Argentina (B), Brazil (B) (NB), Paraguay (B) (NB) (P), Uruguay (B).
Breeds in north-eastern Argentina (Corrientes and Entre Ríos), extreme south-eastern Paraguay (Itapúa), extreme south-eastern Brazil (western and south-central Rio Grande do Sul) and western and south-eastern Uruguay (mostly Paysandú, Río Negro and Rocha, also Artigas, Soriano and Treinta y Tres). Migrates northern as far as south-central Brazil (Goiás, south-eastern Mato Grosso and western Minas Gerais).
 
Population
Estimated population is 2,500 - 9,999 (2010) and decreasing.
Chestnut Seedeater (Sporophila) [XC49694]
by Rosendo Fraga from Cerca de San Javier, Rio Negro, Uruguay (song)
Chestnut Seedeater (Sporophila cinnamomea) [XC355718]
by GABRIEL LEITE from \u00c1gua Clara, Mato Grosso do Sul, Brazil (call)
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). A molecular-genetic study of 17 species in genus, including ten in "capped" group ("capuchinos"), indicated that latter form two clades, a northern clade largely north of R Amazon containing Ruddy-breasted Seedeater (Sporophila minuta) and Chestnut-bellied Seedeater (Sporophila castaneiventris), and a southern clade consisting of present species and Copper Seedeater (Sporophila bouvreuil), Tawny-bellied Seedeater (Sporophila hypoxantha), Rufous-rumped Seedeater (Sporophila hypochroma), Dark-throated Seedeater (Sporophila ruficollis), Marsh Seedeater (Sporophila palustris) and Black-bellied Seedeater (Sporophila melanogaster). Determination of relationships within the southern clade not possible, as genetic differentiation very low and species are apparently part of a very recent and rapid radiation. Form described as Narosky's Seedeater (Sporophila zelichi) (from Entre Ríos, in north-eastern Argentina) considered to be a white-necked morph of Marsh Seedeater (Sporophila palustris) or possibly a hybrid between latter and present species.
Similar Species
Rufous-rumped Seedeater (Sporophila hypochroma) has grey back. Nominate Copper Seedeater (Sporophila bouvreuil) has black cap and is more tawny coloured.
References
See References.