; Desengano, Serra do Mar, Ilha do Cardoso, Jacupiranga, Curucutu, Intervales, Cantareira, Ilha Bela, Pico Marumbi and Graciosa State Parks; Itatiaia National Park; Juréia-Itatins and Guaraguaçu Ecological Stations, Ubatuba Experimental Station and Serra Bonita private reserve, Bahia (Wege and Long 1995, E. Machado in litt. 2007, L. F. Silveira in litt. 2012). In Paraguay, it has occurred in Mbaracayú Forest Nature Reserve (Madroño and Esquivel 1995) and Caaguazú National Park (Lowen et al. 1996) and, in Argentina, Iguazú National Park.
11 cm. Mostly grey seedeater. Male pale bluish-grey, whiter towards lower abdomen. Buffy-brown undertail-coverts. Distinctive all-yellow bill with high, curved maxilla and large mandible. White patch at base of primaries. Females similar but dusky brown and with dark bill. Similar spp. Male Uniform Finch Haplospiza unicolor has small, dark bill. Male Plumbeous Seedeater S. plumbea has white chin, dark bill and more prominent wing markings. Voice Very high-pitched, buzzy trill followed by single notes.
Text account compilers
Sharpe, C.J., Symes, A., Capper, D., Pople, R., Williams, R.
Silveira, L.F., De Luca, A., Machado, É., Develey, P., Bodrati, A., Cockle, K.
BirdLife International (2021) Species factsheet: Sporophila falcirostris. Downloaded from http://www.birdlife.org on 20/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 20/10/2021.