Fairly common throughout the Amazonian lowlands, Chestnut-bellied Seed-Finch inhabits woodlots, forest edges, and clearings. There, they forage for grass seeds low in shrubbery or on the ground. They are usually encountered singly or in pairs. Their song is a fast series of melodious whistled notes and trills. Very closely related to Thick-billed Seed-Finch, these two species have been lumped in the past under the name “Lesser Seed-Finch.” Although mostly separated by range, with Thick-billed occurring farther north and west than Chestnut-bellied, these species do hybridize where they overlap. However, whereas male Thick-billed Seed-Finches are solidly black overall, Chestnut-bellieds can be distinguished by their dark brown belly and undertail coverts.