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
Tapajós-Xingu moist forests Tapajós-Xingu moist forests The Tapajós-Xingu moist forests (NT0168) is an ecoregion in the eastern Amazon basin. It is part of the Amazon biome. The ecoregion extends southwest from the Amazon River between its large Tapajós and Xingu tributaries. The Tapajós-Xingu moist forests lie between the Tapajós river to the west and the Xingu rivers to the east, tributaries of the Amazon River to the north. They have an area of . The rivers act as barriers to the movement of plants, animals and insects to and from adjacent regions. In the south the rugged Serra do Cachimbo divides the ecoregion