Eastern Olivaceous Flatbill

The eastern olivaceous flatbill is about 15 cm (5.9 in) long and weighs 18 to 24.8 g (0.63 to 0.87 oz). The sexes have the same plumage. Adults of the nominate subspecies have a dark olive head with a white eye-ring. Their entire upperparts are dark olive. Their wings are dusky with ochre to buff edges on the wing coverts and secondaries that form two dull wing bars. Their tertials have yellow edges. Their tail is a dusky with paler outer edges on the feathers. Their throat is pale gray to pale yellow, their breast grayish olive, and their belly, flanks, and vent are pale yellow. The breast and flanks have olive streaks. Juveniles have duller olive upperparts, paler yellow underparts, and more ochraceous olive uppertail coverts than adults. The other two subspecies have essentially the same plumage though R. o. guianensis has a fainter eye-ring than the nominate. All subspecies have a dark brown iris, a wide flat bill with a black maxilla and a pale horn mandible, and blue-gray to gray legs and feet.

The eastern olivaceous flatbill has a disjunct distribution. Subspecies R. o. guianensis is found from Bolívar and eastern Amazonas states in Venezuela east through the Guianas and northern Brazil north of the Amazon from the Negro River east to the Atlantic. Subspecies R. o. sordidus is found across Brazil south of the Amazon from the Tapajós River east to the Tocantins River and the Atlantic in northern Maranhão state. The nominate subspecies is found separately in northeastern and eastern Brazil between Pernambuco and Rio de Janeiro states. The species primarily inhabits humid terra firme forest and secondary woodland, and also várzea forest. In elevation it ranges from sea level to 500 m (1,600 ft).

The eastern olivaceous flatbill feeds on arthropods, though details are lacking. It typically forages singly and often joins mixed-species feeding flocks. It tends to be sluggish, peering slowly around and up from a perch in the understory. It captures prey in the understory to mid-story, using outward or upward sallies to snatch or hover-glean it from leaves and twigs. It only rarely takes prey in mid-air. It typically lands on a different perch after a sally.