Giant Otter – Pteronura brasiliensis

Name

• Common name: Giant otter, giant Brazilian otter, giant river otter.
• Scientific name: Pteronura brasiliensis

Population

• The IUCN Otter Specialist Group estimates a total wild population of 1,000 to 5,000 individuals and an estimated decrease in population of 50% over the next 20 years.

Taxonomy

The giant otter is considered an Endangered species by the IUCN.

• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Order: Carnivora
• Family: Musteliadae
• Subfamily: Lutrinae
• Genus: Pteronura
• Species: Pteronura brasiliensis

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Physical Features

• The giant otter is the largest and the second heaviest (the sea otter is the heaviest) of the Mustelidae or weasel family.
• They reach adult size at 9 to 10 months old.
• Males are from 4.9 to 5.6 ft (1.5 to 1.7 m) and females from 3.3 to 4.9 ft (1 to 1.5 m).
• Males weigh from 57 to 71 lb (26 to 32 kg) and females from 49 to 57 lb (22 to 26 kg)
• It has webbed feet as an adaptation for living in water. It also has a powerful tail which they use to propel themselves in water.
• Its fur is very dense but short, the shortest fur of all otter species. It is usually chocolate brown or red brown.
• Guard hairs are approximately 0.3 inches (8 mm) long and keep water away from the skin.
• Each giant otter has cream fur markings in the chin and throat which are unique in each individual.
• They have sensitive whiskers which allow them to detect prey.

Distribution

• Giant otters live in South America in areas along the Amazon, Orinoco and La Plata Rivers and their tributaries.
• Their distribution covers the rainforest and wetlands of Suriname, the Guianas, Venezuela, Colombia, Ecuador, Peru, Bolivia, Paraguay and Brazil.
• It is extinct in Uruguay and possibly extinct in Argentina.

Habitat

• As a semi-aquatic animal giant otters require land and water to survive.
• Its habitat consists of fresh water rivers, streams, lakes, creeks and springs.
• Its habitat requirements are undisturbed land, banks for denning, overhanging vegetation and high fish density.

Giant Otter Distribution Map.

Behavior

• The giant otter is a social animal contrary to other members of the Mustelidae family.
• They live in cohesive family groups of 5 to 8 members led by dominant monogamous breeding pair and their young from three different breeding seasons.
• When they reach reproductive maturity at 2 to 3 years old they leave their family and form one of their own in a new home territory.
• They establish a home range of about 7.5 sq miles (12 sq km) at the bank of rivers or lakes by flattening vegetation and assembling burrows under fallen logs. They also build a communal latrine.
• They mark their territory with scent from their anal glands. If another animal invade their territory giant otters will defend it.
• This species is diurnal, active during daytime.
• It is the loudest of all species of otters with distinctive vocalizations as communication.
• They spend their day grooming, hunting, communicating and resting.

Reproduction

• Reproductive maturity is reached at around 2 to 3 years old.
• Each family group breeds once a year unless the young did not survive.
• Gestation period is from 64 to 77 days.
• Females give birth in an underground den.
• Litter size is from 1 to 6 with an average of 2. The size of the litter is correlated to habitat quality and group size.
• The young depend on their mother’s milk for at least 4 months.

Diet

• Giant otters are piscivores, consume mainly seasonal fish, up to 8.8 lb (4 kg) a day.
• When fish supply is low they consume turtles, crustaceans, small snakes, small caimans and other river animals.

Life Expectancy

• Giant otters can live up to 10 years in the wild and up to 19 in captivity.

Threats

• In the 1970s the giant otter was nearly brought to extinction due to hunting for its highly prized fur. Hunting for its pelt continues to this day but in a less significant scale.
• Today habitat degradation and loss is the greatest threat they face.
• Mining and logging activities have reduced and polluted their habitat and decreased fish stocks.
• The construction of hydroelectric dams alters river flows resulting in impact in habitat and fish stocks.
• Conversion of forest into agricultural land and human settlement.
• Fishermen kill otters because they are seen as competitors for fish stock.

Conservation Status

• The IUCN Red List of Threatened Species considers the giant otter as an Endangered species.
• The giant otter is listed in Appendix I of the Convention on International Trade in Endangered Species (CITES).

References and Further research

IUCN Otter Specialist Group

IUCN Red List of Threatened Species – Pteronura brasiliensis

World Association of Zoos and Aquariums (WASA) – Giant Otter (pteronura brasiliensis)

ITIS Report – Pteronura brasiliensis

University of Michigan Museum of Zoology – Pteronura brasiliensis Giant otter

The Vocal Repertoire of Adult and Neonate Giant Otters (Pteronura brasiliensis)

U.S. National Library of Medicine National Institutes of Health – Conservation Genetics of the Giant Otter.

BBC Nature – Giant River Otter