Pearly-bellied Seedeater

The pearly-bellied seedeater is about 10 cm (3.9 in) long and weighs 7.6 to 10 g (0.27 to 0.35 oz). It is one of the smallest of its genus. It has a short, thick bill with a rounded culmen. The species is sexually dimorphic. Adult males have a black cap down to the eye. Their face is off-white and their nape grayish pink. Their upperparts are mostly grayish pink with grayish brown uppertail coverts and a blackish tail. Their wings are blackish with very pale cinnamon-brown edges on the coverts and tertials. Their wing's primaries have white bases that show as a white rectangle on the folded wing. Their thighs are black. Females have an olive-brown head and upperparts. Their wings and tail are a slightly darker olive-brown with a small white primary patch on the former. Their throat and underparts are mostly ochre-buff with a whitish belly. Both sexes have a dark brown iris, a blackish bill, and blackish legs. Juveniles resemble adult females.

The pearly-bellied seedeater is found in Brazil south of a line roughly from northwestern Mato Grosso do Sul east to southeastern Goías and then south to the Atlantic in east-central São Paulo state; its southern extent in the country is northern Rio Grande do Sul and Santa Catarina. Its range continues west and south into eastern Paraguay, northeastern Argentina's Misiones and Corrientes provinces, and far northern Uruguay. Though one source includes Bolivia in the species' range others do not and the South American Classification Committee (SACC) has only unconfirmed records there. The pearly-bellied seedeater inhabits open Cerrado, the ecotone between Cerrado and Atlantic Forest, savanna, and grasslands including the humid chaco. In elevation it ranges from sea level to 1,100 m (3,600 ft) in Brazil and to at least 1,200 m (3,900 ft) elsewhere.

The pearly-bellied seedeater feeds on grass seeds. It typically feeds while clinging to stems but it will feed on the ground. During the breeding season it usually forages in pairs and at other times it forages in groups that include other seed-eating species and can be quite large.