Eastern Bolivia (eastern Santa Cruz; recently also Llanos de Moxos, in north-eastern Beni) and south-western Brazil (western Mato Grosso).
 
Population
Estimated population is 1,000 - 2,499 (2010) and decreasing.
Status VU
Habitat destruction due to extensive and continuing conversion of grassland to agriculture is the main threat.
For more information see BirdLife International Species Factsheet.
Voice
A simple series of 4-6, high-pitched, whistled notes.
Black-and-tawny Seedeater (Sporophila nigrorufa) [XC66672]
by Jeremy Minns from Vila Bela da Sant\u00edssima Trindade, MG. Fazenda Boa Esperan\u00e7a, Brazil (song)
Black-and-tawny Seedeater (Sporophila nigrorufa) [XC602754]
by Sjoerd Mayer from Vila Bela da Sant\u00edssima Trindade, State of Mato Grosso, Brazil (call, song)
Subspecies
No subspecies.
Molecular evidence suggests that genus is closely related to Oryzoborus, which should perhaps be subsumed within it. Further, that both genera should be placed in the tanager family (Thraupidae). This species presumed most closely related to Capped Seedeater (Sporophila bouvreuil), and part of the southern clade of "capped" seedeaters (Capped Seedeater (Sporophila bouvreuil), Tawny-bellied Seedeater (Sporophila hypoxantha), Grey-and-chestnut Seedeater (Sporophila hypochroma), Dark-throated Seedeater (Sporophila ruficollis), Marsh Seedeater (Sporophila palustris), Chestnut Seedeater (Sporophila cinnamomea), Black-bellied Seedeater (Sporophila melanogaster)).