The
Giant Otter (
Pteronura brasiliensis) is a
South American carnivorous mammal. It is the longest member of the
Mustelidae, or
weasel family, a globally successful group of predators. Unusually for a mustelid, the Giant Otter is a social species, with family groups typically supporting three to eight members. The groups are centered on a dominant breeding pair and are extremely cohesive and cooperative. Although generally peaceful, the species is territorial and aggression has been observed between groups. The Giant Otter is
diurnal, being active exclusively during daylight hours. It is the noisiest
otter species and distinct vocalizations have been documented that indicate alarm, aggressiveness, and reassurance. The Giant Otter ranges across north-central South America.
Its distribution has been greatly reduced and is now discontinuous. Decades of poaching for its velvety pelt, peaking in the 1950s and 1960s, hugely diminished population numbers. The species was listed as endangered in 1999 and population estimates are typically below 5,000 in the wild. The Guianas are the last real stronghold for the species. It is the most endangered mammal in the neo-tropics. Habitat degradation and loss is the greatest current threat. The Giant Otter is also rare in captivity as of 2003, only 60 animals were held.[3]
The Giant Otter shows a variety of adaptations suitable to an amphibious lifestyle, including exceptionally dense fur, a wing-like tail, and webbed feet. The species prefers freshwater rivers and streams, which are usually seasonally flooded, and may also take to freshwater lakes and springs. It constructs extensive campsites close to feeding areas, clearing large amounts of vegetation. The Giant Otter largely subsists on a diet of fish, particularly characins and catfish, and may also eat crabs. It has no serious natural predators other than humans, although it must compete with other species, including the Neotropical Otter and caiman species, for food resources.
The Giant Otter has a handful of other names in English. River Wolf (Spanish Lobo del Río) and Water Dog (Spanish Perro del Agua) are used occasionally. The last of these may have been more common in the reports of explorers in the nineteenth and early twentieth centuries.[4] All three names are in use in Spanish and Portuguese, with a number of regional variations. "Giant Otter" translates as Nutria Gigante and Lontra Gigante in Spanish and Portuguese, respectively; a fourth name, Ariraí or Ariranha is also in use in South America.[5] Among the Achuar people, they are known as Wankanim,[6] and among the Sanumá as Hadami.[7][8] The genus name, Pteronura, is derived from the Ancient Greek words pteron/πτερον 'feather' or 'wing' and ura/ουρά 'tail',[9] a reference to its distinctive wing-like tail.[10]
