Giant Otter Pteronura brasiliensis
Giant Otter Pteronura brasiliensis
Red List Status: Endangered
Locations: Amazon, Orinoco, and La Plata river systems across Brazil, Peru, Colombia, Venezuela, Ecuador, Bolivia, Guyana, Suriname, French Guiana, and Paraguay. Populations persist in protected wetlands, slow-moving rivers, and oxbow lakes within the Amazon basin and scattered tributaries throughout northern and central South America.
The agile and graceful tumbling Olympians of the Amazonian rivers, Giant #Otters are able to swim 100 metres in less than 30 seconds. They are also known as the Lobo de Rio (the River wolf), Los Lobos del Rio (Wolves of the River) and Ariranha. They are most active in the mornings and evenings and take a siesta during the hottest parts of the day. Known for their striking size and the chorus of whistles and barks echoing through flooded forests, giant otters are social, vocal, and deeply bonded to their family groups. But the rivers they call home are under siege. The most significant threats to giant otters are anthropogenic pressures of deforestation for palm oil, soy and meat, pollution from mining and climate change. They are also illegally hunted and traded for their pelts or killed in retribution by fishermen. Help them and be #vegan, use your wallet as a weapon and #BoycottPalmOil #Boycott4Wildlife.
https://youtu.be/EAqLxMZ24wY?si=X0tfWCluIuR3ax92
#GiantOtters 🦦💜 are the agile, graceful guardians of Amazonian rivers in #SouthAmerica 🇧🇷 #Endangered by #gold #mining 🚜🔥 #palmoil and cattle ranches. Help them in the supermarket, go #vegan and #Boycottpalmoil #Boycott4Wildlife @palmoildetect https://palmoildetectives.com/2022/09/04/giant-otter-pteronura-brasiliensis/
Share to BlueSky Share to Twitter Giant #Otters 🦦🤎are intelligent and resourceful guardians of the #Amazon #SouthAmerica. 🇵🇪🇪🇨🇧🇷They are #Endangered from #gold #mining, #palmoil #soy and cattle ranching. Help them by going #vegan and #Boycottpalmoil #Boycott4Wildlife @palmoildetect https://palmoildetectives.com/2022/09/04/giant-otter-pteronura-brasiliensis/
Share to BlueSky Share to Twitter Threats
Threats are predominantly related to the river otter being pushed out of their ecosystems by anthropogenic pressures.
The destruction of the river otters’ riparian habitat, overfishing, contamination of aquatic ecosystems (especially for gold mining, fossil fuel exploration, and the use of pesticides and fertilizers for monocultures), domestic animal diseases, and mismanaged tourism It seems likely that mining activities and the widespread conversion of forest into agricultural and pasture lands will continue unabated in the near future as part of the economic development of the Amazonian countries.
Giant otters are threatened by a range of human created hazards including: the illegal pet trade, competition with fishermen, gold and fossil fuel mining and ecosystem conversion to monocultures such as palm oil and soy.
Appearance and Behaviour
Giant otters are the largest members of the mustelid family, reaching up to 1.8 metres in length and weighing between 22 and 34 kilograms. Their sleek, chocolate-brown fur glistens when wet, and each otter sports a unique white throat patch, as individual as a fingerprint. With webbed feet and a powerful, flattened tail, the giant otter is built for speed and grace beneath the surface. They move through water with fluid, serpentine motions, surfacing to snort and chatter with their group.
Giant otters are intensely social, living in family groups of up to 10, communicating with a rich vocabulary of whistles, screams, and barks. A family has a home range of 12 sq. km. They communicate through a noisy series of hums, coos, barks and whistles. They are cooperative and peaceful together and often groom, rest and hunt together and cooperatively construct burrows and establish territories using scent markings from their anal glands to delineate territories.
Newborn pups squeak to elicit attention, while older young whine as they participate in group activities. When intruders invade their territory, the parents and other adults in communities will defend the offspring against danger. Their playful nature is evident as they slide down muddy banks or toss fish to one another, but every action is purposeful—defending territory, nurturing young, or foraging together as a tight-knit team.
Threats
Palm oil and agricultural deforestation
The Red List classifies the giant otter as Endangered, with palm oil expansion and agricultural deforestation posing severe threats. Forests are stripped bare along riverbanks for plantations and grazing, leaving otters exposed and vulnerable. As vegetation disappears, riverbanks erode, dens collapse, and the intricate web of life that sustains the giant otter unravels. The destruction is relentless, turning vibrant wetlands into silent, empty channels.
Gold mining and water pollution
Gold mining scars the Amazon, releasing mercury and other toxins into waterways. These poisons accumulate in fish—the giant otter’s primary food source—and in the otters themselves, causing illness and reproductive failure. Mining dredges churn up riverbeds, clouding the water and destroying the submerged vegetation that shelters otter families. Pollution from agriculture and mining is now one of the leading causes of population decline, with entire river systems rendered uninhabitable for years at a time.
Overfishing and prey depletion
Overfishing by humans strips rivers of the catfish, characins, and perch that giant otters depend on. As fish stocks dwindle, otter families are forced to expand their territories or go hungry. Competition with commercial fisheries intensifies during the dry season when water levels drop and prey becomes scarce. The loss of food drives otters into conflict with humans and increases the risk of starvation, especially for pups.
