The Amazon rainforest is the moist tropical forest that covers about 6 million km² of South America's 7-million-km² Amazon basin, spread across nine countries: 60% of it lies in Brazil, 13% in Peru and 10% in Colombia, with smaller shares in Bolivia, Ecuador, Venezuela, Guyana, Suriname and French Guiana. It is the largest and most biodiverse tract of tropical rainforest on Earth, with an estimated 390 billion trees belonging to about 16,000 species. Roughly one in ten of the world's known species lives there. Scientists have so far classified at least 40,000 plant species, 2,200 fishes, 1,294 birds, 427 mammals, 428 amphibians and 378 reptiles in the region. Its geography is best read through the animals and plants that define its main habitats: the high terra firme forest, the seasonally flooded várzea along the rivers, and the canopy above both. Each section below ties one group of species to a named place and the figures surveys have produced there.
Brazil Nut Trees and Agoutis: Counting 16,000 Tree Species from Yasuní to Manu
Tree surveys show how unevenly the forest's diversity is spread. Some of the richest forest lies in the far west, where the Andes meet the lowlands. In Ecuador, Yasuní National Park covers roughly 10,000 km² between the Napo and Curaray rivers, less than 0.15% of the Amazon basin. It holds at least four world records for documented tree and liana richness, and a 2001 study found more than 1,100 tree species in a single quarter square kilometre of Ecuadorian rainforest. Yasuní became a UNESCO Biosphere Reserve in 1989. In August 2023 Ecuadorians voted in a referendum to halt oil drilling in the park, which sits on an estimated 1.7 billion barrels of crude.
Farther south, in Peru, surveys in Manu National Park have identified 4,385 plant species, including 1,108 tree species in plots between the lowland forest and the mountain tree line, and as many as 250 tree species in one hectare. Among the lowland giants recorded there is the Brazil nut (Bertholletia excelsa). It grows up to 50 m tall with a trunk 1–2 m across, can live for 500 years or more, and holds its crown above the surrounding canopy. Its relationships show how tightly Amazon species depend on one another. Only large-bodied bees, of genera such as Bombus, Centris and Eulaema, can pollinate its flowers, so it fruits almost only in undisturbed forest. The fruit takes 14 months to ripen into a woody capsule weighing up to 2 kg and holding 8 to 24 seeds. Large rodents such as agoutis gnaw it open. They eat some seeds and bury others in caches during the wet season, and a few of those buried seeds grow into new trees. Plantations have been tried, but their production is low and not currently economically viable, so most of the crop comes from the forest itself: 79,736 tonnes (in shell) worldwide in 2024, 87% of it from Brazil and Bolivia.
Pink River Dolphins, Arapaima and White Uakaris in the Flooded Forest of Mamirauá
Along the big whitewater rivers, the forest floods every wet season, and a different set of species takes over. The Mamirauá Sustainable Development Reserve, near Tefé in Amazonas state, Brazil, covers 11,240 km² of várzea between the Solimões (the upper Amazon), the Japurá and the Auati-Paraná channel. Mamirauá is listed as a Ramsar wetland of international importance, and in 2003 it was added, together with the Anavilhanas National Park and the Amanã reserve, to Jaú National Park to form the Central Amazon Conservation Complex World Heritage Site. About 6,300 people live inside the reserve, including caboclo riverside communities and Ticuna, Cambeba and Cocama groups.
Both of the basin's river dolphins can be watched in the reserve, the tucuxi and the larger boto, or Amazon river dolphin (Inia geoffrensis). Male botos can reach 2.5 m and 185 kg, and adults turn pink, more strongly in males. Unfused vertebrae and large flippers let them steer between submerged tree trunks when the forest floods. They take at least 53 species of fish, from catfish to piranhas, as well as river turtles and crabs. In 2018 the IUCN listed the species as endangered, with a declining population, citing fishing lines, hunting for bait, dams and pollution. Our guide to Amazon river dolphins covers both species in detail.
The same waters hold the arapaima, or pirarucu (Arapaima gigas), one of the largest freshwater fish in the world. It commonly reaches 2 m, and adults can weigh 200 kg. Because it must surface to breathe every 5 to 15 minutes, it was easy to harpoon and was heavily overfished. Brazil banned arapaima fishing outright from 1996 to 1999 and then allowed it only in designated areas under managed quotas. Counted stocks in those areas grew from about 2,500 fish in 1999 to more than 170,000 in 2017, though about 77% of the lower Amazon harvest was still estimated to come from illegal fishing. Mamirauá also has two primates found nowhere else: the white uakari, a bald, crimson-faced monkey of the várzea, and the black-headed squirrel monkey. Its bird list passes 400 species, among them toucans and the hoatzin, whose chicks have claws on their wings. Jaguars may even remain in the forest through the months when its floor is under water. The yearly flood cycle that shapes all of this is explained in our article on the Amazon floodplain.
