US States Which Allow You to Keep a Capybara As a Pet.

Before you seriously consider keeping a capybara as a pet, can I urge you to do the research. Too many capybaras kept as pets die prematurely or end up in refuges. I have written a number of blogs on Capybara Welfare and different aspects of keeping a capybara as a pet, including Diet, Pool Size, How to Treat a Pool to Make It Safe for a Capybara, etc. PLEASE READ THESE. I give links to these blogs at the end of this blog. Please also read these 2 blogs:

A Pet Capybara: Should I Have One?

Pet Capybara FAQs. The Questions People Always Ask:

Below are two of the best links giving information about which States might allow you to keep a capybara as a pet.

Io eating his cecotropes 2012

Six month old Io eating his cecotropes. Cecotropes are not poo. Cecotropes are higher in protein, and have a different consistency, and eating them increases the nutritional content of the food capybaras eat

However, even within States regulations often vary. Counties, cities and even neighbourhoods may also have their own laws about keeping capybaras as pets. You should also check Covenants, Conditions and Restrictions (CC and R’s) in your area. There may also be regulations included in the Deeds to your home. You may also need to get the agreement of other residents in your area.

Your local Wildlife Fish and Game government department will have more information. Wildlife Fish and Game is also the Department you may have to contact to apply for your license/permit to keep a capybara as a pet. They will want to inspect your property, and if permission is granted there will be further inspections at regular intervals to check on the welfare of your capybara and his/her habitat.

Wildlife Fish and Game in Henderson, Nevada, admitted that they did not know much about keeping capybaras as pets when they issued the permit to keep capybaras as pets to friends of mine. Having read my blogs, they realised how little they knew and became much stricter in issuing permits! (My friends would still have got their permit, but several other would-be capybara pet owners were turned down, which hopefully saved a few capybaras from an unhappy life.)

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Bear in mind that the information on the Internet about keeping wild animals as pets in different States tends to be general in nature, so you should contact your local authorities for the precise regulations that pertain to keeping a capybara in the place where you live. For example, some websites suggest you cannot keep any wild animal as a pet in Washington State, but in reality this refers primarily to dangerous wild animals. In Washington State you may be able to keep a capybara as a pet depending on the area, particularly if your area does not have sidewalks. However, you may also have to get the agreement of other residents in the area.

The following states generally allow people to keep capybaras as pets: Arizona, Arkansas, Texas, Florida, Indiana, Nevada, Washington, North Carolina; I have also been told Tennessee and parts of New York state. You will still need to get a licence/permit to keep a capybara as a pet in most of the states.

It is much more difficult to get permission to keep a pet capybara in Europe, where Animal Welfare Laws tend to be much stricter. Many European countries do not permit the keeping of wild animals as pets. In some countries you may be able to keep a capybara as a pet if you fulfil very stringent requirements; this may be the case in France and Poland. Keeping a capybara as a pet is illegal in Italy. (A friend of mine in Italy rescued a badly injured nutria who had escaped from the farm where he was being reared for his fur.) Nutrias were brought to Italy for the fur trade and some escaped. There are also escaped wild nutria in Paris in the river Seine, and other parts of France.

These are the best links I could find:

Born Free USA is a National Animal Advocacy nonprofit organisation:

Summary of State Laws Relating to Private Possession of Exotic Animals       (

This is another useful link:

Remember, not all the information given on the Internet is necessarily entirely accurate.

PLEASE, PLEASE, PLEASE, read these blogs if you are seriously thinking of keeping a capybara as a pet. Capybaras are exceptionally sensitive and emotional (they have very high emotional intelligence) and suffer stress much more than dogs. They suffer extreme “separation anxiety” (if they are bonded with a human) every time the human leaves the home. Listening to the plaintive cry of a pet capybara (who I was pet sitting) every time his “owner” left home was heartbreaking, and the experience will haunt me for the rest of my life.

1.     What Should I Feed My Pet Capybara?:

2.      Protect Your Capybaras and Guinea Pigs from Power Cords and Electric Cables:

3.  Pet Capybara Pool Size. What Size Pool Does My Capybara Need?:

4.  Capybara Health Warning: it might be potentially dangerous to let your capybara swim in a chlorinated swimming pool designed and intended for human use.

5.  Some plants are toxic for capybarasCapybaras, Beware of Toxic Plants, Chemicals and Poisonous Animals like Scorpions and Snakes. Humans, Remove These from Your Land, Garden and Yard. カピバラに対して毒性である植物。有毒化学物質。危険な動物 – ヘビ、クモ、サソリ

6. Critical Care for Capybaras. Capybara Health Care. This Could Save the Life of Your Capybara.

I have written many other blogs which are useful for anyone thinking of keeping a capybara as a pet, at my blog site “Capybara World” on WordPress:

Loving, Affectionate, Compassionate Donut, One of My Favourite Capybaras. 長崎バイオパークで私のお気に入りのカピバラの1つ、愛情深く、愛情深く、思いやりのあるドーナツ 愛心,深情,富有同情心的甜甜圈,長崎生物園中我最喜歡的水豚之一

Donut Comes from The Best Capybara Bloodline at Nagasaki Bio Park

The most interesting, intelligent, compassionate capybaras at Nagasaki Bio Park descend from Donguri and Momiji, Donguri’s daughter, with Toku as their father.

Momiji was the best capybara mother, tirelessly watching over her pups, protecting them, teaching them and always acceding to their demands for milk, unlike many capybara mothers who are much less diligent. Momiji invested so much in her babies, it would be a tragedy if her daughter, Aoba, was not allowed to breed.

Momiji had 4 pups: 3 male pups, Nina, Choco and Donut, and a female, Aoba. Nina was born in February 2012, Choco and Donut were born in July 2013, and Aoba was born in June 2014.

ドーナツはチョコの兄弟です。 祖母はどんぐり、母はもみじ。 青葉は彼の妹です。 モミジは現在、日本で最も古いカピバラの1つです。 12歳半以上。 私が知っている最古のカピバラは17歳でした(フランスとアメリカで)。

甜甜圈是喬科的兄弟。 他的祖母是Donguri,母親是Momiji。 青葉是他的妹妹。 Momiji現在是日本最古老的水豚之一。 超過12 1/2歲。 我所知道的最古老的水豚已經活到17歲(在法國和美國)。

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Donut looking so cute with a smile on his face

Donut is a very loving, affectionate and sensitive capybara. He is Choco’s brother but in some ways he could not be more different. Where Choco is fearless, Donut is very cautious and nervous. When he was younger, if Hinase, the leader of the herd, approached, Donut would jump up and move away, whereas Choco would completely ignore Hinase unless she became aggressive. Choco has inherited his grandmother, Donguri’s, peaceloving nature and avoids aggression. Donut quite naturally wanted to be the dominant male capybara in the herd and realised that Choco was his main rival. He often challenged Choco, and Choco usually turned his back and walked away.

I love Donut dearly, and I know he was simply acting out of instinct, but it was heartbreaking to see Choco being injured. Eventually the two brothers had to be separated, with Choco and Donut taking it in turns to spend part of the day in a separate enclosure. Then for some completely unjustifiable and tragic reason the Biopark decided to sell Choco, and send him to China. Choco was the most popular capybara in the herd, with people coming from all over Japan, and all over the world, to meet him. Many people cried and were absolutely heartbroken. Nagasaki Bio Park refused to say where Choco had gone (i.e. to which zoo in China Choco had been sent), which made matters even worse, and more devastating for his legion of fans. For more about Choco please see my blogs:

What happened to Choco Capybara:

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Donut on the right and Choco on the left, the brothers nose to nose stand-off

Donut has inherited many of his mother, Momiji’s, characteristics, including her excellent parenting skills! After Zabon gave birth, Donut looked after Zabon’s pups, when they were allowed into the main enclosure, often helped by Momiji.  Zabon was quite weak and when the chief capybara keeper interfered with Zabon’s relationship with her pups, Zabon lost interest. Donut and Momiji took over.

Every morning Donut waited by the gate to the separate enclosure where Zabon and the babies had spent the night, ready to follow them and guard them when they were released into the main enclosure. He and Momiji often prevented the pups from falling in the pond. (Baby capybaras can swim from birth. The problem is that sometimes they cannot get out of a pond or river because the banks are too steep. There are a few places where baby capybaras can climb out of the pond at the Biopark, but these babies had not yet learnt where these places were. When Choco, Donut and Macaroni were released into the main herd, six weeks after they were born in July 2013, mother Momiji took them on a grand tour of the pond showing them all the easy places to climb out of the pond, and the best place to rest if they wanted to escape from the visitors; there is a part of the pond to which visitors do not have access.)

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Donut looks after Zabon’s babies, just 10 days old

As a yearling, Donut was at the bottom of the hierarchy and fearful of being attacked at the food trough. So he waited until all the other capybaras had finished eating, and often did not get enough to eat. Choco, ever resourceful, went into the monkeys’ house and ate the monkeys’ breakfast! Choco also frequently, and blatantly, helped himself to the bamboo which had been cut to sell to the visitors, and raided the bamboo store. Choco never went short of food! Donut by contrast never stole food. Momiji and sister Aoba, steal bamboo from time to time, but never so blatantly, and on the scale that Choco did!

Over the years Donut rose in the hierarchy and is now the most powerful capybara in the herd. However, he seems to have inherited his grandmother’s wise, peaceloving nature and avoids conflict with herd members, only challenging if he is hungry. If Hinase challenges Donut, Donut wins. However, unlike Hinase who always asserts her authority, Donut seems to go out of his way to be friendly to potential future rivals like Prune. Prune is another neutered male capybara, who might one day challenge Donut for his dominant position in the herd. I have seen Donut nuzzle Prune under the chin, which surprised me since Donut is much more senior in the hierarchy. I would expect Prune to be currying favour with Donut by nuzzling Donut under the chin, and not the other way round. Capybaras love to be nuzzled under the chin.

