In Search of the Endangered ‘River Wolf’

River Wolf or Lobo de río is the very evocative Spanish name for one of the South America’s rarest and most dazzling mammals, the Giant River Otter (Pteroneura brasiliensis).

Seeing and photographing the elusive otter has been on my priority list for a long time.  In June 2007 I made my first attempt, but bad weather prevented my final flight into the Amazonian Ecuador.  Two years later in 2009 I visited the floorplain of Manu National Park in south-eastern Peru, home to around 20 families or 100 individuals of these large otters, but after a full week’s stay in this otherwise exciting National Park, I had still no images of the Giant River Otter.

Giant_Otter_areaThe Giant River Otter range is across North-central South America; it lives mainly in and along the Amazon River Delta and in the Pantanal. Its distribution has been greatly reduced and is now discontinuous.


Some five year later after more research I had an opportunity to spend two weeks in the Pantanal, which is the world’s largest wetland area located mostly within the Brazilian state of Mato Grosso do Sul.

The Pantanal is Brazil’s wildlife wonderland.  However, like most other places on our plant, Latin America is no longer a safe continent for large mammals and many are Endangered like the Giant Otter.  However, this time I was not to be disappointed.


Already on the 2nd day did we come across this Alpha male ‘periscoping’ out of the water to keep an eye on the newly arrived visitors.  Interesting to observe that at no time did I observe any indication of stress, probably a good sign that there is little or no hunting pressure in most parts of the Pantanal.  Each individual has different throat markings.  It grows up to a impressive length of 1.7 m (5 feet 7 in) weighing in at over 30 kg (66 lbs).


On the third morning my guide told me that this was the first time that this 2 months’ old cub was outside the den; still not able to swim properly, the mother was carrying the cub around, with other family members close by.


Cubs are reared in a central den area, which connects to an adjacent waterway often via a series of tunnels.  Adults will maul fish and present them half-dead to cubs.


After around 3 months, cubs are able to swim and fish by themselves, but they may remain with their group for up to 4 years, helping care for the newest young.


Fish make up most of the giant river otter’s diet. They hunt alone or in groups, many times using coordinated efforts, and must be successful often to meet their high daily intake requirement.


Each adult eat up to four kg (nine lb) of food per day.  Above is a Suckermouth Catfish (Hypostomus plecostomus) being eaten.  Fish (including piranha) are supplemented by crustaceans, and other river creatures like turtles and snakes.   The otter can attack from both above and below. When they catch their own food it is consumed immediately; they grasp the fish firmly between the forepaws and begin eating noisily.



The Giant River Otter has a nice set of teeth ideal for catching and holding fish.



The Giant River Otter has no serious natural predators other than humans, although it must compete with other species, including the Neotropical Otter for food resources.  The Yacare caiman (Caiman yacare) see here, shares the same habitat, but is not agile enough to be a serious threat to the Giant River Otters.


Family groups are composed of a dominant breeding pair and the offspring from several breeding seasons.  Within groups, the animals are extremely peaceful and cooperative. Group hierarchies are not rigid and the individuals easily share different roles.


Giant river otters have been hunted extensively, and sadly they are now among the rarest otters in the world—only a few thousand are believed to survive in the wild. Giant Otters are highly susceptible to persecution: they are large, easily visible, very social, and vocal. They are diurnal and occupy open habitats and stable territories.  They good news is that they are recovering well in the Pantanal!




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