AnimalTracks.wiki

What the sources say

Giant River OtterPteronura brasiliensis

Every figure, record and mechanism on the Giant River Otter profile was written from a source, and this is the working table behind it: 71 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

Profile updated

Source
01

Chester Zoo

Giant otter. Chester Zoo.

The page saysThe biggest of all the otters, the Amazon's "river wolf"
The source saysIt is the biggest of all the otters
The page saysthe Amazon's "river wolf"
The source saysIn the waters of the Amazon, the giant otter is known as the 'river wolf' due to its large, razor sharp teeth and muscular body.
The page saysswamps, flooded forests
The source saysSwamps, flooded forests and rivers These areas provide proximity to the fish that giant otters eat.
The page saysin South America
The source saysFOUND IN South America Giant otters can be found near the Amazon, Orinoco and La Plata River systems.
The page saysFish such as piranha, catfish, and perch
The source saysGiant otters primarily eat fish, such as perch, piranha and catfish.
The page saysplus crabs, snakes, and even small caimans and anacondas
The source saysThey will also eat crabs, snakes, and even small caimans and anacondas.
The page saysIn the waters of the Amazon, *Pteronura brasiliensis* is known as the "river wolf" for its large, razor-sharp teeth and muscular body.
The source saysIn the waters of the Amazon, the giant otter is known as the 'river wolf' due to its large, razor sharp teeth and muscular body.
The page saysIt is the biggest of all the otters
The source saysIt is the biggest of all the otters
The page saysaveraging 1.5 to 1.8 meters long
The source saysAVERAGE SIZE 1.5 - 1.8mNote: the source's own qualifier "AVERAGE SIZE" is kept as "averaging".
The page saysIts life span is 10 to 13 years
The source saysLIFE SPAN 10 - 13 years
The page saysthough in human care giant otters can live for up to 21 years
The source saysAlthough with human care they can live for up to 21 years.
The page saysSwamps, flooded forests, and rivers keep it close to the fish it eats
The source saysSwamps, flooded forests and rivers These areas provide proximity to the fish that giant otters eat.
The page saysa Fish Diet
The source saysGiant otters primarily eat fish, such as perch, piranha and catfish.
The page saysIt primarily eats fish such as perch, piranha, and catfish
The source saysGiant otters primarily eat fish, such as perch, piranha and catfish.
The page sayscan eat up to nine pounds of food a day
The source saysThey can eat up to nine pounds of food per day!
The page saysIt will also eat crabs, snakes, and even small caimans and anacondas.
The source saysThey will also eat crabs, snakes, and even small caimans and anacondas.
The page saysGiant otters live in family groups of up to 20
The source saysGiant otters are highly social animals that live together in family groups of up to 20 individuals.
The page saysmade up of a mated pair and their offspring of several generations
The source saysA family has a large home range and consists of a mated pair and their offspring of several generations.
The page saysLife on the Red List
The source saysIUCN red list status Endangered
The page saysGiant otters are hunted for their water-resistant fur and their meat
The source saysThey are hunted for their water-resistant fur and for their meat.
The page saysbetween 1950 and 1970, 20,000 otter pelts were exported from Peru alone
The source saysBetween 1950 – 1970, 20,000 otter pelts were exported from Peru alone.
The page saysThe trade in giant otter fur was banned in 1973, but the species is still under threat.
The source saysThe trade in giant otter fur was banned in 1973, but they are still under threat.
The page saysTerritory expansion, mining, and hunting are some of the factors causing their numbers to decrease
The source saysTerritory expansion, mining and hunting are some of the factors causing their numbers to decrease.
The page sayslogging and farming destroy their breeding sites, and mining poisons the rivers where they live with mercury
The source saysLogging and farming destroy giant otter breeding sites, and mining poisons the rivers where they live with mercury.
The page saysIn the Amazon it's known as the "river wolf" due to its large, razor-sharp teeth and muscular body.
The source saysIn the waters of the Amazon, the giant otter is known as the 'river wolf' due to its large, razor sharp teeth and muscular body.
The page saysThey eat small ones.
The source saysThey will also eat crabs, snakes, and even small caimans and anacondas.
The page saysGiant otters primarily eat fish like perch, piranha, and catfish
The source saysGiant otters primarily eat fish, such as perch, piranha and catfish.
The page sayswill also eat crabs, snakes, and even small caimans and anacondas
The source saysThey will also eat crabs, snakes, and even small caimans and anacondas.
The page saysdangerLevel: Medium
The source saysdue to its large, razor sharp teeth and muscular bodyNote: No cached source describes an attack on a person. The tier is the capability: a 34 kg carnivore with large, razor-sharp teeth can injure, and nothing supports High's 'dangerous when cornered or provoked'.

Source
02

National Geographic, Animal Facts

Giant Otter. National Geographic, Animal Facts.

