Some animal species interest the general public, and not just the reduced circle of keen nature lovers. There are a large number of such charismatic animals; any list of them would include marine mammals, bears, wolves, sea turtles, and large African wildlife. These species are endearing, frightening and impressive, bound up with our fears and fantasies, and for centuries they have been part of our collective unconscious, as well as being evidence of the extraordinary diversity that nature can produce. Whilst probably less well known to the general public than African wildlife, Amazonian wildlife has its fair share of species with significant names, such as the jaguar, macaw, spider monkey, tapir, anaconda, black caiman,  or even the giant otter.

It must then be admitted that observation conditions in the Amazonian forest are not the same as those on the African savannahs. The dense shady undergrowth, low natural density of the animals, and their disconcerting shyness all diminish the already slim chances of observing them. Unlike most large species with cryptic* behavioural patterns, the giant otter (Pteronura brasiliensis) is a curious, noisy, social, playful, diurnal animal that normally lives in open habitats. It is thus one of the most frequently observed large Amazonian mammals, meaning that it is a favourite amongst tour operators ranging from the Pantanal in Brazil to Peruvian Amazonian.

The animal has acquired its own fair share of superlatives, being the largest and oldest of the thirteen species of otter found around the world. It appeared over 6 million years ago and is now the largest member of the Mustelidae family, measuring one metre eighty and weighing 30kg. The giant otter is also in the top four large predators in South America after the black caiman, the jaguar, and the puma. It is therefore no surprise that it attracts nature lovers.

Over the past fifteen years or so, several initiatives have been set up as part of ecotourism projects to promote the presence of the giant otters. This has mainly been the case in Brazil and Peru, where the species is a leading “attraction” for some tour operators who have worked with local communities and the authorities in charge of managing protected areas. Although found and regularly observed at most rivers in French Guiana, there is no site here for the supervised observation and monitoring of giant otters as yet.

The Queen of the rivers

Apart from its size, the giant otter may be distinguished from other South American otters by the cream-coloured markings on its throat and neck. Its physical form reminds us that it is perfectly adapted to its aquatic habitat. With its long undulating body, short paws, webbed toes, and long flat tail, it has everything it needs for life in the water. The large number of sensory vibrissae* around its eyes and whiskers also supplement its vision when diving. All in all, the otter is as at ease as a fish in water. This is unfortunate for the fish, however, for the otter is designed for underwater hunting and can consume more than 3kg of fish each day. It appears to prefer fish from the erythrinidae family (including the wolf fish) and the serrasalus family (including the piranha).

Giant otters are particularly fond of shallow, slow-flowing rivers. This is where they find large numbers of prey which are easier to catch than in the middle of a major river. The small forest creeks in the Guiana Shield region are the ideal habitat for this species. Other sorts of habitat can also meet their needs, however, such as the flooded savannahs of the Pantanal in Brazil and the Kaw region of French Guiana. Some shallow lakes are also home to giant otters.


These wetland habitats are where the animal establishes its territory, which can extend over more than 100km2 and along branches of river up to twenty kilometres in length. In order to avoid confrontation with their fellow creatures, giant otters actively mark their territory with urine, faeces, and areas they scratch or clear, acting as olfactory and visual signals to mark their presence. Giant otters also establish “camps” at strategic spots, which they use as a surveillance point, to rest and groom. These carefully cleared zones are heavily marked and otters visit them regularly. At the heart of their home range are the burrows where the females give birth during the dry season. The baby otters stay there for up to six weeks before venturing outside with their parents.

Family is important for giant otters. They live in family groups based around the founding couple. The baby otters born that year live with their parents, of course, but also brothers and sisters of the two previous years. The groups generally consist of between 3 and 8 individuals. If everybody is in good health and no major crises perturb their peaceful existence, however, then the family can include 10 or even 12 otters. Giant otters have developed a fairly complex vocal repertoire to communicate and stay in contact with each other. People who have come across a group can vouch for how noisy this creature is. This family life has a large number of advantages, both in terms of improving efficiency when hunting for food and protecting the young and territory from any predators and intruders. Who could these be, however? Giant otters have very few predators. Baby otters or lost, young adults are mainly the ones who could get eaten by an anaconda, caiman, or jaguar. When confronted with the entire family, however, the chances of these predators taking an otter are slim and the situation can even backfire on them! As for intruders, this might be another group of otters straying over the territorial boundaries or a caiman after the same fish.

