Giant Otter, the "Water Dog"

Of the more than a dozen otter species in the world (all members of the Subfamily Lutrinae), the Giant Otter is the largest and rarest.  It only lives in South America, and is only one of two otters recorded in Iwokrama Forest. The other much more common species, the Neotropical River Otter (Lontra longicaudis) lives in both Central and South America.  Otters share the Family Mustelidae with skunks, weasels, badgers, among others.

Their curious nature, ravenous appetite, affinity for humans, and size are probably the reasons why these aquatic creatures are known as "water dogs".

Giant Otter

Pteronura brasiliensis

Physical Description

Adults may be as long as 2 metres (6 ft.) and weigh up to 30 kilos (70 lbs.). Like that of their Mustelidae cousin the mink, Giant Otter fur is extremely soft.  It is uniformly chocolate brown with the exception of large creamy white patches on the underside of the otter's long necks. Each individual's patch is unique and therefore aids tracking specific otters for research purposes. With large webbed feet and a stout flat tail, they are well adapted to their watery environment. Claws help them catch and eat their prey.

Habitat

Giant Otters live in generally very remote, often forested regions, usually far from human habitation.  They prefer bodies of water with gentle currents, such as rivers, lakes, and flooded areas.

Like other otter species, Giant Otters are adept at

"aquatic dining" and are often spotted doing so.

(Photo © A. Holland / G. Duncan)

Diet

Giant Otters are a top predator of their freshwater environments. Due to their size and swimming speed they compete successfully for fish with Jaguars and Black Caimans. They hunt alone or in groups, and close their ears and nose when diving. An adult otter may consume up to 4.5 kilos (10 lbs.) of fish per day, making them extremely susceptible to any changes in fish populations. Giant Otters supplement their fish diet with crustaceans and small snakes or caimans. Prey are often held on the chest and eaten in the water, or but may be dragged to a bank.

Family Life

Giant Otters are very social animals and live in family groups of 5 to 10 members consisting of a pair of adults and one to five cubs of varying ages. Offspring remain with their parents for several years. The group sleeps at night in a burrow on the riverbank, the burrow entrance is above water. Their average life span in the wild is 12 years.

A Giant Otter group surveys their photographer.

Status in the Wild

Once found throughout lowland tropical rainforests of northern South America, Giant Otter populations decreased dramatically by the 1970's due largely by demand for their pelts. Their population in Guyana also suffered greatly, likely due to the close proximity of the Rupununi range to Brazil, allowing for easy smuggling of pelts across the border.

Fortunately, over the past 30 years, populations have been increasing in the Guianas. However, they are still only found in the more remote waterways of the Guianas such as the Rupununi, Essequibo, Abary and Mazaruni Rivers (as well as the Amazon Basin).

Guyana's Giant Otters were first documented at the Karanambo Ranch in the North Rupununi in 1988. A stable population has been present in the area since then and has been chronicled through the Giant Otter rehabilitation work of Diane McTurk at Karanambo Ranch.

Presently the greatest threat to these otters is from loss of habitat and poisoning due to polluted waterways. Gold mining is a danger because otters bio-accumulate mercury in their bodies; mercury is used in the region's gold mining industry. Deforestation and agriculture also lead to increased silting of creeks and rivers, which in turn leads to changes in the population of their primary food source. Giant Otters are very sensitive to other human activities as well. Motor engines and river camps can lead to otters moving to more remote areas.

As of 11th November 2004:

• Listed as Appendix I by the Convention of International Trade of Endangered Species (CITES) - threatened with extinction.
• Listed as Endangered by the International Union for the Conservation of Nature (IUCN) Red List - high risk of extinction in the wild. IUCN has prohibited all trade in Giant Otter pelts.