Black-bellied Seedeater

The black-bellied seedeater is 10 to 10.6 cm (3.9 to 4.2 in) long and weighs 8 to 10.5 g (0.28 to 0.37 oz). It is one of the smallest of its genus. It has a smallish bill with a rounded culmen. The species is sexually dimorphic. Adult males have a mostly bluish gray head and neck with a black throat. Their upperparts are bluish gray and their tail blackish gray. Their wings are blackish gray with white bases on the primaries that show as a patch on the folded wing. Their sides are bluish gray and the rest of their underparts black. Females have an olive-brown head and back. Their tail and wings are a darker olive-brown with the same white primary patch as males. Their underparts are a buffier brown. Both sexes have a brown iris and dark legs. Males have a black or dark gray bill; females have a brownish gray bill with a pale yellowish mandible. Juveniles resemble adult females.

The black-bellied seedeater is found in southeastern Brazil. It ranges from northeastern Rio Grande do Sul north to eastern Mato Grosso do Sul, the southern half of Goías, and the western half of Minas Gerais. It inhabits tall moist grasslands, including marshes, and scrubby areas. In elevation it ranges from near sea level to 1,100 m (3,600 ft). The South American Classification Committee has records of the species as a vagrant in Argentina.

The black-bellied seedeater feeds on grass seeds, especially those of native grasses but also those of exotics, and also includes some small arthropods in its diet. It typically feeds while clinging to stems, sometimes upside down as the stem bends. In the breeding season it forages in pairs or family groups and outside it in larger groups that include other seed-eating species.