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Donut and Choco sleeping peacefully together on Capuchin Island. Donut is closer to the camera

Donut can be very aggressive to any capybara who has been separated from the herd, and is in a separate enclosure. This may be, in part, because as the most senior male capybara in the herd, he feels he has to protect the boundaries of his enclosure, in order to protect the herd. Donut learned this behaviour as a baby, standing beside Momiji when she tried to fight with Yuzu through the bars of the fence, after Yuzu had been separated from the herd. While baby Donut watched Momiji being aggressive, Choco had no interest in Momiji’s aggressive behaviour.

Donut frequently tried to fight with Toku, the previous breeding male who was separated from the herd, through the bars of his fence. However, he doesn’t seem to fight so much with Kona, who replaced Toku as the breeding male. Kona came from a petting zoo in Osaka and loves to be petted. However, at Nagasaki Bio Park he doesn’t get petted and he exhibits signs of extreme stress. Petting releases the hormone “oxytocin” which induces relaxation; this is something Kona desperately needs. I have asked the capybara keepers and the Chief Animal Keeper at the Biopark to pet Kona, but they refuse. I don’t understand this, and I wonder if they are trying to break Kona’s spirit. It seems to me that Kona has decided to avoid extra stress by not engaging aggressively with Donut. It is also possible that Kona’s personality differs from that of Toku, and does not make Donut feel aggressive.

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Donut yawning with a sweet smile on his face

Donut spends a lot of time trying to fight with Ryoko through the bars of her fence. Ryoko had to be separated from the herd after she became very weak, following a C-section to deliver her pups, and was attacked by other capybaras. (For more on the circumstances surrounding Ryoko’s tragedy, see my blog:  ) Ryoko is one of the most intelligent capybaras in the herd and was destined to succeed her mother Hinase as leader of the herd. She is a very tough minded capybara, and seems to cope with the stresses of being separated from the herd by luring Donut over to provide entertainment, and relieve the boredom, with his aggression. To attract Donut’s attention, Ryoko will jump in her little pond making a great splash, or go running round and round her enclosure at great speed. This immediately attracts Donut’s attention and he comes running! Donut would often rather fight with Ryoko than eat bamboo; most capybaras would prioritise food.

Like his mother, Momiji, Donut is very slim, fit and athletic. You can see Donut running in the video below:

Donut is one of my favourite capybaras. He is very sensitive, emotional and affectionate, and will often come to me to be petted. He loves me running my foot gently along his tummy, or between his hind legs. One day, when I was very upset, Donut sensed my unhappiness and came over to me, and was very affectionate.

Kyushu can be very hot and humid in August with temperatures sometimes reaching 40°C, so my husband quite often has a nap in the afternoon, in the Capy stove hut, in the capybara enclosure. Seeing a lifeless human seems to worry Donut and he often comes over to check up on my husband to make sure he is all right. I imagine that, like me, Donut cannot understand how anyone could fall asleep in the presence of capybaras.

The bond between capybara family members, and between members of the herd is much stronger than many people realise, because it is often quite subtle. For example, although Donut is now much stronger than his mother Momiji, he still respects her, and will never challenge her for food.

Baby Donut being nibbled by Choco and Macaroni in the video below:

Some zookeepers in Japan seem to have a very different approach to capybara husbandry, and to the animals in their care, compared with European zookeepers. The zoo keepers looking after the capybaras at Nagasaki Bio Park change frequently and are often straight out of college, with the result that they have little experience, and no understanding of animals. A zoo keeper at a zoo in Fukuoka is on record as saying, very accurately: “Animal Welfare is not well understood in Japan. Most Japanese people do not understand animals”.

I was told by a Japanese zookeeper that, in Japan, most people become zookeepers because they like the outdoor life, not because they love animals. I know there are exceptions and I have one Japanese zookeeper friend who understands animals, and is an excellent zookeeper.

Due to this lack of understanding, the Biopark has recently focused on breeding female capybaras who will allow the keeper to handle her pups from birth, interfering with the bonding process between mother and offspring. No European zoo would allow this to happen.

The female capybaras who allow the keepers to handle their pups, tend to be those who are least popular with the herd, and therefore the least suitable female capybara to breed to. A European zookeeper would never choose such a female to breed to, as it goes against nature, and the natural order, and will undermine the unity of the herd.

Fortunately, “mother nature” stepped in, and Butter (the only female capybara chosen to mate in 2020) did not become pregnant.

Reproductive suppression is widely reported in social animals, including rodents. Sometimes, this is to control the number of capybaras in the herd. However, it can also be associated with cooperative breeding, whereby reproduction is not equally distributed among group members. It therefore makes sense, that the least appropriate female to breed, would experience reproductive suppression, i.e. not get pregnant, in favour of the most desirable female capybara in the herd, in this case Aoba. However, Aoba was prevented from breeding as she was not allowed into Kona’s enclosure. (The breeding male capybara, in this case Kona, is separated from the herd in order to control the number of babies born.)

Butter sometimes behaves a little oddly and does not follow the rules of the herd. Hinase seems to dislike Butter intensely, and frequently chases her. Momiji also dislikes Butter. Because Butter is not popular with the herd, she gravitates to humans. This behaviour is also seen with horses, wherein horses who are not popular with the herd, gravitate to humans.

It is a great loss that Donut and Choco had to be neutered. Now only Aoba can carry on this great bloodline.

Why Aoba Should Be the Next Female Capybara to Breed at Nagasaki Bio Park

It would be heartbreaking for Momiji if Aoba was not allowed to breed. Momiji invested so much in Aoba, letting her suckle for eight months, rather than the usual four months. Consequently Aoba grew into a very strong, healthy capybara. Momiji would be a fantastic grandmother.

It would be heartbreaking, and a tragedy for the herd, if Aoba was not allowed to breed.

I have all these behaviours on video.

An Amusing Account: When Donguri Gave Birth in 2008, at Nagasaki Bio Park. 日本語。どんぐりはもみじや楓を出産したときは

English translation of blog written by Nagasaki Bio Park staff in Japanese. All photographs by Nagasaki Bio Park.                               

When Donguri gave birth to her 3 pups, Momiji, Kaede and Akkun, on 10 September, 2008, she chose to have her babies on Capuchin Island, away from human intervention. She does not have a very high opinion of humans, and wanted to protect them and keep them away from the visitors, which is why she chose to have them on the island. She was most perturbed when the babies were removed from the island by the keepers, and taken to a special enclosure. She quickly followed them there.

This is a link to the original Japanese version written by Nagasaki Bio Park:

(I have kept some of the “Google translate” translations, as they give the flavour of the Japanese humour, and are easy to understand)

September 10, 2008, three capybara pups are born! “Donguri (Acorn)”is the mother, “Takeshi” is the father. (Donguri means Acorn in English.)

These days (at least since 2012) the female capybaras who are about to give birth are put in a separate enclosure, with strings across the top, to protect the newborn pups from crows. Perhaps in 2008 the pregnant capybaras were allowed to give birth in the main enclosure with the rest of the herd. Or perhaps the keepers didn’t realise that Donguri was about to give birth. Donguri is a very large capybara.

Donguri gave birth during the night, and chose to have her pups on the largest of the three islands in the pond, known as “Capuchin Island”. In the wild, capybara mothers go somewhere quiet to give birth, slightly apart from the main herd, in an area with vegetation which will offer some protection from predators. In captive situations, some people separate pregnant capybaras shortly before they give birth, for fear that the male capybaras will attack the pups. However, in reality there is little evidence of infanticide in capybara herds, and it is very stressful for a mother capybara to be separated from her herd. All the capybara fathers I know, have been excellent fathers, very involved, and helping to look after their pups.

When the keepers arrived on the morning of 10 September, and discovered that Donguri had given birth, they set about moving the pups to a separate enclosure for their safety. Donguri was not happy about this!

Donguri: “I hear a noise! What is happening by the pond?”

“Oh no, the keepers have arrived, and are watching me. I wonder what they want?”

Keeper: “First, in order to capture the babies, you must separate the mother and babies, for the time being.”
Keepers: “. ーDonguri, Horahora To~tsu I have gone a little beyond”
Donguri: “I am not happy with what you are doing. I cannot forgive you Fuga~tsu (angry)”
“I am usually a very calm, laid-back capybara. However, this time I will intimidate the keepers with a fierce bark. “
Splash!  Reluctantly I have been forced into the pond!”

Donguri stays in the pond. She watches intently to see what the keepers are doing to her pups, on Capuchin Island. She doesn’t want to go to an isolated enclosure, separated from the herd.

Donguri: “My babies, are they all right I wonder …”

Keeper: “Finally, we begin to capture the baby capybaras. We must not injure the babies.”

The rest of the herd vocalises loudly: “We must intimidate the keepers to protect Donguri and her babies”

Keeper: “Right! I have managed to catch one baby. This is very difficult, the pups move very quickly”.

“Finally, I have managed to catch the other two babies. If I don’t give them back to Donguri soon……”

Keepers: “Donguri, wait! Hurry hurry!

Keeper: “The 3 babies are captured. Everyone is safe. The crows did not cause any injuries, fortunately. The babies are very energetic, so I think they were born some time ago, perhaps just after the Biopark closed yesterday.”

Babies: “Where are we? Where is our mother?”

Donguri goes into this separate enclosure first, isolated from the herd. “Such excitement! This reunion.”
Donguri:. “Well I’m glad everyone is safe and sound. We are lucky! Now I will climb the rocky hill to get away from the humans. Let’s go!”

With that, the babies follow their mother, Donguri, up the mossy, rocky slope. “We are all very healthy!”

“Hey, wait Yo!”

たかさん– Taka san

The Capybara Scandal

I am trying to stop capybaras becoming the next “must have” exotic pet craze, and suffering the same fate as potbellied pigs, when they become large and difficult to handle.

I was talking to a lady who runs an Animal Refuge in Indiana who already has 2 capybaras who she rescued. She said there was a growing number of people buying female capybaras in order to mate them, and make money out of selling their babies. She expects to have many more capybaras who need to be rescued, because there are now so many breeders, and so many people who want a cute pet capybara.

