Wedge-tailed Grass-Finch

The wedge-tailed grass finch is about 20 cm (7.9 in) long and weighs 21 to 37 g (0.74 to 1.3 oz). It has a long pointed tail and a moderately thick bill. The sexes have the same plumage. Adults of the nominate subspecies E. h. herbicola have a pale brownish crown with thin blackish streaks. They have a mostly pale brownish face with paler lores, a pale supercilium, and a faint whitish eye-ring. Their nape is pale browish. Their upperparts are mostly boldly streaked with brown and blackish; their rump is unstreaked and the uppertail coverts' black streaks are thin. Their wings are mostly brownish with wide bright olive-green edges. Their tail feathers have dark centers and grayish brown edges. Their throat is grayish white and their underparts mostly creamy white. Their flanks and vent area are buff. They have a dark brown iris, a yellow to yellow-orange bill with a blackish culmen, and brownish yellow to dull pinkish legs feet. Juveniles are similar to adults with the addition of a rusty yellow cast to the upperparts, a yellow cast to the face and underparts, and streaks on the breast. All of the other subspecies of the wedge-tailed grass finch are smaller than the nominate, have darker faces, and thinner black streaks on the upperparts. Subspecies E. h. lucaris has somewhat rusty upperparts. E. h. …

The wedge-tailed grass finch has a highly disjunct distribution. Only E. h. apurensis and E. h. sphenurus have contiguous ranges, and the latter has many gaps in its range. The subspecies are found thus:

E. h. lucaris: the Térraba region in southwestern Costa Rica E. h. hypochondriacus: western and central Panama E. h. apurensis: lowlands of eastern Colombia from northern Meta Department into western Venezuela's Guárico, Portuguesa, Barinas, and Apure states E. h. sphenurus: locally in Colombian Andes, extreme southern Ecuador, patchily through central Peru, Venezuela except western lowlands and Cerro Duida, the Guianas, and northeastern Brazil from Amapá to northern Maranhão E. h. herbicola: roughly the southern half of Brazil, west into eastern Bolivia, and south through eastern Paraguay into northern Uruguay and northern Argentina as far as northern Entre Ríos and Santa Fe provinces The wedge-tailed grass finch inhabits damp to dryish grasslands that usually have some scattered shrubs. The nominate also inhabits savanna. In all areas it greatly favors tall grass. In elevation it ranges up to 800 m (2,600 ft) in Costa Rica, to 1,800 m (5,900 ft) in Colombia, and to 1,600 m (5,200 ft) in Venezuela. It ranges between 800 and 1,450 m (2,600 and 4,800 ft) in Peru and from sea level to 1,500 m (4,900 ft) in Brazil.

The wedge-tailed grass finch's diet has not been studied but is believed to be mostly seeds and arthropods. Single individuals and pairs forage on the ground, usually in tall grass. They sometimes follow army ant swarms.