The page saysRivers, creeks
The source saysIt lives only in the rivers and creeks of the Amazon, Orinoco, and La Plata river systems.
The page saysreaching up to 6 feet
The source saysSize : Up to 6 feet
The page saysNational Geographic gives its weight as 75 pounds (34 kilograms)
The source saysWeight : 75 poundsNote: 34 kg is the conversion of 75 lb (34.0 kg); the page gives no range, so none is added. The quote is the page's whole fact-box row for weight.
The page saysIt lives only in the rivers and creeks of the Amazon, Orinoco, and La Plata river systems.
The source saysIt lives only in the rivers and creeks of the Amazon, Orinoco, and La Plata river systems.
The page saysweightKg: 34
The source saysWeight : 75 poundsNote: 75 lb = 34.0 kg.

Source
03

San Diego Zoo Wildlife Alliance

Otter. San Diego Zoo Wildlife Alliance.

The page saysIt's the longest otter, at 4.9 to 5.9 feet (1.5 to 1.8 meters) long.
The source saysLength: Largest - giant otter Pteronura brasiliensis, 4.9 to 5.9 feet (1.5 to 1.8 meters)Note: family-wide page: only its giant otter row is cited. "Longest" is the page's "Largest" in its Length row.

Source
04

Animal Diversity Web, University of Michigan

Pteronura brasiliensis (giant otter). Animal Diversity Web, University of Michigan.

The page saysIt has few predators, though jaguars and pumas occasionally kill one.
The source saysPteronura brasiliensis has few predators, but occasionally it is killed by jaguars and pumas.

Source
05

Groenendijk et al. 2023

Groenendijk et al. (2023). Pteronura brasiliensis. The IUCN Red List of Threatened Species 2023: e.T18711A244867206.

The page saysThe IUCN lists the giant otter as Endangered.
The source saysEndangered A2cde+3ceNote: read by hand in Chrome on 2026-09-16 (iucnredlist.org refuses scripts): Endangered, 2023-1 amended version of the 2020 assessment. Corroborated by Chester Zoo's current page: "IUCN red list status Endangered".

Source
06

Mumm & Knörnschild 2014

Mumm & Knörnschild (2014). The Vocal Repertoire of Adult and Neonate Giant Otters (Pteronura brasiliensis). PLoS ONE.

The page saysan adult vocabulary of 22 distinct calls
The source saysWe found a vocal repertoire with 22 distinct vocalization types produced by adults
The page saysplus 22 distinct adult calls
The source saysWe found a vocal repertoire with 22 distinct vocalization types produced by adults
The page saysThe group cooperates in breeding and territorial defense, though it is still unclear whether giant otters truly hunt cooperatively.
The source saysThe group cooperates in breeding and territorial defence [43], [46], [50], [51], whereas it is still unclear, whether giant otters truly show cooperative hunting or not
The page saysScientists who recorded five wild and three captive groups
The source saysWe recorded five wild and three captive giant otter groups.
The page saysfound 22 distinct call types made by adults and 11 in the babbling of newborns
The source saysWe found a vocal repertoire with 22 distinct vocalization types produced by adults and 11 vocalization types within the babbling bouts of the neonates.
The page saysa comparison with other otters suggested the giant otter is the most socially and vocally complex species
The source saysA comparison within the otter subfamily suggests a relation between vocal and social complexity, with the giant otters being the socially and vocally most complex species.

Source
07

Mumm & Knörnschild 2017

Mumm & Knörnschild (2017). Territorial choruses of giant otter groups (Pteronura brasiliensis) encode information on group identity. PLOS ONE.

The page saysincluding group choruses that might help mob caimans and jaguars
The source sayspredators like caiman and jaguars might be actively mobbed [...] with the help of ear-piercing screams and group choruses
The page saysA Family Chorus
The source saysLong-range screams are not only produced by one individual at a time ('single screams') but also by multiple group members simultaneously, resulting in a highly conspicuous 'group chorus'.
The page saysWhen several group members give long-range screams at once, the result is a "group chorus"
The source saysLong-range screams are not only produced by one individual at a time ('single screams') but also by multiple group members simultaneously, resulting in a highly conspicuous 'group chorus'.
The page saysthat can be heard over several hundred meters
The source saysgroup choruses and single screams are loud vocalizations that can be heard over a distance of several hundred meters
The page saysPredators like caimans and jaguars might be mobbed with the help of these screams and choruses
The source sayspredators like caiman and jaguars might be actively mobbed [...] with the help of ear-piercing screams and group choruses
The page sayswhich can also help giant otters avoid direct encounters with unfamiliar, potentially hostile otters
The source saysthese conspicuous vocalizations can also help giant otters to avoid direct encounters with foreign and potentially hostile conspecifics
The page sayswhose group members scream together
The source saysScreams are not only produced by single giant otters but also by several group members simultaneously, resulting in a highly conspicuous group chorus
The page saysin a chorus heard over several hundred meters
The source saysgroup choruses and single screams are loud vocalizations that can be heard over a distance of several hundred meters

Source
08

Timm-Davis, DeWitt & Marshall 2015

Timm-Davis, DeWitt & Marshall (2015). Divergent Skull Morphology Supports Two Trophic Specializations in Otters (Lutrinae). PLOS ONE.