When capybaras are portrayed as “cute” (dressed in clothes, hats and sunglasses) you create a market for pet capybaras among people who are not really interested in capybaras, but just love their cuteness. These people have no understanding of a capybara’s needs, and no desire to spend time doing the necessary research.

Capybaras are happiest as part of a herd in their natural habitat. These capybaras are in the Llanos of Colombia

People need to know that pet capybaras are sometimes aggressive. As they grow older and bigger, capybaras become very powerful. They have very sharp teeth (the Amerindians, in South America, use capybara teeth as weapons, attached to poles). Not many people want a pet who can cause painful, even serious, injuries.

Please see my blog: A Pet Capybara: Should I Have One?

The leading breeder of capybaras stopped selling capybaras to the public as pets, about 8 years ago, because so many pet capybaras suffered, often dying prematurely or ending up in animal refuges.

This is the perfect enclosure for a capybara: lots of grass and a large pond. Photo by Martin MurmelTier Hees

Many pet capybaras die prematurely due to tooth problems, inappropriate diet and stress.

A friend, who runs an animal refuge, reminded me of the craze for potbellied pigs, not so long ago. When these potbellied pigs grew larger, many were abandoned and ended up in refuges. The same is beginning to happen with capybaras.

Capybaras are very sensitive emotionally; they are intelligent, sentient beings who can think and feel.

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If you look in Ran’s eyes you can see how frightened he is

I was heartbroken to learn that during the extreme cold spell in February 2021, many pet capybaras suffered frostbite. This indicates that most people who get pet capybaras should not. This has happened before. Over the years I have been horrified to hear of capybaras suffering frostbite in North America. If I had capybaras living outside in extreme weather conditions, I would usher them into my house, and if necessary cover them with blankets. No capybara should suffer frostbite.

I find it very depressing that people who say they care about capybaras like to see capybaras dressed in clothes. No one who dresses a capybara in clothes should have one of these remarkable animals.

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If you look at her eyes you can see how frightened she is. It is very stressful for any animal to live in a constant state of fear

It seems that most people cannot see life from an animal’s perspective. Like everyone who understands animals, I don’t understand why people like seeing capybaras in dresses. One of the reasons people love capybaras is they are so cute – naked!

People should know that capybaras don’t like wearing clothes. This should not come as a surprise to anyone who understands animals. I have witnessed first-hand how uncomfortable and unhappy capybaras are in clothes. Being made to wear clothes also interferes with the relationship between a pet capybara and their owner. The capybara is confused why someone they love is doing this to them.

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Capybaras love rolling in mud and it keeps their skin healthy

I came across a website, by accident, which advertised capybaras for sale. These were capybaras who had outgrown their “baby” cuteness. They varied in age from about nine months to 3 years. The way in which they were described by the people selling them was heartbreaking. One seller described his capybara as “Sold as is, with defects”, as if he was selling a used car. Another advertised his capybara as: “Cannot be handled”; I wondered what had caused this capybara to become so unhappy and aggressive. Another seller described the capybara he was selling as “Suitable for display” as though this sensitive, living being was an inanimate object with no feelings or needs. I was in tears thinking about the unhappy lives humans had created for these loving animals. And I was appalled at the lack of compassion, concern or morality of the people selling these unwanted capybaras.

I was in conversation recently with a man who wanted to keep a capybara as a pet. He was convinced he could give the capybara a better life than the capybara would experience in the wild! Research has shown that wild animals kept as pets suffer much more stress than if they were living in the wild, in their natural habitat.  I was horrified at this man’s lack of understanding and arrogance. He obviously had no understanding whatsoever of animals, and unfortunately was not interested in learning.

Capybaras do not like to wear clothes. Dressing a pet capybara causes stress and interferes with the bond between the capybara and the human, as the capybara cannot understand why the human is doing this to him
Capybaras do not like to wear clothes. Dressing a pet capybara causes stress and interferes with the bond between the capybara and the human, as the capybara cannot understand why the human is doing this to him

It is well known that the market for “cute” animal photos and videos is detrimental to Animal Welfare. In some countries it encourages people to buy wild animals as pets when in fact these wild animals are totally unsuited to becoming pets and usually suffer. It also results in an increasing number of zoos, often very small and cramped, which house cute animals in prisonlike conditions. These animals suffer immense stress in small, unsuitable enclosures, often with concrete floors. In the case of capybaras, who are semi aquatic, their water source is a small plastic tub often barely larger than the capybara himself, when they need a body of water large enough for them to swim and play.

Capybara cafes should be banned. A cafe is a very stressful and unsuitable habitat for a wild animal. Animals in captivity should always be able to express their natural behaviours and have some control over their lives. Capybaras need to have access to grazing and a pond 24/7. Nobody who understands animals would want to see a capybara, or any other wild animal, in a cafe.

We humans cause so much suffering to the animals we call “cute”. Capybaras, and all other species, are so VERY MUCH MORE than cute.

For more on this topic see my blog: “Animal Manifesto, Animals Are Real Not Cute”

Anyone who understands animals and cares about capybaras will be very concerned about the welfare of the growing number of capybaras being bought as pets.

There is an increasing number of people breeding capybaras for sale as pets to meet this demand. The result is capybaras suffer, and end up in refuges.

Some of the people who say they love capybaras, understand animals and care about the welfare of capybaras. Other people who say they like capybaras, just like their cuteness and want them as entertainment, but have no understanding of, or interest in, their welfare. Unfortunately, I believe the majority of people who say they like capybaras, are in the latter category. I believe this is partly because most people cannot see life from an animal’s perspective. My mission is to prevent capybaras from suffering by helping people to understand the needs of these remarkable, sentient beings.

A Capybara Tells Her Story.

Hello, I am Hinase, leader of the herd at Nagasaki Bio Park.

I rule by intimidation! The rest of the herd knows that as I approach they should show respect by sitting up and becoming tense and alert. Much the same as a sergeant major expects the troops to “stand to attention” when he arrives.

Even my best friend, Momiji, knows to do this. I bully her from time to time but she knows my bad moods are short lived. It’s very frustrating living as a captive capybara at the hands of humans, with no access to grass so I am unable to eat whenever I’m hungry. I don’t understand humans at all. Some capybaras seem to understand them but they are usually the capybaras who the rest of the herd don’t like, so they gravitate towards humans.

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Momiji has a different approach to humans. She knows we capybaras are superior to humans and she has no respect for humans. She refuses to be controlled by humans and would rather starve than beg for food.

I have very expressive eyes as you can see in this video. I always have a twinkle in my eye when I am about to chase or intimidate a disobedient capybara. I enjoy wielding my power!

The expression in my eyes reflects my amazement and disbelief that any capybara in the herd would risk upsetting me!

You Can Read a Capybara’s Emotions in Their Eyes

One of my jobs as ruler is to ensure that all the other capybaras in the herd know how to behave. Sometimes the youngsters begin to become too aggressive, as happened with Milk and Prune, so I had to teach them how to behave as junior members of the herd!

I completely understand capybaras and how to rule them, if only I had the same understanding and control of humans!

We used to have a male capybara in the herd, who we could breed with. He was always the centre of attention. There was much less aggression in those days because of his presence, since we spent our time trying to attract him rather than fighting amongst ourselves.

This all changed in 2013 with the birth of the males Syu, Choco, Donut and Macaroni. Tragically Syu died and Macaroni moved to another zoo with his mother Ayu.

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I am hoping to be fed!

I wasn’t happy that Choco and Donut remained in the herd. They should have left when they were yearlings, as they are too closely related to our females to be allowed to breed.

Don’t ask me about neutering. It is something which should be done to humans!

Anyway it seems Choco and Donut can’t father babies, which is a relief. But they mate with Maple and Butter which makes me very angry.

Choco is absolutely fearless so I have to bite him to get his respect. Donut is a good boy and becomes suitably nervous as I approach, getting up and moving away.

Actually just in the past 2 years Donut has become stronger and more powerful than me, so I try not to challenge him as he would win. Fortunately he seems to have inherited our grandmother, Donguri’s, wisdom and will often move away from food as I approach, unless he is very hungry.

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I am watching with great interest! Zabon has been allowed into Toku’s enclosure to mate with him. All the herd has come over to watch. This is very exciting but also frustrating as I should be the one mating with Toku. The humans only allowed one capybara to mate this year. They should have consulted me!

Momiji’s daughter, Aoba, understands the rules. She wants me to accept her so she nuzzles me under the chin and nibbles my ear which I love. Not many adult capybaras would do this. In return I let her join us in the Onsen. In Donguri’s day, Donguri would let almost all the capybaras into the Onsen and it became very crowded. Momiji and I like to have the Onsen to ourselves so we guard the entrance and sit under the shower, which is the favoured spot.

My nemesis is Butter. She doesn’t understand the rules and even though she knows I hate her, and frequently attack her, she still comes over to try to eat my food, or join us in the mud bath! She shouldn’t be mating with Choco and Donut, a rule which all the other female capybaras understand, except Butter’s mother Maple. Sometimes it’s tiring having to keep chasing her but it’s the only way to teach her.

For some reason some humans seem to like Butter, and to my horror she was chosen to breed in 2020 when it should have been Aoba. Fortunately, Butter did not become pregnant. Probably, “Mother Nature” prevented her from becoming pregnant, understanding that Butter was the last female in the herd who should be allowed to breed. Mother nature is much wiser than the zookeepers at the Biopark.

I’m not sure who will succeed me. It should have been my daughter, Ryoko, but one of the keepers ran very fast towards Ryoko when she was very heavily pregnant and terrified her, so she jumped up and ran away as fast as she could. When she sat down her body heaved 3 times and she had a miscarriage. She ended up having to have a cesarean (C-section) to deliver her babies, only one of whom survived, Ryosuke. Ryoko didn’t eat for 2 weeks and became very weak. When she was introduced back into the herd (she had been in a separate enclosure after giving birth) she was attacked and so had to be separated again. She has been separated from the herd ever since.