Contrary to what might be expected, the presence of the neotropical otter (Lontra longicaudis) in the same zones does not seem to pose any problems for cohabitation. In ecological terms, the neotropical otter is flexible enough not to interfere with the daily life of the giant otters. It consumes markedly smaller prey and is quite content with a burrow that has been abandoned by its larger relatives.

On reading this you may think that everything is for the best in the world of giant otters, yet the species is on the “endangered” category of the International Union for the Conservation of Nature (IUCN) Red List, meaning that its numbers are expected to halve by 2030.

Exterminated for its fur, threatened by gold mining

Giant otters were hunted for their fur during the 1950s and 1960s, and had been pushed to the verge of extinction by the beginning of the 1970s. They were easy targets and tens of thousands of creatures were killed by hunters trading in their skins until the Washington Convention (CITES) forbade it in 1973, when most countries where the species could still be found began to protect it. According to the IUCN, the giant otter has already disappeared in Argentina and Uruguay and is becoming much rarer in many zones where it can still be found. The largest remaining populations are in the Guiana Shield region and in the vast wetlands of Pantanal in Brazil.

Nowadays, the species must face new threats – the destruction and pollution of its habitats. The gold fever affecting many regions in South America, fuelled by the price of gold which has hit vertiginous levels, has had severe consequences on aquatic habitats. The factors laying waste to the rivers and their occupants include the diversion of rivers, the massive quantities of mud which are discharged, and hydrocarbons and mercury polluting the water. The giant otters, which are at the top of the food chain, are slowly but surely being poisoned by the large quantities of methylmercury, as is also the case for people who use the rivers. This is the form in which mercury becomes concentrated as you move up the food chain. Unfortunately, mercury is still being used extensively on a large number of illegal workings, despite being banned in French Guiana in 2006. Another consequence of looking for gold is that the tons of mud which are suspended in the water are asphyxiating aquatic life and gradually killing off the fish which the otters eat. Lastly, major structural modifications to watercourses can disturb the territorial organisation of the species and weaken groups.

An indicator of the quality of aquatic habitats?

The giant otter has been studied since the 1970s, and there has been much research on its behaviour, social relations, diet, and the ways it uses its territory. These studies were mainly carried out in Surinam, Brazil, and Peru, and were unheard of in French Guiana for a long time.

Since 2000, the Kwata Association has been developing supplementary projects in French Guiana relating to the conservation of the species and its habitats. These use the giant otter as an indicator of the quality of aquatic habitats as a whole. In 2008, this became part of the SPECIES programme carried out in partnership with WWF France, which also focuses on studying the jaguar and tapir. By studying these three species, it is possible to develop conservation instruments as they are all sensitive to the threats to them and their role within the ecosystems.

In the case of otters, it is a question of understanding how the populations react to disturbances to their habitats, identifying the most favourable zones for maintaining healthy populations, and understanding the relations which might exist between groups from different geographical zones. By combining field searches for clues of their presence, molecular biology in the laboratory, and the modelling of habitats using a geographical information system (GIS), the results tell us a bit more about the status of the giant otter in French Guiana. Initial results confirm the hypothesis of the IUCN: unlike other regions in South America, the giant otter is still present in all of the river basins in French Guiana. It would also seem that the species is found in larger numbers on the higher parts of rivers. This confirms the idea that in order to maintain aquatic biodiversity, it is necessary to preserve the heads of creeks.

Nevertheless, the current study also shows that the species is becoming rarer on certain rivers due to human activity. This is shown by fewer indications of their presence being observed in the field, as well as observations of small groups. This reveals breeding failures and the difficulties giant otters have in ensuring the survival of their young on territories which have been disturbed.

Once again, in comparison to the harm being done to giant otter populations in other countries, French Guiana is not doing too badly. But how long will this last? Illegal gold mining has taken on dramatic proportions over the past few years and is affecting the hearts of protected areas. The difficulties encountered by the State in getting to grips with the phenomenon do not bode well for those species which rely on good quality aquatic habitats.