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
Red River of the South receives little precipitation. As a result, much of the river above the Texas–Oklahoma border is intermittent, and until the river is past its great bend south in Arkansas, the flow varies widely. Most of the agriculture in the basin is sustained by groundwater, which is recharged with rainfall and riverflow. The lower course of the river flows through a series of marshes and swamps, where its flow is dramatically moderated. Native American cultures along the river were diverse, developing specialized adaptations to the many different environments. By the time of European contact, the eastern Piney Woods were dominated by the