Brownish elaenia the Xingu River in the south of Pará state, North Region, Brazil; it ranges upstream on the Xingu for 700 km, then a tributary to the west of the Xingu, the Rio Iriri, for another 700 km. The next upstream tributary for the bird's range, is the Madeira River in the Amazon Basin's southwest, Amazonas state. The range proceeds 2400 km upstream into the headwaters of the Madeira in northern Bolivia. To the west the brownish elaenia's range continues as the Amazon River becomes the Marañón River and proceeds to the headwaters in northern Peru; this is also along the
Xingu-Tocantins-Araguaia moist forests 8 species of primates including the white-nosed saki ("Chiropotes albinasus"), red-handed tamarin ("Saguinus midas"), red-bellied titi ("Callicebus moloch"), Azara's night monkey ("Aotus azarae infulatus") and white-cheeked spider monkey ("Ateles marginatus"). The last two are endemic to this ecoregion and the Tapajós-Xingu moist forests to the west. Other species of mammals include white-lipped peccary ("Tayassu pecari"), collared peccary ("Pecari tajacu"), cougar ("Puma concolor"), jaguar ("Panthera onca"), South American tapir ("Tapirus terrestris"), brocket deer (genus "Mazama"), bare-tailed woolly opossum ("Caluromys philander"), and seven-banded armadillo ("Dasypus septemcinctus"). Endangered mammals include white-cheeked spider monkey ("Ateles marginatus"), black bearded saki ("Chiropotes satanas") and giant otter