The page sayshas jaw leverage that should favor speed
The source saysThis species possessed the smallest MA temporalis and MA masseter, which should maximize jaw velocityNote: MA is mechanical advantage, the jaw's leverage; the paper's own hedge "should" is kept.
The page saysJaw leverage that should favor speed over force
The source saysThere is a mechanical tradeoff in any lever system that constrains jaws to either maximize force or velocity, but not both simultaneouslyNote: with the giant otter's own values: "This species possessed the smallest MA temporalis and MA masseter, which should maximize jaw velocity".
The page saysLong Jaws
The source saysGiant river otters possessed the greatest total skull length, palate length, rostrum length, and mandibular length compared to any other otter species investigated.
The page saysA study of 150 skulls from four otter species
The source saysOne hundred fifty skulls from four otter species (2 mouth-oriented and 2 hand-oriented) were examined.Note: 150 is the source's "One hundred fifty".
The page saysfound the giant otter had the greatest total skull length, palate length, and mandibular length of the four
The source saysGiant river otters possessed the greatest total skull length, palate length, rostrum length, and mandibular length compared to any other otter species investigated.
The page saysA jaw can maximize force or velocity, but not both at once.
The source saysThere is a mechanical tradeoff in any lever system that constrains jaws to either maximize force or velocity, but not both simultaneously
The page saysThe giant otter had the lowest mechanical advantage for its temporalis and masseter jaw muscles, which should maximize jaw velocity
The source saysThis species possessed the smallest MA temporalis and MA masseter, which should maximize jaw velocityNote: MA is the paper's abbreviation for mechanical advantage.
The page saysan advantage for catching fast, elusive prey with its canines
The source saysan advantageous trait for capturing fast, elusive prey with the canines

Source
09

Davenport 2010

Davenport (2010). Aid to a Declining Matriarch in the Giant Otter (Pteronura brasiliensis). PLoS ONE.

The page saysoxbow lakes
The source saysthese lakes are highly productive habitats, and are preferred core territories for giant otters
The page saysproductive oxbow lakes are preferred core territories
The source saysthese lakes are highly productive habitats, and are preferred core territories for giant otters
The page saysOne family that fed its matriarch
The source saysshe begged from other family members 43 times over 41 contact hours and received food 11 timesNote: one group in one park; the page names no other case.
The page saysIn Manu National Park, Peru, one family had been observed every year for several years
The source saysThe otter group had been observed annually for several years and all members were known individually.
The page saysManu National Park, Peru
The source saysa habituated group of giant otters (Pteronura brasiliensis) in Manu National Park, Peru
The page saysin 2007, its matriarch Cacao appeared to be in physical decline
The source saysIn 2007, the breeding female of the group failed to reproduce and appeared to be in physical decline.Note: the name is in the Results: "Cacao, the matriarch, was first seen in Salvador in 1998".
The page saysShe still caught medium and small fish but failed to catch even one large fish that year.
The source sayswhile Cacao caught medium and small fish, she failed to catch even one large fish in 2007
The page saysShe begged from other family members 43 times over 41 hours of observation and received food 11 times.
The source saysshe begged from other family members 43 times over 41 contact hours and received food 11 times
The page saysCompared with 2004 to 2006, most help and food transfers that year went from young to old rather than from old to young.
The source saysComparisons with 2004–2006 demonstrate that the family's behavior in 2007 constitutes a role-reversal, in which the majority of assistance and prey transfers accrued from young-to-old rather than from old-to-youngNote: "most" is the source's "the majority of".
The page saysOne wild family did.
The source saysHere I report observations of multiple forms of assistance to the declining matriarch of a habituated group of giant otters (Pteronura brasiliensis) in Manu National Park, Peru.
The page saysA biologist in Peru's Manu National Park watched a declining matriarch beg from other family members 43 times over 41 hours of observation and receive food 11 times.
The source saysshe begged from other family members 43 times over 41 contact hours and received food 11 times
The page saysCompared with 2004 to 2006, most help and food in 2007 went from young to old rather than from old to young.
The source saysComparisons with 2004–2006 demonstrate that the family's behavior in 2007 constitutes a role-reversal, in which the majority of assistance and prey transfers accrued from young-to-old rather than from old-to-youngNote: "most" is the source's "the majority of".

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.