Amazon river dolphin widespread river dolphins. They are present in six countries in South America: Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela, in an area covering about . The boundaries are set by waterfalls, such as the Xingu and Tapajós rivers in Brazil, as well as very shallow water. A series of rapids and waterfalls in the Madeira River have isolated one population, recognized as the subspecies "I. g. boliviensis", in the southern part of the Amazon basin in Bolivia. They are also distributed in the basin of the Orinoco River, except the Caroni River and the upper Caura River in Venezuela. The
River tyrannulet mostly contiguous stretches, about 100 to 150 km in width. The rivers in the Amazon Basin, going upstream are the following: Amazon River, (Tocantins, Araguaia— east of the Xingu), Xingu River, Madeira, and Marañón-Ucayali, (in Amazonian Peru). For the Araguaia River, the bird's range continues only downstream to the Tocantin confluence, then down the Tocantins to the Pacific, (500 km east of the Amazon River outlet; the Xingu River confluence range connects to the Tocantins range.) On the Madeira River, from Amazonian Bolivia, the range only extends into the country by 300 km of the 2300 km Madeira River range.