I would like Aoba to succeed me. I worry that Milk is hiding her aggression for the moment but might fight to become leader in the future.

I find it interesting that my favourite human likes the same capybaras who I like. She understands the problem we have with Butter. It is a pity she is not our zookeeper.

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This is the best position in the Onsen, in this wooden tub under the shower so naturally this is where I should be. Unfortunately Maple got their first so I had to evict her!


My favourite human says: “One thing Hinase taught me was that capybaras are much more aware of everything going on around them including what the humans are up to, then people realise. After Donguri died, Hinase began coming over to me. I was slow to realise that she knew exactly who I was and assumed that I had been Donguri’s slave and benefactor because Donguri was leader of the herd. Now that she, Hinase, had become leader of the herd, she assumed I would treat her the way I had treated Donguri. I never interacted with Hinase when Donguri was alive so I find it very illuminating that she knew exactly who I was and what she wanted from me. Most people have no idea that capybaras have this intelligent understanding and awareness of life going on around them.

In fact most humans completely underestimate our intelligence.

Why Capybaras Need Water カピバラが水を必要とする理由 為什麼水豚需要水

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Hinase, leader of the herd, takes a nap in the pond in the heat of August to thermoregulate, i.e. to cool down.

Capybaras are semiaquatic, with partially webbed paws. They have 3 toes on their hind paws and 4 toes on the front paws.

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Aoba and Madoka play in the large pond at Nagasaki Bio Park

Capybaras need water to thermoregulate (to keep cool and keep their body temperature down when it is hot) and to escape from predators and other dangers. They also use water to play in, and to defecate and mate in. Capybaras can defecate and mate on dry land as well.

In Colombia during the dry season capybaras spend about 4 hours a day in rivers and ponds thermoregulating to keep from overheating.

Capybaras are not obsessed with water. It is this sort of statement which makes ethologists rail against anthropomorphism.

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Baby brothers Choco and Donut play in the pond. Their mother is Momiji and the grandmother is Donguri

Capybaras like humans are individuals with different preferences. Some capybaras spend longer in water than others. Some capybaras feel the heat or the cold more than others.

Capybaras are fascinating animals. They are so much more than just cute. However, like heiresses, they often attract the wrong sort of people for the wrong reasons. I find it heartbreaking that many people really are not interested in learning accurate information about capybaras. Capybaras deserve better than that.


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I love the expression on Choco’s face as he mates with Maple. Choco is a neutered male so no babies

カピバラは、体温調節(体温を冷たく保つ)し、捕食者や危険から逃れるために水を必要とします。 彼らはまた、水を使って遊んだり、交尾したり、排便したりします。カピバラは、乾燥した土地でも排便して交尾することができます。


水豚需要水來調節溫度(使體溫保持涼爽),並擺脫掠食者和危險。 他們還使用水玩耍,交配和排便。水豚也可以在旱地上排便和交配。

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Toku mates with Zabon. Gestation period for capybaras is 5 months and Zabon gave birth to 2 pups, Madoka and Ko
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Capybaras prefer to defecate in water. This little pond is a favourite area for the capybaras to do their poos. These two are Maple and Yuzu

How Capybaras Communicate with People

Many, perhaps most, people do not truly understand animals. From my experience it is an innate ability, something you are born with, and relates to how sensitive a person you are. To understand animals you also have to immerse yourself in their lives, and observe every nuance of their relationships with other members of their species, and their behaviours. I have recorded these behaviours on video.

I find it disappointing that scientific research sometines expresses surprise at supposedly “newly discovered” behaviours in animals, when I have observed these behaviours being exhibited by capybaras. I am certain many other species also exhibit these behaviours.

Françoise Wemelsfelder has done groundbreaking research showing that people who spend a great deal of time with, and work with, a particular species, accurately identify the behaviours and emotions of that species.

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Romeo and Tuff’n, on hearing sounds of human activity in the kitchen, appear! Tuff’n points his nose in the direction of the food he would like to be given.

In recent research involving 11 Kangaroos who lived in captivity, 10 of the kangaroos would gaze intently at researchers when they wanted help. 9 of the kangaroos would look alternately at the human and then at the (in this case) box with food, which they were unable to open. I am disappointed when the scientists say “wild species are not really expected to behave as these kangaroos do, and that’s why it’s surprising”.

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Romeo stands beside the table where the peanut dispenser is kept, and looks imploringly at me

Capybaras use their noses to point at something they want. If they want something to eat, they may also use mimicry, in this case chewing motions, sometimes subtly moving their lips, sometimes more flagrantly moving their lips, all the while fixing you with a powerful stare, or pointing their nose at the food source. If they don’t get what they have asked for, they may escalate their behaviour by using their teeth to nibble you, or the receptacle containing the food. They will also do this if you are not responding quickly enough to their more subtle initial request! Some capybaras, habituated to humans, seem to have learnt that humans find capybara tongues very cute, so as part of their request for food some capybaras will stick out their tongue, as they have found this extra layer of cuteness results in them being offered food.

You can see this behaviour in the following video with Tuff’n:

Donguri was the only capybara I fed so she came to look upon me as her benefactor. The first year I visited Nagasaki Bio Park, the male capybara, Yasushi, lived with the herd. When I returned the following year, the new male, Toku, had been put in a separate enclosure so the female capybaras, including Donguri, could not gain access to him. On my very first day, Donguri lead me over to Toku’s enclosure and pointed her nose up at the handle of the gate, obviously asking me to open the gate for her so she could go in and be with Toku. She knew humans were able to open gates and as I was a human, who cared about her, she assumed I would open the gate. Heartbreakingly for me, I didn’t have the authority to open the gate; something Donguri could not have understood. When I didn’t respond (I have always wondered if she thought I was stupid) she walked around the enclosure and back to the entrance gate, and again pointed her nose up at the handle. When I still didn’t open the gate for her, I felt my relationship with her changed. I had let her down and we both understood that.

On another occasion, Donguri injured her foot and could barely walk. She hobbled over to the room where sick capybaras are treated (I am impressed that Donguri understood that going to this sick room, which is very rarely needed for sick or injured capybaras, could communicate to the keeper that she needed treatment), and sat in the entrance looking out, waiting for a keeper to notice her and treat her injury. It was not long before her unprecedented behaviour had attracted the attention of the keeper who called the vet. The vet prescribed an anti-inflammatory painkiller, meloxicam. One morning a few days later, when she was still in pain, Donguri limped round and round in circles in the centre of the capybara enclosure, right in front of the bamboo stall where the keeper stood. The obvious explanation for this “never seen before” behaviour was that she was trying to attract the attention of the keeper to show that she needed more pain medicine, i.e. another meloxicam pill. (Donguri was so clever that I would not put it past her to exaggerate her limp in order to emphasise her message to the keeper).

Donguri was 10 years old at the time she exhibited these behaviours. She was leader of the herd. Capybaras, like humans, vary as to how intelligent they are. The most intelligent capybaras I have met, Choco, Ryoko, Donguri, Toku and Tuff’n, all exhibits behaviours which would impress and surprise people unfamiliar with rodent behaviour.

Donguri leg injury waits hospital room 2015

Donguri stands at the entrance to the room where sick capybaras are kept and waits for the keepers to notice her

You can see this behaviour in the following video:

A few months later, Donguri ate too many leaves of a bush whose leaves are slightly toxic. I was told the capybaras often ate a few leaves from this bush so I believe it had some medicinal properties. Donguri, however, had eaten too many leaves and began to feel unwell. She walked over to the Onsen, where soothing cold water was running, and stood under the shower and vomited (You can see the video of poor Donguri vomiting, towards the end of this blog). People have told me that capybaras cannot vomit but this is not true.

She then went and sat on a soft bed of leaves looking very sorry for herself. I sat beside her. After a while I offered her a pellet. She took the pellet eagerly but immediately spat it out. The obvious explanation for this behaviour was that she had taken the pellet eagerly, thinking it was a medicine pill, but on discovering that it was not what she had expected, she spat it out instantly.

Most people find it very difficult to give their pets, or the animals in their care, medicine. Donguri was extremely intelligent and must have worked out over the years that the keepers were able to help capybaras in distress, often by giving them medicine.

Donguri feeling better leg injury 2015 August 26

One afternoon I was talking to a travel agent from Taiwan in the capybara enclosure. We had been talking for quite a long time, when I happened to notice Donguri glowering at me from across the enclosure. She obviously thought I had been talking far too long! She had decided it was time for me to give her some attention and some bamboo! Donguri had a very powerful aura and it was not the first time she had fixed me with her powerful look to attract my attention and indicate she wanted something.

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People who live with pet capybaras will be very familiar with the behaviours capybaras use to communicate with humans. If Romeo or Tuff’n want food they will go over to the food receptacle, and point their noses towards the food. They may vocalise, or even use their teeth by nibbling the human, to attract the attention of their human and inject some urgency into their request. The food might be in the refrigerator, on the worktop in the kitchen, in the drawer of a coffee table in the living room, or a number of other places. Wherever the food they want is kept the capybaras will do everything in their power to communicate their desire for that food to the human. Within a few seconds of anyone going into the kitchen, Romeo and Tuff’n will miraculously appear, noses pointing in the direction of the food they want!

If Tuff’n wants peanuts, he lifts up the metal bowl into which Marvin puts his peanuts, and lets it fall softly onto the sofa. If this gentle demand has no effect, Tuff’n tosses the bowl a little higher so that it makes more noise when it falls. If this also fails to result in his peanuts appearing, Tuff’n tosses the bowl high into the air, so that it falls on the hard floor making an extremely loud clattering sound. (You can see this behaviour in the video below).

