---
title: "What the sources say about the Giant River Otter | AnimalTracks.wiki"
description: "71 claims from the Giant River Otter profile, each beside the words of the source that backs it."
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---

# What the sources say about the Giant River Otter (*Pteronura brasiliensis*)

> 71 claims from the Giant River Otter profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Giant River Otter](https://animaltracks.wiki/animals/giant-river-otter/)

## Giant otter. Chester Zoo.

https://www.chesterzoo.org/animals/giant-otter/

| The page says | The source says |
| :--- | :--- |
| The biggest of all the otters, the Amazon's "river wolf" | It is the biggest of all the otters |
| the Amazon's "river wolf" | In the waters of the Amazon, the giant otter is known as the 'river wolf' due to its large, razor sharp teeth and muscular body. |
| swamps, flooded forests | Swamps, flooded forests and rivers These areas provide proximity to the fish that giant otters eat. |
| in South America | FOUND IN South America Giant otters can be found near the Amazon, Orinoco and La Plata River systems. |
| Fish such as piranha, catfish, and perch | Giant otters primarily eat fish, such as perch, piranha and catfish. |
| plus crabs, snakes, and even small caimans and anacondas | They will also eat crabs, snakes, and even small caimans and anacondas. |
| In the waters of the Amazon, *Pteronura brasiliensis* is known as the "river wolf" for its large, razor-sharp teeth and muscular body. | In the waters of the Amazon, the giant otter is known as the 'river wolf' due to its large, razor sharp teeth and muscular body. |
| It is the biggest of all the otters | It is the biggest of all the otters |
| averaging 1.5 to 1.8 meters long | AVERAGE SIZE 1.5 - 1.8m (note: the source's own qualifier "AVERAGE SIZE" is kept as "averaging".) |
| Its life span is 10 to 13 years | LIFE SPAN 10 - 13 years |
| though in human care giant otters can live for up to 21 years | Although with human care they can live for up to 21 years. |
| Swamps, flooded forests, and rivers keep it close to the fish it eats | Swamps, flooded forests and rivers These areas provide proximity to the fish that giant otters eat. |
| a Fish Diet | Giant otters primarily eat fish, such as perch, piranha and catfish. |
| It primarily eats fish such as perch, piranha, and catfish | Giant otters primarily eat fish, such as perch, piranha and catfish. |
| can eat up to nine pounds of food a day | They can eat up to nine pounds of food per day! |
| It will also eat crabs, snakes, and even small caimans and anacondas. | They will also eat crabs, snakes, and even small caimans and anacondas. |
| Giant otters live in family groups of up to 20 | Giant otters are highly social animals that live together in family groups of up to 20 individuals. |
| made up of a mated pair and their offspring of several generations | A family has a large home range and consists of a mated pair and their offspring of several generations. |
| Life on the Red List | IUCN red list status Endangered |
| Giant otters are hunted for their water-resistant fur and their meat | They are hunted for their water-resistant fur and for their meat. |
| between 1950 and 1970, 20,000 otter pelts were exported from Peru alone | Between 1950 – 1970, 20,000 otter pelts were exported from Peru alone. |
| The trade in giant otter fur was banned in 1973, but the species is still under threat. | The trade in giant otter fur was banned in 1973, but they are still under threat. |
| Territory expansion, mining, and hunting are some of the factors causing their numbers to decrease | Territory expansion, mining and hunting are some of the factors causing their numbers to decrease. |
| logging and farming destroy their breeding sites, and mining poisons the rivers where they live with mercury | Logging and farming destroy giant otter breeding sites, and mining poisons the rivers where they live with mercury. |
| In the Amazon it's known as the "river wolf" due to its large, razor-sharp teeth and muscular body. | In the waters of the Amazon, the giant otter is known as the 'river wolf' due to its large, razor sharp teeth and muscular body. |
| They eat small ones. | They will also eat crabs, snakes, and even small caimans and anacondas. |
| Giant otters primarily eat fish like perch, piranha, and catfish | Giant otters primarily eat fish, such as perch, piranha and catfish. |
| will also eat crabs, snakes, and even small caimans and anacondas | They will also eat crabs, snakes, and even small caimans and anacondas. |
| dangerLevel: Medium | due to its large, razor sharp teeth and muscular body (note: 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'.) |

## Giant Otter. National Geographic, Animal Facts.

https://www.nationalgeographic.com/animals/mammals/facts/giant-otter

| The page says | The source says |
| :--- | :--- |
| Rivers, creeks | It lives only in the rivers and creeks of the Amazon, Orinoco, and La Plata river systems. |
| reaching up to 6 feet | Size : Up to 6 feet |
| National Geographic gives its weight as 75 pounds (34 kilograms) | Weight : 75 pounds (note: 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.) |
| It lives only in the rivers and creeks of the Amazon, Orinoco, and La Plata river systems. | It lives only in the rivers and creeks of the Amazon, Orinoco, and La Plata river systems. |
| weightKg: 34 | Weight : 75 pounds (note: 75 lb = 34.0 kg.) |

## Otter. San Diego Zoo Wildlife Alliance.

https://animals.sandiegozoo.org/animals/otter

| The page says | The source says |
| :--- | :--- |
| It's the longest otter, at 4.9 to 5.9 feet (1.5 to 1.8 meters) long. | Length: 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.) |

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

https://animaldiversity.org/accounts/Pteronura_brasiliensis/

| The page says | The source says |
| :--- | :--- |
| It has few predators, though jaguars and pumas occasionally kill one. | Pteronura brasiliensis has few predators, but occasionally it is killed by jaguars and pumas. |

