Similar morphologically to the decidedly rarer but partially sympatric Rufous-rumped Seedeater (Sporophila hypochroma), the Tawny-bellied Seedeater is also rather more widespread. It is found in native grassland, including alongside roads and in marshes, from northern and eastern Bolivia to southern Brazil, and south across Paraguay to northern Argentina. Males are primarily brownish gray over the upperparts, with a white wing speculum, while the rump and underparts are tawny rufous, becoming paler over the face. Females, in contrast but like those of many other Sporophila, are difficult to identify, being mainly brown above and buffy brown below. Especially during the non-breeding season, this species is frequently found in mixed-species flocks, e.g. in rice fields, with other open-country Sporophila, which can be hundreds of individuals strong.