Capybaras living as pets also learn many words and phrases pertaining to the important things in their lives, and of course their names. For example Romeo and Tuff’n understand the difference between “inside the house” and “outside the house”. They understand “let’s go to the neighbour’s yard”, many food items, words like bath, grass, be good, potty pan and “go potty”. These are just some of the words and phrases Romeo and Tuff’n understand. Several people living with capybaras even think they have learnt how to speak one or 2 human words like “corn” or “milk”!

In this video Donguri vomits after eating too many toxic leaves. She walked to the Onsen and stood under the cool shower. She vomited many times but unfortunately my novice cameraman did not capture it all, and some of the time he was filming too much in close-up

I have several friends who are ethologists and have published research papers on capybara behaviour. I also have friends who are zookeepers and have worked with capybaras. What I find disappointing is that the zookeepers I know understand animals, animal behaviour, and the behaviour of the individual animals in their care, in a way that the ethologists I know do not. There are of course exceptions. Some ethologists spend a lifetime studying a particular species, for example Joyce Poole who has spent a lifetime studying elephants in Kenya. These ethologists really do understand the species they have spent so much time with. Other ethologists have spent a lifetime studying wolves, dolphins and orcas. These ethologists are often apologetic when they admit that the animals they have spent a lifetime studying do indeed have emotions!

Françoise Wemelsfelder has done groundbreaking research showing that people who spend a considerable time with a particular species, accurately identify the behaviour and emotions of the animals they are so familiar with.

Anthropomorphism is considered the greatest sin for many ethologists as if only humans experienced emotions! All mammals are descended from a common ancestor and thus share evolutionary continuity of inherited characteristics. Emotions evolved early in mammalian evolution. Humans and rodents shared a common ancestor about 70 million years ago. In my experience many capybaras are more sensitive emotionally than many humans. This may in part be due to their superior olfactory intelligence. Capybaras need to be sensitive to the emotions of other capybaras in their herd, particularly more senior capybaras, to avoid being attacked. If I am injured or upset in the company of a capybara, that capybara will pick up on my emotion, where many humans will not, and be extra affectionate.

Tuff'n kitchen hopeful July 2020

I particularly like the ethologist who studies pumas in North America, who says: “I study pumas, I think about pumas, I watch videos of pumas and I dream about pumas”. He obviously loves his subject and is obsessed with pumas. I can completely relate to this in my fascination with capybaras, their intelligence, their emotional sophistication and sensitivity, their resourcefulness and the way they, like most rodents species, are extremely affectionate and rewarding to study and be with.

Giant Rodents of South America Roedores gigantes de América del Sur カピバラの巨大な祖先水豚巨祖先

Imagine a capybara the size of a huge, male buffalo!

The largest rodent discovered so far is the massive Josephoartigasia Monesi, who was about the size of a bull buffalo (and much bigger than a 2-year-old Hereford bull – a Hereford bull only weighs about 700 kg!) and weighed about 1000 kg, with a very powerful bite force. Isostylomys laurillardi is thought to have been nearly as large.  Arazamys castiglionii weighed about 800 – 900 kg, smaller than Josephoartigasia Monesi and Isostylomys, but larger than Phoberomys; they were almost the size of a buffalo.

For reference: Pleistocene: 2.58 million years ago – 11,700 years ago, ended with the Ice Age. Pliocene: 5.333 million years ago – 2.58 million years ago. Miocene: 23.03 million years ago – 5.333 million years ago. Oligocene: 33.9 million years ago – 23.03 million years ago. Tertiary: 65 million years ago – 2.588 million years ago. Quaternary 2.6 million years ago into the present.

Phoberomys compared to human size and capybara

Size comparison between human, capybara and the genus Phoberomys. Phoberomys only weighed about 700 kg. Josephoartigasia Monesi was much larger and weighed 1000 kg

This is an overview of some of the many species of giant rodent who roamed South America during the Miocene, Pliocene and Pleistocene epochs, which lasted from 23 million years ago until the start of the last Ice Age, 11,700 years ago. Most of these giant rodents lived between 9 – 2 million years ago.

Palaeontologists believe there may have been over 50 species of giant rodent, but when the fossil evidence consists of only one or two fragments of mandible or skull (the bone most likely to survive over millions of years), or a tooth, it can be challenging to identify a species! Teeth survive for thousands, even millions, of years because of the strength of the enamel covering the teeth which is 97% mineral making teeth stronger than bones. Teeth and fragments of skull or mandible, are often the only fossil evidence that palaeontologists have when trying to identify different species of these long extinct giant rodents. Thus the different morphology and size of the teeth, and differing features of fragmentary pieces of skull or mandible, are crucial clues when identifying long extinct species.

Rodents appear in the fossil record in South America at least 31.5 million years ago, during the very early Oligocene.  The earliest caviomorph fossils have been found in Peru and dated to the late Oligocene. Capybaras are caviomorph rodents; the Caviomorpha clade is a subgroup of hystricognath (see paragraph below) rodents. South America was separated from other landmasses during most of the Tertiary, so evidence is lacking as to how rodents reached South America. Hystricognaths originated in Asia, but the South American rodents probably arrived from Africa by raft. The ancestors of most of today’s South American rodents, including capybaras, probably appeared between the middle and late Miocene. These giant rodent lineages in South America went extinct over 1 million years ago, some millions of years ago, with only the capybara alive today as the largest extant rodent. Hydrochoerus hydrochaeris, the most numerous and well-known of the two species of modern-day capybara, weighs on average about 50 to 60 kg, and is about the size of a large dog.

The Hystricognath rodents are an Infraorder of rodents distinguished from other rodents by the bone structure of their skulls. There are 18 families within the Hystricognathi, divided into 2 Parvorders, the Caviomorpha and the Phiomorpha. Capybaras are representatives of the Family Caviidae in the Parvorder Caviomorpha. Caviomorpha are mostly found in South America, with a few species in North America and the Caribbean. The Phiomorpha are found in the Old World.

A Clade is a group believed to include all the evolutionary descendants of a common ancestor.

Rodents are the most abundant group of living mammals. They also vary enormously in size. The smallest, about the size of a pygmy mouse, weighs only a few grams, while the largest, the extinct giant rodent Josephoartigasia Monesi weighed about 1000 kg. Rodents are also one of the most diverse mammals in South America, with over 160 species in total, either living today or extinct species. Today’s rodents include arboreal (tree dwellers), gliding rodents, fossorial (adapted to digging and living primarily but not exclusively underground), cursorial (adapted specifically to run; i.e. can run fast or maintain a constant speed over a long distance) and semi aquatic rodents. During the Tertiary rodents’ range of body size and physical characteristics was wider than today.

Some scientists have suggested these giant rodents may have gone extinct because they were not fast enough to outrun predators, and too large to dig burrows to hide in. Climate change may also have contributed to their demise.

Other extinct giant rodents include: the genus Eumegamys who weighed about 800 – 900 kg, and was a similar size to a hippopotamus. Phoberomys burmeisteri, believed to be the largest of this genus. Phoberomys Pattersoni thought to have weighed about 700 kg, and Phoberomys insolita (although Phoberomys insolita may have been a sub adult Phoberomys pattersoni) thought to have weighed about 400 kg. These predate Josephoartigasia Monesi and lived during the late Miocene in modern day Venezuela. Telicomys gigantissimus, the size of a small rhinoceros, about 2 meters long and with a weight of about 500 kg. and about 70% of the size of Phoberomys pattersoni.  Neoepiblema Acreensis, weighed about 80 kg. (See below for more about these giant rodents)

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Artist’s impression of Josephoartigasia Monesi, who was the size of a massive bull buffalo and weighed about 1000 kg

In 1987, the almost complete skull of Josephoartigasia Monesi was discovered in modern day Uruguay on the coast of the Rio De La Plata, in the San José formation. Based on the strata of the San José formation in which the J Monesi fossil was found, J Monesi lived 4 – 2 million years ago, during the Pliocene and early Pleistocene.

J Monesi is believed to have lived in a lowland forested, wetland habitat such as a delta or estuary. By identifying the diet of an extinct species (see below) scientists are able to speculate on the type of habitat the species lived in based on the vegetation it foraged. J Monesi shared its habitat with giant ground sloths, and predators such as enormous flightless “terror birds” sparassodonts, short faced bears and sabre toothed tigers.

Another feature of J Monesi that is especially interesting are its teeth. J Monesi had enormous, incredibly powerful, chisel -shaped incisors, an adaptation which allowed these incisors to be successfully used in hierarchy battles between males to ensure access to females and breeding rights, and in defence against predators. J Monesi may also have used their enormous incisors for digging in the same way that an elephant uses its tusks. These incisors were able to resist much greater forces than the molars, powered by the masticatory muscles, could generate. The molars are believed to have been used to masticate tough vegetation with forceful bites. Josephoartigasia Monesi’s diet probably consisted of grasses, aquatic plants and the bark of trees and bushes. As large mammals they would have been able to utilise these coarse, low quality food resources which much smaller species would not have been able to digest.

Representatives of the Dinomyidae family frequently had incisors which were able to resist much greater forces than their molars.

Scientific Classification: Josephoartigasia Monesi    Kingdom: Animalia Phylum: Chordata Class Mammalia Order: Rodentia Suborder: Hystricomorpha Infraorder: Hystricognath Family: Dinomyidae Genus: Josephoartigasia Species: Josephoartigasia Monesi

It can be challenging to make an accurate identification of different extinct rodent species as palaeontologists are often working from scant fossil remains, consisting of only a few fragments of mandible or skull (the bone most likely to survive) or a tooth. Some fossils which were thought to represent different species have been reassessed as representing juveniles, sub adults and adults of the same species. Some of these mega rodents had a unique, and complicated tooth morphology which changed as they aged (as is the case with capybaras). This change accounts for some of the erroneous designations of fossils, which were initially thought to represent different species’, but are now considered to be representatives of the same species, but of different ages. With other species the size of the teeth did not grow or change as the animal developed from being a juvenile to an adult. This means that the juvenile and the adult had the same sized teeth and were not different species.

