Giant OtterPteronura brasiliensisWhere and when to see them

The giant otter is a large, highly social freshwater mammal native to South America. It belongs to the weasel family, Mustelidae, and is the longest living otter species. The Amazon basin is a major stronghold, although its range also includes other tropical South American river systems. Historically depleted by hunting for its fur, it now faces habitat loss, water pollution, conflict with fisheries, and disturbance. Protecting connected waterways and undisturbed riverbanks is essential to its survival.

Size

Adults usually measure 1.5–1.8 m in total length, including the tail; large males can approach 2 m.

Weight

Typically 22–32 kg, with males generally heavier than females.

Lifespan

Around 10 years in the wild; up to about 17 years in human care.

Status

Endangered (IUCN).

Giant otters are active mainly during daylight, alternating hunting trips with rest, grooming, and social contact. They live in family groups usually centered on a breeding pair and their offspring. Group members travel together and may hunt alongside one another, although individual otters generally catch their own prey. A varied vocal repertoire helps them maintain contact, signal alarm, and coordinate social interactions. Families defend territories and mark regularly used bankside sites with scent and communal latrines. They use dens excavated in riverbanks for shelter and raising cubs. Older offspring and other group members help protect and care for the young.

• Each giant otter has a distinctive throat pattern that researchers can use for identification.
• Its dense fur traps air to help insulate its body in the water.
• It can close its ears and nostrils when diving.
• Older siblings help care for cubs within the family group.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

Giant otters inhabit freshwater rivers, creeks, lakes, and wetlands in tropical South America. In the Amazon, they are particularly associated with fish-rich tributaries, oxbow lakes, and floodplain waterways. They need suitable banks for dens and resting sites, often with substantial vegetation cover. Seasonal flooding changes access to feeding areas and can draw groups into flooded forest and connected wetlands. Healthy fish populations and limited human disturbance are important features of suitable habitat.

Fish make up the great majority of the giant otter's diet, including cichlids, catfish, and characins such as piranhas. It pursues prey underwater and often holds a captured fish in its forepaws while eating at the surface. Crustaceans and other aquatic animals are taken occasionally. The species and sizes of fish eaten vary with local availability and seasonal water conditions.

Common name

Giant Otter

Scientific name

Pteronura brasiliensis

Animal group

Mammals

Size

Adults usually measure 1.5–1.8 m in total length, including the tail; large males can approach 2 m.

Weight

Typically 22–32 kg, with males generally heavier than females.

Lifespan

Around 10 years in the wild; up to about 17 years in human care.

Status

Endangered (IUCN).

Identification

Look for a long, muscular body, short dark-brown fur, and a conspicuous cream or white throat patch. The broad head has small rounded ears, while large webbed feet and a flattened, powerful tail aid swimming. Each individual's throat markings form a distinctive pattern. Compared with the Neotropical otter, the giant otter is much larger, has a more flattened tail, and is more often seen in conspicuous, vocal family groups.