Species Fact Profile: Giant Otter (Pteronura brasiliensis)

Giant Otter

Pteronura brasiliensis (Gmelin, 1788)

Range: Northern and Central South America (Amazon, Orinoco, and La Plata River Systems)
Habitat: Slow-Moving Freshwater Rivers, Lakes, Canals, Wetlands
Diet: Fish (especially catfish and perch), Crustaceans, Small Reptiles
Social Grouping: Family groups of 5-8 (up to 20 reported), consisting of a monogamous pair and their offspring.  Territories of about 12 square kilometers
Reproduction: May breed year-round, but primarily spring and early summer.  1-5 pups are born after 65-70 day gestation period; if the litter does not survive, females may have a second litter later in the year.  Cubs are born blind and helpless; eyes open at one month, at which point they begin to follow their parents out of their den.  Mature at 2 years old
Lifespan: 8-10 Years (Wild), 15-17 Years (Zoo)
Conservation Status: IUCN Endangered, CITES Appendix I, USFWS Endangered

• Longest of the world's otter species (the sea otter is more compact and heavier), measuring 1.5-1.8 meters long and weighing 22-32 kilograms; females are slightly smaller.  There are historical records of animals over 2.4 meters long, which may be an exaggeration or may be an indication that the species grew larger before hunting from humans favored smaller animals
• Males and females look alike, with fur various shades of brown (from fawn to reddish to dark), often with an irregularly-shaped cream or white patch on the throat and chest and some white speckling on the face.  When meeting, otters rear up, displaying their throats, possibly using these markings to help recognize one another
• Well-adapted to aquatic life - the feet are heavily webbed, the tail is flattened with a thick, muscular base for paddling, and the nostrils and ears may be closed to keep out water when diving
• Highly social and very vocal, with over twenty reported vocalizations, including a bark for danger, a growl for aggression, a squeak for attention, and a coo for reassuring.  Vocalizations differ from group to group.  Groups may violently defend their territory from outsiders
• Primarily fish alone, but will sometimes work together to capture large prey
• No significant natural predators, but may be taken by jaguar, puma, or large caiman or anaconda (with the otters themselves preying on smaller caiman or anaconda)
• Latin name translates to "Wing Tail of Brazil," referencing their broad, flat tails
• Historically, these otters were heavily hunted for their fur, which is waterproof and luxurious.  They are active by day and very conspicuous, which made them easy to hunt.  Hunting was banned in the 1970s
• Today the major threat is loss and degradation of habitat, as well as depletion of food sources through overfishing.  Sometimes killed by fishermen who view them as a nuisance or competition for fish; otters may also be accidentally caught in fishing nets and drown.  Pups are sometimes illegally taken to be sold as pets.  Also susceptible to diseases, such as canine parvovirus.
• Appear in many native myths and folktales, often in the role of "water people" or allies to humans.  Some myths suggest that humans and giant otters used to fish cooperatively, as still occurs in other parts of the world

Zookeeper's Journal: As a zoo-buff growing up, I viewed the giant otter with the same fascination as giant pandas, Komodo dragons, Sumatran rhinos, and koalas.  At the time, all were near-mythic animals that could only be seen in a single US zoo.  Philadelphia Zoo was the facility that laid claim to America's only giant otters and it was there that I first saw them.  Philly had the distinction of having bred the species, which was no small task - early books that I'd read on otters dismissed the possibility of the species ever being bred - it was hard enough to keep them alive and healthy.  Today, things have changed dramatically.  I won't call these guys plentiful, but I've seen them in half-a-dozen US zoos since my first encounter with them in Philadelphia as a kid, and while I've never worked with them as a keeper, I have gone behind-the-scenes with them and hand-fed them.  For any keeper who's spent time working North American river otters, the giants are incredible up close, so deserving of their Spanish name, Lobo de Rio - River Wolf.  I wouldn't like to share space with them directly - I've heard at least report of a keeper from a South American facility being killed by one.  Looking one of these man-sized weasels in the eye, I can imagine it.