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

https://doi.org/10.2305/iucn.uk.2023-1.rlts.t18711a244867206.en

| The page says | The source says |
| :--- | :--- |
| The IUCN lists the giant otter as Endangered. | Endangered A2cde+3ce (note: 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".) |

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

https://doi.org/10.1371/journal.pone.0112562

| The page says | The source says |
| :--- | :--- |
| an adult vocabulary of 22 distinct calls | We found a vocal repertoire with 22 distinct vocalization types produced by adults |
| plus 22 distinct adult calls | We found a vocal repertoire with 22 distinct vocalization types produced by adults |
| The group cooperates in breeding and territorial defense, though it is still unclear whether giant otters truly hunt cooperatively. | The 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 |
| Scientists who recorded five wild and three captive groups | We recorded five wild and three captive giant otter groups. |
| found 22 distinct call types made by adults and 11 in the babbling of newborns | We found a vocal repertoire with 22 distinct vocalization types produced by adults and 11 vocalization types within the babbling bouts of the neonates. |
| a comparison with other otters suggested the giant otter is the most socially and vocally complex species | A 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. |

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

https://doi.org/10.1371/journal.pone.0185733

| The page says | The source says |
| :--- | :--- |
| including group choruses that might help mob caimans and jaguars | predators like caiman and jaguars might be actively mobbed [...] with the help of ear-piercing screams and group choruses |
| A Family Chorus | Long-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'. |
| When several group members give long-range screams at once, the result is a "group chorus" | Long-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'. |
| that can be heard over several hundred meters | group choruses and single screams are loud vocalizations that can be heard over a distance of several hundred meters |
| Predators like caimans and jaguars might be mobbed with the help of these screams and choruses | predators like caiman and jaguars might be actively mobbed [...] with the help of ear-piercing screams and group choruses |
| which can also help giant otters avoid direct encounters with unfamiliar, potentially hostile otters | these conspicuous vocalizations can also help giant otters to avoid direct encounters with foreign and potentially hostile conspecifics |
| whose group members scream together | Screams are not only produced by single giant otters but also by several group members simultaneously, resulting in a highly conspicuous group chorus |
| in a chorus heard over several hundred meters | group choruses and single screams are loud vocalizations that can be heard over a distance of several hundred meters |

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

https://doi.org/10.1371/journal.pone.0143236

| The page says | The source says |
| :--- | :--- |
| has jaw leverage that should favor speed | This species possessed the smallest MA temporalis and MA masseter, which should maximize jaw velocity (note: MA is mechanical advantage, the jaw's leverage; the paper's own hedge "should" is kept.) |
| Jaw leverage that should favor speed over force | There is a mechanical tradeoff in any lever system that constrains jaws to either maximize force or velocity, but not both simultaneously (note: with the giant otter's own values: "This species possessed the smallest MA temporalis and MA masseter, which should maximize jaw velocity".) |
| Long Jaws | Giant river otters possessed the greatest total skull length, palate length, rostrum length, and mandibular length compared to any other otter species investigated. |
| A study of 150 skulls from four otter species | One 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".) |
| found the giant otter had the greatest total skull length, palate length, and mandibular length of the four | Giant river otters possessed the greatest total skull length, palate length, rostrum length, and mandibular length compared to any other otter species investigated. |
| A jaw can maximize force or velocity, but not both at once. | There is a mechanical tradeoff in any lever system that constrains jaws to either maximize force or velocity, but not both simultaneously |
| The giant otter had the lowest mechanical advantage for its temporalis and masseter jaw muscles, which should maximize jaw velocity | This species possessed the smallest MA temporalis and MA masseter, which should maximize jaw velocity (note: MA is the paper's abbreviation for mechanical advantage.) |
| an advantage for catching fast, elusive prey with its canines | an advantageous trait for capturing fast, elusive prey with the canines |

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

https://doi.org/10.1371/journal.pone.0011385

| The page says | The source says |
| :--- | :--- |
| oxbow lakes | these lakes are highly productive habitats, and are preferred core territories for giant otters |
| productive oxbow lakes are preferred core territories | these lakes are highly productive habitats, and are preferred core territories for giant otters |
| One family that fed its matriarch | she begged from other family members 43 times over 41 contact hours and received food 11 times (note: one group in one park; the page names no other case.) |
| In Manu National Park, Peru, one family had been observed every year for several years | The otter group had been observed annually for several years and all members were known individually. |
| Manu National Park, Peru | a habituated group of giant otters (Pteronura brasiliensis) in Manu National Park, Peru |
| in 2007, its matriarch Cacao appeared to be in physical decline | In 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".) |
| She still caught medium and small fish but failed to catch even one large fish that year. | while Cacao caught medium and small fish, she failed to catch even one large fish in 2007 |
| She begged from other family members 43 times over 41 hours of observation and received food 11 times. | she begged from other family members 43 times over 41 contact hours and received food 11 times |
| Compared with 2004 to 2006, most help and food transfers that year went from young to old rather than from old to young. | Comparisons 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-young (note: "most" is the source's "the majority of".) |
| One wild family did. | Here 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. |
| A 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. | she begged from other family members 43 times over 41 contact hours and received food 11 times |
| Compared with 2004 to 2006, most help and food in 2007 went from young to old rather than from old to young. | Comparisons 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-young (note: "most" is the source's "the majority of".) |