About Elaenia mesoleuca (Deppe, 1830)
The olivaceous elaenia, Elaenia mesoleuca, measures 14 to 16 cm (5.5 to 6.3 in) in length and weighs 16 to 20 g (0.56 to 0.71 oz). It is a small elaenia that lacks a crest. Both sexes have identical plumage. Adult individuals have a dull olive crown, with little to no white marking in the center of the crown. They have a distinct white eyering. Their upperparts are dull olive, and their wings are dusky, with yellowish or white tips on the wing coverts that form two visible wing bars. The flight feathers have narrow whitish edges, and the tail is dusky. Their throat is dull gray, their breast has an olive, vest-like pattern, their belly is white, and their flanks and undertail coverts are whitish with a subtle yellow wash. Both sexes have a brown iris, a black bill with a dusky pinkish base to the lower mandible, and black legs and feet.
The olivaceous elaenia is distributed from southern Goiás and southern Bahia in eastern Brazil, extending south through eastern Paraguay into eastern Uruguay and the Formosa, Chaco, and Misiones provinces of northern Argentina. The first recorded observation of this species in Uruguay was in 2000. It inhabits the interior, edges, and clearings of humid tropical forest, and also occurs in gallery forest, secondary forest, and more open woodlands. Its elevational range extends from sea level up to 2,000 m (6,600 ft).