Likewise, it can be difficult to gauge the size of the animal, and make size comparisons between different extinct species, unless the identical parts of the respective bodies are found. For example, the body size for Phoberomys pattersoni is based on parts of the fore limb and hind limb, and these were compared with this species closest living relative, the Pacarana. In the case of Josephoartigasia Monesi an almost complete skull was found. Although J Monesi is known only from this 1.7 foot (just over half a meter) long skull, this provided enough fossil evidence to indicate that this was a new species and the largest rodent who ever lived. To arrive at a body mass for J Monesi this skull was compared with several other living rodent species.

There are two methods scientists use to identify the diet of prehistoric species. Where fossil evidence is available scientists can investigate the preserved contents of the gut and faeces, both inside the body (cololites) and outside the body (coprolites). Scientists also study the chemical isotope in the fossil bones and teeth of these long extinct species, and compare this information with the carbon isotopes of different varieties of plants, to identify the animal’s diet. The isotopic signature of the food eaten by the animal is incorporated into the fossil bones and teeth, and remain stable over tens of thousands, even millions, of years. Teeth are often the only fossil remains of an extinct species which palaeontologists find, as teeth, being harder due to their enamel cover, survive better than bones. Palaeontologists also used the condition of Josephoartigasia Monesi’s teeth, the degree of wear and worn edges, pits and scratches, to assess the type of diet this species relied on.

The almost complete skull of J Monesi provided new information about the anatomy of extinct giant rodents of the Dinomyidae family who are primarily known from scant fossil evidence. The mandible is the largest and strongest facial bone, and forms the lower jaw, acting as a receptacle for the lower teeth. Together with the temporal bone, the mandible articulates on either side forming the temporomandibular joint. Scientists compared the mandible of J Monesi to that of its closest living relative, the Pacarana, to help them rebuild J Monesi skull. To simulate how J Monesi would bite at different locations along the jaw, scientists used a 3-D scan of this Pacarana mandible. J Monesi had an extremely powerful bite, estimated to be 3 times more powerful than a tiger’s bite, and comparable to modern day large crocodilians. The maximum bite force of its incisors has been estimated at close to 500 kg. The molars could only exert a maximum force of about 150 kg (about 300 lbs); thus the incisors were able to exert a much more powerful force.  J Monesi’s incisors were extremely strong and could resist greater forces than the masticatory muscles of the molars could generate, leading scientists to speculate that the primary role of these incisors was use in hierarchical combat, or defence against predators. The molars were primarily used to chew tough vegetation.

Palaeontologists are also able to estimate the bite force and how the stress of chewing might have affected the skull, by using an engineering technique, Finite Element Analysis. The maximum bite force of Josephoartigasia Monesi has been estimated at a maximum of 4165N, which is 3 times as powerful as a tiger.

Josephoartigasia Monesi’s closest living relative is the Pacarana, a critically endangered species at high risk of extinction, and the last surviving member of “their” family, the Dinomyidae. The Pacarana, Dinomys branickii, is a rare hystricognath rodent found only in small areas in South America. They are the second largest rodent species alive today; second only to the capybara, with a body length of about 80 cm (31 inches) and weighing about 15 kg (32 lbs). Pacaranas have a large head and a thick, furry tail. The name comes from the Tupi word meaning “false paca”, named because they look superficially similar to the paca. Due to the Pacarana’s low population levels, scientists had believed the animals were extinct. Like many species around the world today, they are vulnerable to human predation and habitat loss caused by human activities.

The Dinomyidae are a family of hystricognath rodents native to South America. Several extinct members of this family include the largest rodents who have ever lived, including the largest so far discovered, Josephoartigasia Monesi. The Dinomyidae are believed to have been large grazing mammals, the largest representatives of this family disappeared after the formation of the Isthmus of Panama about 3 million years ago, connecting North and South America. There were once many species in this group but now only the Pacarana survives.

The earliest fossils of the Dinomyidae family date from the middle Miocene, and fossils of this family have been found almost throughout South America. The clade reached its highest diversity (i.e. the greatest number of species of this family) in the late Miocene. The family is subdivided into 4 or 5 subfamilies: Potamarchinae (which includes the oldest known representatives of the family, possibly from the middle Miocene to the early Pleistocene). Gyriabrinae (late Miocene to late Pliocene). Dinomyinae (including the only living representative, Dinomyinae branickii – Pacarana). Eumegamyinae (late Miocene to the late Pliocene, and includes some of the largest members of the family). Tetrastylinae (late Miocene to late Pliocene. May be a subgroup of Eumegamyinae or Dinomyinae). It is not possible to determine the anatomy of these animals as there is insufficient fossil evidence: just a few fragments of mandible or skull, or a tooth.

Isostylomys laurillardi.

Artist’s impression of Isostylomys laurillardi, who was almost as large as Josephoartigasia Monesi

Isostylomys laurdillardi, is one of the largest species of giant rodent who lived during the Miocene epoch, 9 – 6.8 million years ago. This species is believed to have weighed almost 1000 kg.

In 2016 scientists found an almost complete and intact skull and part of the jaw of one adult, and the complete lower jaw, with all its teeth intact, and the right heel of a juvenile, of this species. The fossils were found in southern Uruguay in the Camacho Formation of the Rio de la Plata coastal region. Uruguay’s Camacho Formation was laid down during the late Miocene epoch, 12 million years ago – 5 million years ago.

The fossils were in exceptional condition, the best preserved fossils found so far for this species; previous finds amounted to only fragments of skull and the odd tooth. This allowed the scientists to compare tooth development between the adult and juvenile of this species. This led to a new understanding of the other species in this genus, which had previously only been studied from fragmentary fossil evidence.

These fossils, which represent an adult and juvenile, raise questions regarding the classification within their genus, Isostylomys, suggesting that fossils thought to indicate different, related species may in fact represent a single species, due to the way teeth are formed as the rodent ages.

The scientists discovered that the adult tooth shape emerged quite early in the rodent’s development, growing larger as the animal matured. By evaluating earlier fossils, considered to be the tooth forms for prenatal, juvenile and adult, they learned that adult tooth forms could vary in size. This led to an understanding that fossils which had been thought to represent related species, three species of Isostylomys, were in fact just one species of Isostylomys, representing different age groups, rather than different species.

As a result of this analysis, which showed that from a very young age the giant rodents were very similar to the adults, scientists have been able to learn how the world’s largest fossil rodents grow.

Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Suborder: Hystricomorpha
Infraorder: Hystricognathi
Superfamily: Chinchilloidea
Family: †Dinomyidae
Genus: †Isostylomys
Species:Isostylomys laurillardi

Arazamys castiglionii weighed about 800 – 900 kg, smaller than Josephoartigasia Monesi and Isostylomys, but larger than Phoberomys. They were almost the size of a buffalo. This species lived in the late Miocene. An incomplete skull of an adult was found in the Camacho Formation, in the San Jose Department, Uruguay. As with many other members of the Dinomyidae family, the molars are small relative to the large, powerful incisors and the estimated size of the skull.


Artist’s impression of Phoberomys pattersonii

Phoberomys pattersoni was a giant caviomorph rodent who lived during the late Miocene from about 9.0 – 6.8 million years ago. They lived in South America, in modern day Brazil, Argentina, Venezuela and Peru. Sedimentary evidence indicates they lived in coastal wetland habitats consisting of lagoons of shallow water separated from the coast by barriers of sand.

An almost complete fossil skeleton of Phoberomys pattersoni was discovered in 2000, in the Urumaco formation of the Orinoco River delta in Venezuela. The skeleton measured 3 meters (9.8 feet) with a 1.5 meter long tail (4.9 feet). This species was estimated to have weighed about 700 kg (1540 lbs). These size and weight estimates are reasonably accurate as almost an entire skeleton was discovered.

In appearance they may have looked more like a guinea pig than a rat. However, the humerus (which is part of the forelimb) gave a smaller estimate of body size than the femur (which is part of the hind limb), 436 kg as against 741 kg. This suggests that the hind limbs played a more important role in locomotion and weight support. The forelimbs may have been used to manipulate food as is the case with the Pacarama (Dinomyidae branickii) the only living member of this family.

The genus Phoberomys were herbivores, and like many rodent species they had high crowned premolars and molars indicating they were grazing animals i.e. grass eaters. The morphology of its teeth indicates that its diet was abrasive: coarse grasses and probably included aquatic grasses. Like the capybara, Phoberomys are believed to have been semi aquatic. Like Josephoartigasia Monesi, Phoberomys is a member of the family Diomyidae, whose only living relative, the Pacarana, is in danger of extinction.

Predators would have included large, very powerful birds like Brontornis and Kelenken, giant crocodilians. Sabre toothed marsupials would have preyed on the young.

As mentioned previously, reclassification sometimes occurs following further research, due to the challenges of identifying a species based on scant fossil remains, possibly only a few bones or teeth.

As an indication of this: the genus Phoberomys was thought, at one time, to consist of seven species, including: Phoberomys burmeisteri, Phoberomys praecursor, Phoberomys insolita, Phoberomys lozanoi and Phoberomys minima. However, a more recent study of Phoberomys fossils found in the Entre Rios province in Argentina, and dated to the late Miocene epoch, concluded that these were in fact just one species: Phoberomys burmeisteri. The study concluded that the differences among the fossils reflect different ages and stages of development of a single species. This gives an idea of just how difficult it is to accurately identify species from a very sparse fossil record.

Recent research also suggests that Phoberomys pattersoni and Phoberomys insolita may in fact be the same species. Phoberomys insolita had been estimated to be a little larger.

Scientific Classification Phoberomys pattersoni:    Kingdom: Animalia   Phylum: Chordata   Class: Mammalia   Order: Rodentia   Suborder: Histricomorpha   Family: Dinomyidae;   Genus: Phoberomys   Species: Phoberomys pattersoni

Phoberomys burmeisteri is believed to be the largest member of the Phoberomys genus who lived in the late Miocene epoch. The remains of this species was found in the Ituzaingó formation in Entre Rios province in Argentina.