Hunting and direct persecution
Historically, giant otters were hunted for their luxurious pelts, leading to catastrophic population crashes. Although hunting is now illegal in most range countries, illegal killing persists, driven by fear, competition, or ignorance. Otters are sometimes shot by fishers who see them as rivals, or trapped in snares set for other animals. Each loss tears at the fabric of otter society, as these animals rely on strong family bonds for survival.
Habitat fragmentation and climate change
The patchwork of remaining habitat isolates otter populations, reducing genetic diversity and making recovery difficult. Climate change brings unpredictable floods and droughts, altering the rhythm of the rivers and the abundance of fish. As the Amazon warms and dries, the future of the giant otter hangs in the balance, tied to the fate of the forests and waters they call home.
Diet
Giant otters are expert fish hunters, preying primarily on catfish, perch, and characins. Their hunting is a spectacle—sleek bodies slicing through water, eyes alert for the flicker of scales. Otters hunt cooperatively, corralling schools of fish and snatching them with lightning speed. During periods of low fish abundance, they may supplement their diet with crustaceans, small reptiles, or amphibians. Seasonal floods and droughts shape their foraging patterns, with families moving between oxbow lakes and river channels to follow the shifting bounty of the Amazon. Every meal is a communal event, with otters sharing catches and calling family members to feast.
Reproduction and Mating
Giant otter breeding peaks in late spring and early summer, though some pairs mate year-round. Females are receptive for three to ten days of a 21-day oestrous cycle, with courtship and mating taking place in the water. After a gestation of 65 to 70 days, the female gives birth to two to five altricial pups in a den dug into the riverbank. Pups are born blind and helpless, relying entirely on the care of both parents and older siblings. The family’s social bonds are strongest during this period, with constant grooming, feeding, and play. Pups emerge from the den at around four weeks, learning to swim and hunt under the watchful eyes of the group. In the wild, giant otters can live up to 15 years, although most do not reach this age due to the many dangers they face.
Geographic Range
These energetic mustelids are endemic to South America, with populations distributed east of the Andes in the Orinoco, Amazonas, and Parana basins, and the hydrographic networks of the Guianas.
Giant otters inhabit the slow-moving rivers, oxbow lakes, and wetlands of the Amazon, Orinoco, and La Plata basins. Their range spans Brazil, Peru, Colombia, Venezuela, Ecuador, Bolivia, Guyana, Suriname, French Guiana, and Paraguay. Once widespread, giant otters have vanished from Uruguay and Argentina, and their populations are now fragmented, surviving mainly in protected reserves and remote tributaries. In Bolivia, only about 350 individuals remain, mostly within national parks. The sounds of the giant otter—chirps, whistles, and splashes—are now rare in many rivers where they once flourished.
FAQs
What is the current population size of the giant otter Pteronura brasiliensis?
Wild populations of the giant otter are estimated at between 4,400 and 7,600 individuals, with numbers declining due to ongoing habitat loss, pollution, and hunting. In some regions, such as Bolivia, only a few hundred remain, mostly in protected areas. The largest populations are found in the Amazon and Orinoco basins, but even here, otters are increasingly isolated by deforestation and river degradation (Groenendijk et al. 2015).
How long do giant otters live in the wild?
In the wild, giant otters can live up to 15 years, although the average lifespan is closer to 4.5 to 5.5 years due to predation, disease, and human threats. In captivity, some individuals have reached 17 to 20 years, but such longevity is rare in the wild (Groenendijk et al. 2014).
What are the main threats for the giant otter?
The greatest challenges facing the giant otter are palm oil-driven deforestation, gold mining, water pollution, overfishing, and habitat fragmentation. These threats destroy riverbank vegetation, poison waterways, and deplete fish stocks, undermining the otters’ ability to survive and reproduce. Effective protection requires indigenous-led conservation, agroecology, and the safeguarding of river ecosystems from further industrial encroachment (Mongabay, 2025).
Do giant otters make good pets?
Giant otters do not make good pets. Captivity causes extreme stress, loneliness, and early death for these highly social, intelligent animals. The illegal pet trade tears families apart and fuels extinction, as pups are stolen from their dens and forced into unnatural, impoverished conditions. Protecting giant otters means rejecting the illegal pet trade and supporting their right to live wild and free in their forest and river homes.
Take Action!
Fight for the survival of the giant otter every time you shop—#BoycottPalmOil #Boycott4Wildlife. Support indigenous-led conservation and agroecology. Reject products linked to deforestation, gold mining, and the illegal wildlife trade. Adopt a #vegan lifestyle and #BoycottMeat to protect wild and farmed animals alike. Every choice matters—stand with the giant otter and defend the rivers of the Amazon.
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Further Information
Groenendijk, J., Marmontel, M., Van Damme, P., Schenck, C., Schenck, C. & Wallace, R. 2021. Pteronura brasiliensis. The IUCN Red List of Threatened Species 2021: e.T18711A164580466. https://dx.doi.org/10.2305/IUCN.UK.2021-3.RLTS.T18711A164580466.en. Accessed on 27 August 2022.
Groenendijk, J., Hajek, F., Duplaix, N., Reuther, C., Van Damme, P., Schenck, C., … & Waldemarin, H. F. (2015). Pteronura brasiliensis (Carnivora: Mustelidae). Mammalian Species, 49(953), 97–108. https://doi.org/10.1093/mspecies/sev011
Mongabay. (2025). Researchers identify 22 key areas for protecting struggling giant otters. https://news.mongabay.com/2025/06/researchers-identify-22-key-areas-for-protecting-struggling-giant-otters/
Giant Otter Pteronura brasiliensis
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