Harpy Eagles and Sloths: The Parintins Nest Study
Above the canopy, in the emergent layer where trees such as the Brazil nut rise clear of the rest, lives the forest's top aerial predator. The harpy eagle (Harpia harpyja) is the largest bird of prey across its range and has the largest talons of any living eagle. It hunts mostly from perches, scanning the trees and then diving on prey, and can carry animals of up to about half its own body weight.
One detailed picture of its diet comes from a nest at Parintins in Amazonas state, Brazil. Between 2003 and 2005, researchers led by Aguiar-Silva collected the remains of prey that the adults brought to their chick. Sloths made up 79% of it: 39% brown-throated sloths and 40% Linnaeus's two-toed sloths. At 10 nests in Amazonian Ecuador, cebid monkeys made up 35% of the remains (species taken include capuchins, howlers and spider monkeys), and camera traps and literature reviews have now recorded 116 prey species in all. By hunting capuchin monkeys, which prey heavily on birds' eggs, harpies help keep those mesopredators in check. The eagle is still recorded in Manu, where more than 1,000 bird species have been estimated, and it is nearly extirpated from much of Central America as forest has been cleared.
Jaguars and Giant Otters in Manu National Park
Manu, created by decree on 29 May 1973 and listed as a World Heritage Site in 1987, protects 17,163 km² of Peru's Madre de Dios and Cusco regions. It runs from Andean grassland near 4,000 m down to lowland rainforest, and about 160 mammal species have been reported there. Two of them sit at the top of their food chains.
The jaguar is an apex predator, and the Amazon is now its only remaining stronghold. By one 2018 estimate the species' range had shrunk by 55% over the previous century. In dense Amazon forest, jaguars are active mostly by day. They also need more space here than in the Pantanal: female home ranges reach about 53.6 km² in the Amazon against 15.3 km² in the Pantanal, and males about 180.3 km². Jaguars hunt by stalking and ambush, and on floodplains they opportunistically take caiman, green anacondas and turtles. Their bite can pierce the shell of the yellow-spotted Amazon river turtle.
The giant otter (Pteronura brasiliensis) is the longest member of the weasel family, at up to 1.8 m. Brazilians call it ariranha or onça-d'água ("water jaguar"), and in Spanish it is the "river wolf". It lives in family groups of three to eight and hunts by day, mainly for cichlids, characins such as piranhas, and catfish. Poaching for its pelt peaked in the 1950s and 1960s. The species was listed as endangered in 1999, and wild numbers are generally estimated at fewer than 5,000. The Guianas remain a stronghold, and the Peruvian Amazon gives it modest numbers and strong protection. Researchers working in Peru in the 1990s proposed no-go zones, viewing towers and a 50 m minimum distance to keep tourists from disturbing family groups.
Counting What Remains: Species Tallies, Fires and the 26% Already Lost
Every count above is a snapshot of a forest that is shrinking. By 2022, around 26% of the Amazon rainforest was considered deforested or highly degraded. Satellite data showed about 7,900 km² cleared between August 2017 and July 2018 alone, with Mato Grosso and Pará hardest hit, and cattle ranching accounts for about 80% of deforestation in the Brazilian Amazon. Fire spreads the damage further. Over 90% of Amazonian plant and vertebrate species, some 13,000–14,000 in total, may have been affected to some degree by fires.
Those tallies are certain to rise. Brazil alone has between 96,660 and 128,843 described invertebrate species, the region may hold around 2.5 million insect species, and a single hectare of Yasuní has been estimated to hold over 100,000 insect species. Losses in the places named here show how the pressures interact. Botos are caught in fishing gear, arapaima recovered only after a ban and local management, harpy eagles disappear wherever the canopy is cut, and giant otters are pushed out where rivers are disturbed. In Bolivia the picture is reversed: arapaima escaped from fish farms in Peru's Madre de Dios region and spread into the Beni basin, where it is now treated as an invasive species. The reserves that hold the forest together, from Manu (1973) to Mamirauá and the Central Amazon Conservation Complex (2003), protect only part of the basin. Where the forest is being cleared fastest, and why, is mapped in our guide to Amazon deforestation.