Eumegamys is an extinct genus of giant rodent, about the size of a hippopotamus, of the family Dinomyidae. They lived during the late Miocene and Pliocene. Their fossil remains have been found in the Solimoes Formation in modern day Brazil, the Urumaco Formation in Venezuela, and the Ituzaingó formation in Argentina. It’s skull was about half a meter long (1.65 ft).

Telicomys gigantissimus lived in South America during the late Miocene and early Pliocene epochs (11.2 million – 5.3 million years ago). They were about the size of a small rhinoceros, about 2 meters long, and are thought to have weighed about 500 kg. They also were a member of the family Dinomyidae related to the Pacarana.

Eumegamys paranensis is an extinct species of giant rodent of the family Dinomyidae, who lived during the late Miocene and Pliocene in modern day Brazil, Venezuela and Argentina. It’s skull was 50 cm long. Evaluation of its cheek teeth, and the complexity of the crown, indicate that its diet consisted of coarse vegetation and demanding food items, and it was able to process more food each time it chewed (i.e. each masticatory cycle). Eumegamys paranensis fed on a varied diet, foraging close to the ground. It was probably a wide-ranging species, living near water and in gallery forests (narrow bands of forested area lining rivers) as would have been found in the Mesopotamic area of what is now the Paraná River system in north-east Argentina. This genus also lived in Brazil and Argentina.

Neoepiblema Acreensis is an extinct giant rodent, a relative of chinchillas, who weighed about 80 kg and lived about 10 million years ago in present-day Brazil in South America.

Using computerised tomography to look inside fossil skulls, scientists estimate that the brain of Neoepiblema Acreensis weighed just 47 g, meaning this rodent’s brain was unusually small compared to its body size. Two Neoepiblema Acreensis fossil skulls were studied, which gave an encephalisation quotient of 0.20 for one and 0.33 for the other. South American rodents alive today have an average encephalisation quotient above 1.05.

To compare the brain sizes of different animals of varying weights, scientists calculate a species’ “encephalisation quotient”, which measures the difference between the expected brain size based on body size, and the actual brain size for an animal of a given weight. Any value under 1 means that an animal’s brain is smaller than expected. The ratio between the size of the brain and the size of the body is thought to indicate intellectual ability.

This has led scientists to speculate that Neoepiblema Acreensis was not the brightest rodent. If this was indeed the case, the reason may have been that there were few predators to outwit so a larger brain was not worth the “cost” of maintaining a larger brain.

Critical Care for Capybaras. Capybara Health Care. This Could Save the Life of Your Capybara.

See below for the milk formula for baby capybaras. It is of course very important that any baby capybara who is not suckling (i.e. drinking his mother’s milk) is given the right formula of milk in order for the baby to thrive.

Please also see my blog about capybara diet. Many pet capybaras die prematurely because they are not given the right diet:

What Should I Feed My Pet Capybara?:

If you have a capybara who is not eating properly, or becoming very thin, this nutritional formula made by Oxbow, Critical Care for Herbivores, is recommended by a vet who specialises in treating capybaras. Your capybara may have tooth problems (which will need to be attended to) which makes chewing painful, or he might have an illness, or be recovering from surgery. This product has everything a capybara needs for optimum nutrition and health and recovery.

Remember that if your capybara has not been eating very much, his stomach will have shrunk. This means he will only be able to eat small quantities of food at any one time. You will need to keep offering him this formula, in small quantities, throughout the day to ensure he gets adequate nutrition.

As capybaras age, like humans, they may lose their appetites, or start to eat less. This will result in their stomach shrinking and they may only be able to eat a smaller amount of food at any one time; but they should be encouraged to eat more frequently to offset this. (This will not be necessary if the capybara has access to unlimited grazing or pellets 24/7 and continues to eat sufficient grass and pellets). This Critical Care formula is a good way to boost a capybara’s nutritional requirement.

Critical Care for Herbivores is a high protein, high energy, high fibre, easily digested powdered formula, with all the essential vitamins and minerals.

It is designed to be palatable so that your capybara enjoys it and wants to eat. It contains high-fibre Timothy hay to support proper gut physiology and digestion. It comes as a powder.

One friend found that his capybara did not like this formula when it was mixed with water, but he loved it when it was mixed with unsweetened almond milk. His capybara had already established a love of drinking unsweetened almond milk.

If your capybara is bonded with the human that human MUST give a capybara lots and lots of love and petting. You will need to spend much more time with him than you normally would otherwise we might lose the will to live, give up and die. Petting releases the hormone, oxytocin, and induces relaxation and plays a significant role in the bonding process. Your capybara will be very anxious during this time when he is suffering, and petting will help him relax. I cannot stress too strongly the importance of “being there” for your capybara at this critical time. Your love and time spent with the capybara could be the difference between life and death.

A Critical Care Formula in the form of a crunchy “biscuit”, is also available, and chewing it will be good for your capybara’s teeth.


“Developed with the assistance of top exotics veterinarians and nutritionists, Critical Care is the industry standard in recovery nutrition for herbivores with poor nutritional status resulting from illness or surgery.  Critical Care contains all the essential nutrients of a complete diet, as well as high-fiber timothy hay to support proper gut physiology and digestion.”

Critical Care for Herbivores, contains the following:

Timothy Grass Meal, Soybean Hulls, Soybean Meal, Wheat Germ, Xanthan Gum, Potassium Chloride, Salt, L-Ascorbyl-2-Polyphosphate (Vitamin C), Soybean Oil, Flaxseed, Magnesium Sulfate, Calcium Chloride, Papaya, Pineapple, Cane Molasses, Natural Apple Flavor, Natural Banana Flavor, DL-Methionine, L-Glutamine, Oat Groats, Wheat Middlings, Sodium Bentonite, Yeast Culture (dehydrated), Fat Product, Hydrolyzed Yeast, Inulin, Mixed Tocopherols (preservative), Choline Chloride, Vitamin E Supplement, Zinc Sulfate, Zine Proteinate, Niacin, Copper Sulfate, d-Calcium Pantothenate, Vitamin A Supplement, Manganous Oxide, Riboflavin Supplement, Biotin, Thiamine Mononitrate, Copper Proteinate, Sodium Selenite, Manganese Proteinate, Pyridoxine Hydrochloride, Folic Acid, Vitamin D3 Supplement, Cobalt Carbonate, Vitamin B12 Supplement, Calcium Iodate, Rosemary Extract

Guaranteed Analysis

  • Crude Protein (min) 17.00%
  • Crude Fat (min) 5.00%
  • Crude Fiber (min) 21.00%
  • Crude Fiber (max) 26.00%
  • Moisture (max) 10.00%
  • Ash (max) 10.00%
  • Calcium (min) 0.60%
  • Calcium (max) 0.80%
  • Phosphorus (min) 0.40%
  • Vitamin A (min) 10,000 IU/kg
  • Vitamin D3 (min) 900 IU/kg
  • Vitamin E (min) 190 IU/kg
  • Ascorbic Acid (Vitamin C) (min) 1,500 mg/kg

Calorie Content

  • Metabolizable Energy (calculated) 2,660 kcal/kg or 24 kcal/Tbsp

“Product Highlights:

  • Powdered formula mixes easily to desired consistency
  • Highly versatile – can be tube fed, assist-fed by syringe or spoon, or self-fed by bowl or as top dressing
  • High in fiber; low in carbohydrates
  • Contains readily-absorbable chelated minerals and beneficial prebiotics
  • No refined sugars, artificial preservatives or simple carbohydrates
  • High digestibility and palatability
  • Contains stabilized form of Vitamin C

Available in Anise and Apple-Banana flavors.

Sizes: 36g, 141g, 454g (anise); 141g, 456g (apple-banana)”

The Oxbow critical care formula is also available as a “Fine Grind“, with the same essential nutrition as Critical Care – Herbivore, but in a finer particle size.

Some recovery and emergency cases require added versatility when it comes to delivering critical nutrition.  Critical Care Herbivore – Fine Grind contains the same essential nutrition as Critical Care – Herbivore, but in a finer particle size made to flow easily through nasogastric feeding tubes as small as 5 Fr.  Because of its smaller particle size, Critical Care Herbivore – Fine Grind is ideal for use with small and young patients.

Sizes: 100g

Product Highlights:

  • Finer particle size than Critical Care
  • Powdered formula mixes easily to desired consistency
  • Highly versatile – easily flows through nasogastric tube and syringe
  • High in fiber; low in carbohydrates
  • Contains readily-absorbable chelated minerals and beneficial prebiotics
  • No refined sugars, artificial preservatives or simple carbohydrates
  • High digestibility and palatability
  • Contains stabilized form of Vitamin C


Another product which is very helpful for capybaras with less serious digestive problems is Bene-bac. Friends of mine use this whenever their capybaras become constipated or have very soft poos.

Friends of mine who live with 2 capybaras believe a product called ‘Bene-bac’ (which is a pro-biotic) is a lifesaver, and could have saved the life of their first capybara.  They use it whenever the capybara’s poos become softer and sausage shaped, rather than the encapsulated, olive shaped faeces which capybaras living in their natural habitat pass. Bene-Bac Small Animal Powder is a concentrated live culture of four common digestive bacteria found in the intestinal tracts of mammals. Bene-Bac is recommended any time an animal experiences stress from changing nutritional or environmental conditions. Contains 20 million CFU per gram of viable lactic acid producing bacteria. Powder formula is easy to mix with water.   It comes in 4 different types – the Bene-bac designed for rabbits is the correct one to use.

Constipation: Bene-bac can also be used to treat constipation. It is important to ensure your capybara drinks enough water and has access to fresh water to drink 24 hours a day. A healthy diet of unrestricted access to fresh grass should ensure a capybara does not become constipated. Chewing coarse grasses is essential for the health of capybara teeth.

Product Information

Bene-Bac® Plus Small Animal Powder is recommended any time an animal experiences changing nutritional or environmental conditions.

