About Ramphotrigon megacephalum (Swainson, 1835)
The large-headed flatbill (scientific name Ramphotrigon megacephalum (Swainson, 1835)) is 12.5 to 13.2 cm (4.9 to 5.2 in) long and weighs 13 to 15 g (0.46 to 0.53 oz). Both sexes share identical plumage. Adults of the nominate subspecies R. m. megacephalum have a dark olive crown, dusky lores, a whitish to yellowish streak behind the lores, and a whitish to yellowish eye-ring on an otherwise dark olive face. Their upperparts are dark olive. Their wings are mostly dusky, with yellow-olive edges on the flight feathers and ochraceous tips on the coverts; the ochraceous tips form two distinct wing bars. Their tail is dusky with yellow-olive edges along the feathers. Their throat is whitish to yellowish, their breast is grayish olive with faint yellowish streaks, and their belly is yellow. Subspecies R. m. pectorale has a browner breast and more extensive yellow on the belly than the nominate subspecies. R. m. venezuelense is darker than the nominate and has cinnamon edges on its wing feathers. R. m. bolivianum has a dusky greenish crown, a browner breast, and a duller yellow belly than the nominate. All subspecies have a brown iris, a flat black bill with a dull pinkish base to the mandible, and gray legs and feet. The large-headed flatbill has a highly disjunct distribution, with each subspecies occurring separately from all others, with ranges detailed below. The northernmost subspecies is R. m. venezuelense. It occurs discontinuously in Venezuela, in western Trujillo, western Apure, western Barinas, northeastern Yaracuy, and the coastal range in northern Aragua. Its range extends slightly west into northern Colombia, and records from Guyana and Suriname are believed to belong to this subspecies. R. m. pectorale also occurs in Venezuela, with an isolated population in southern Amazonas. Its main range extends along the eastern side of the Colombian Andes and across south-central Colombia. It also occurs locally on the east side of the Andes in Ecuador, extends slightly into far northwestern Brazil, and possibly occurs in extreme northern Peru. R. m. bolivianum is found in eastern Peru from Ucayali Department south into northern Puno Department, east into Brazil as far as Pará and Mato Grosso, and south into northern Bolivia to the northern departments of Cochabamba and Santa Cruz. R. m. megacephalum occurs from Espírito Santo and eastern Minas Gerais in southeastern Brazil, extending southwest into southeastern Paraguay and the Misiones Province of northeastern Argentina. The large-headed flatbill inhabits seasonally flooded várzea and igapó forest, where it is found almost exclusively in and near stands of native bamboo. In northern Venezuela, it also occurs in plantations of introduced Asian bamboo. Its maximum elevation reaches 600 m (2,000 ft) in northern Venezuela, about 540 m (1,800 ft) in Amazonas, 500 m (1,600 ft) in Colombia, 1,200 m (3,900 ft) in Peru, and between 300 and 1,300 m (1,000 and 4,300 ft) in Ecuador.