  • Contains seven fat-encapsulated, common microorganisms found in intestinal tract of small mammals
  • Provides help for changing conditions, including, but not limited to birth, breeding, post-surgery, antibiotic therapy, weaning, worming, showing, boarding and travel
  • Guaranteed 20 million colony-forming units (CFU) of viable bacteria per gram
  • Recommended as part of the management program for all animals subjected to adverse conditions
  • May be used for regular maintenance


Milk Formula For Baby Capybaras:

This is the only milk formula specifically formulated for baby capybaras. It has a higher protein content and fat content than other milk formulas for most other species. It comes from Australia.

Wombaroo Capybara Milk Replacer

DIRECTIONS FOR USE: To make 1 litre of milk mix 190g of powder with 870ml of preboiled warm water. Add about half of the water first, mix to a paste then make up to 1 litre with remaining water and mix thoroughly. An electric whisk can be used for mixing.

Feed Impact Colostrum Supplement to new-borns who did not receive sufficient maternal colostrum.

GROWTH & DEVELOPMENT: Typical birth weight is 1.5 – 2.0 kg. Average daily weight gain is about 50-100g per day until weaning at 3 months (approx. 8kg body weight)3 .


  • Protein 42%
  • Fat 24%
  • Carbohydrate 22%
  • Ash 6%
  • Moisture 4%
  • Metabolisable Energy (ME) 20MJ/kg

©Wombaroo Food Products, Dec 2017. 10 Oborn Rd, Mt Barker SA 5251



INGREDIENTS: Whole milk solids, whey protein, casein, vegetable oils, omega-3 and omega-6 fatty acids, stabilised vitamin C, vitamins and minerals.

TYPICAL COMPOSITION PER LITRE OF PREPARED MILK Protein83gVitamin E14mgFolic Acid1.0mgSodium500mg
Fat49gVitamin K1.0mgVitamin B1219μgMagnesium80mg
-Omega 31.4gVitamin C520mgBiotin80μgZinc5.1mg
-Omega 63.4gThiamine7.1mgCholine130mgIron5.5mg
Energy (ME)3.9MJNiacin29mgCalcium2.2gCopper0.8mg
Vitamin A470μgPantothenic Acid11mgPhosphorus1.6gIodine100μg
Vitamin D34.6gPyridoxine2.4mgPotassium1400mgSelenium25μg
TYPICAL ANALYSIS (Powder) Protein42%
Energy (ME)20 MJ/kg



The Lesser Capybara, Hydrochoerus isthmius. This species of capybara is less well-known then the larger, and much more numerous, Hydrochoerus hydrochaeris. 您知道水豚有2種嗎?這是較小的,數量少得多. カピバラには2種類あることをご存知ですか?この種は小さく、はるかに少ないです

There are 2 species of capybara, the larger Hydrochoerus hydrochaeris, which is the species we all know well, and Hydrochoerus isthmius also called the The Lesser Capybara. The 2 species look very similar. However, the Lesser capybara is smaller, with thicker and wider frontal bones. They have a slightly more angular head and a somewhat darker, brown coloured coat. The Lesser capybara weighs about 28 kg as against 40 – 60 kg for Hydrochoerus hydrochaeris. The 2 species of the genus Hydrochoerus live in habitats which rarely overlap.

Stanford 3

For an interval in the 20th century, the Lesser capybara, Hydrochoerus isthmius , was thought to be a subspecies of the larger Hydrochoerus hydrochaeris. However, genetic studies and studies of their anatomy in the mid-1980s, showed that the Lesser capybara was indeed a separate species. It’s karyotype (genetic sequence) has 2N equals 64 and FN equals 104. The karyotype of the larger Hydrochoerus hydrochaeris is: 2N equals 66 and FN equals 102.

The Lesser capybara breeds throughout the year and gives birth to 3 – 4 pups on average, as against up to 8 pups for Hydrochoerus hydrochaeris. The gestation period is 108 days for the Lesser capybara as against 150.6 days for Hydrochoerus hydrochaeris. The Lesser capybara pups at birth weigh about 1.1 kg (as against 1.5 kg for the larger capybara, Hydrochoerus hydrochaeris). As with Hydrochoerus hydrochaeris, the Lesser capybara can be diurnal or nocturnal, and social or solitary, depending on the season, the habitat and the pressure imposed by hunting.

Stanford to

There is not a great deal of information about the Lesser capybara, Hydrochoerus isthmius, as relatively few studies of this species have been done. Their conservation status is not known but they may be under threat in some of their traditional habitats. Their numbers are far smaller than Hydrochoerus hydrochaeris, the larger, well-known capybara. Their population status and current distribution in Colombia is unknown.

The Lesser capybara is under threat due to subsistence hunting and the destruction of its habitat. The gallery forests where they live are being cleared and the swamp lands, vital for this semiaquatic species, are being drained. The drainage of the swamp areas bordering the Magdalena River are having a particularly detrimental effect on their numbers.

Predators include jaguars and pumas on land and Cayman in water. Additionally, young capybaras are often attacked by snakes (boa constrictors), crab eating foxes, some birds like the caracara and black vultures.

The Lesser capybara is found in the Caribbean region, the northern end of the Pacific region and the inter-Andean valleys of the Cauca and Magdalena rivers.


If you want to meet a member of this species, this is where you might be able to find them: The Lesser capybara, Hydrochoerus isthmius, is found to the west of the Andes in Panama, Colombia and Venezuela. The larger, and much more well-known species, Hydrochoerus hydrochaeris, is found in every country in South America except Chile. In these other South American countries, Hydrochoerus hydrochaeris is only found to the east of the Andes, from Venezuela in the North to the mouth of the River Plate, in Argentina. The Lesser capybara is found in Panama and this is the only country in Central America where capybaras live. Both species of capybara can be found in Colombia but the habitats in which they live are separated by the Andes; the Lesser capybara lives west of the Andes and the larger Hydrochoerus hydrochaeris lives east of the Andes. The Lesser capybara is found in northern parts of Colombia, along the Caribbean coast, the lowland headwaters of several rivers including the Catatumbo river, and the rivers to the north and west of the Sierra Nevada De Santa Marta. The Lesser capybara is also found in some valleys and in the Department of Choco. In Colombia the species is known as ponche or caco culopando, lancha and piropiro among other names. Populations of capybara in Colombia are thought to be small but there is little information available. Venezuela is the only other country where both species of capybara are found. In Venezuela, the Lesser capybara is only found around Lago de Maracaibo in Zulia state, west of the Andes. In Venezuela, as in Colombia, the 2 species of capybara are separated from each other by the Andes mountains. The 2 species are not sympatric, meaning they do not live in the same or in overlapping geographical areas.

Both species live in the same type of habitat: a wide variety of lowland habitats with access to ponds, lakes, rivers, swamps, streams or reservoirs. These habitats include gallery forests, seasonally flooded savannas and wetlands. The highest elevation where capybaras, only the larger Hydrochoerus hydrochaeris, have been found is 1500 meters in the Chapada dos Veadeiros National Park in Goias State in Brazil.

(A gallery forest is where the forested area forms a thin ribbon of trees, only a few meters wide, along a riverbank or bounding a wetland area. The surrounding area, moving away from the river or wetlands, is primarily grassland with at most a sparse scattering of trees. These gallery forests are able to exist because they draw water from the rivers. The extent of gallery forest are diminishing as a result of human activities.)

Like their larger relations, the Lesser capybara, Hydrochoerus isthmius, is semiaquatic and usually most active during the afternoon and at night to avoid predators. Capybaras have subcutaneous sweat glands which are sparsely distributed throughout the body, meaning that their ability to sweat is not well developed, so in order to control their body temperature (thermoregulate) in the heat of the day, capybaras rest in water or under the shade of trees and bushes. Capybaras also use water to escape from predators, and they prefer to mate in water. Water is also the source of their preferred aquatic plants, an important part of the capybara diet.

Capybaras tend to rest in the morning and then escape the heat of the day, in the early afternoon, by resting in water. The herd then grazes, on and off, from late afternoon until dawn. The capybara is a highly gregarious and social animal, most often found in family groups. These groups may be as small as a male capybara and one or 2 females, or larger groups of related females and a dominant male. There may also be 1 or 2 subordinate males, who are tolerated by the dominant male, because they stay on the periphery of the herd and act as lookout. Subordinate males emit the highest number of warning calls to alert the herd to possible danger. These subordinate males do mate, and the aggregate number of their matings may exceed that of the dominant male, but overall the dominant male mates the most. Female capybaras often prefer to be mated by the dominant male, so if a subordinate male is mating with her, she will often cry out, to alert the dominant male as to what is happening, so that he can come over and drive the subordinate male away. Female capybaras will also spent more time running away from, and alluding, a subordinate male who is trying to mate with them, than when a dominant male is chasing them to mate.

Capybaras are a sedentary species whose home range may extend from 5 – 16 hectares, depending on the amount of grazing available. This home range will include a large area of grassland, as grasses (and aquatic grasses) form the major part of the capybara diet, an area of slightly elevated dry land for resting, and a permanent body of water. Capybaras also live in forested/jungle habitats beside a river. In these forested habitats the family group usually consists of one male and 1 or 2 females. The Lesser capybara also eats algae.

There have been no studies indicating that interbreeding between the 2 species of capybara has taken place. However, in Colombia some capybaras of the larger species, Hydrochoerus hydrochaeris, were taken from the Orinoco River region to recreational houses in the Cauca Valley, from where they escaped into rivers and wetland areas.

Encounters between 2 species of the same genus can lead to hybridisation which may have detrimental effects on hybrid descendants. If these encounters are extensive it may result in the local extinction of both parental species. There is no evidence that this has or could happen to these 2 species of capybara, Hydrochoerus hydrochaeris and Hydrochoerus isthmius.

Scientific classification:

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Rodentia

Family Caviidae

Genus Hydrochoerus

Species Hydrochoerus isthmius