It has become a hot destination for backpackers touring South America. The reserve draws an international mix of Americans, Europeans, Israelis and Australians. Adventurous travelers volunteer as caregivers and companions for some of the most exotic and savage beasts on Earth.
These are animals most of us see only in a zoo and only from a distance. But here, those who dare to can hold, pat and play with wild animals they are caring for. It's not quite a petting zoo: Volunteers here work hard in tough, isolated jungle conditions with no luxuries. But adventurers are drawn to the price -- $9 a day for room and board -- and the training requirements: there are none.
All of which makes Caroline Dougherty of Greenwich, Conn., a perfect candidate. At age 18, she has just graduated from high school and is traveling through South America on her own. For the last two weeks, Dougherty has been here at Ambue Ari, feeding and walking an ocelot -- an animal that looks like a small jaguar -- that they call "Lazy Cat."
As Lazy Cat purred loudly at her feet, Dougherty said she had no jungle experience, no training with animals, "but I've always loved animals my whole life."
Spending her days caring for a magnificent jungle cat is a dream for Dougherty -- even if the work is hard and the days are very hot and very humid.
"They get better care than us sometimes," Dougherty joked. "Every morning when we are chopping up fruit for the birds, I want to grab some papaya and some fresh oranges and eat it. But my ration is two pieces of bread, so that's all I get for breakfast."
Volunteers have to commit to work at least two weeks on the reserve, which made Colleen Smith a seasoned veteran. After six weeks at Ambue Ari, she was in charge of the 65 volunteers.
Originally from St. Louis, Smith, 25, who recently graduated from the University of Colorado in Boulder, said it's the exotic animals and the communal atmosphere that bring adventurers to volunteer.
"Obviously, the opportunity to work with animals is a huge draw," she said. "It's pretty unique in the world that you can show up and say you don't have much experience with animals or anything like that and be given the opportunity to work with cats and birds and monkeys."
The hazard and risks of working with animals in a wild jungle is causing more than a little anxiety for Smith's family back in St. Louis.
"I think they think I'm a little crazy and are ready for me to come home," she said. "I have to say that they weren't too happy that I was traveling in the first place," she said. "And when I told them I was staying here, they were less happy."
But Smith's parents can take comfort in the fact that at least she's not taking care of Rupi -- one of five jaguars on the reserve. Rupi gets daily walks in the jungle wearing a collar attached to a rope with three volunteers in tow.
One of Rupi's walkers is Jordan Egger, a slim 19-year-old. He's been at the reserve a month. As he walked down narrow, muddy jungle paths the jaguar -- and all that follow -- had to navigate fallen trees and swampy water that can be several feet deep.
Suddenly, Rupi started running.
"I call it the 110-meter hurdles because it's got so many logs -- and he'll sprint at full pace down and you'll be jumping," said Egger, as he strained to keep up with a 230-pound jaguar that was much bigger than he is.
Egger knew who was in charge.
"Rupi does what he wants," he said.
He also knew that being able hold and touch such an exotic animal in the jungle was something very few people will ever do.
"It's amazing," he said. "I can't wait to talk about it at home. I don't think anybody will believe me.
The animals at Ambue Ari were orphaned, abandoned or seized as illegal pets. None can be returned to the wild, so they live in cages. But the idea behind Ambue Ari is to give them as much freedom as humanly possible. The big cats like Rupi get taken on walks four or five hours a day.
"You get over the fear in about 10 minutes when you realize he is such a sweet cat," Egger said as Rupi rubbed benignly against his handlers. "As long as you treat him with respect and never forget that he is, in essence, a wild animal and you never tug the rope -- he's the boss -- then you'll never come to any harm with him."
But if something did go wrong, Egger and the other handlers would have a very long run through a very muddy jungle to get help. And once they got back to the compound, there's not much help to be had.
The reserve is so remote and primitive that it has no phone service, no car. It is five miles to the nearest phone and almost an hour to a very modest hospital. The full-time staff includes two veterinarians, but no nurse or doctor.
ABC News saw volunteers with injuries and heard stories of bites and gashes, but no one wanted to talk about them.
Each morning, the volunteers and staff assemble outside the dining shack for morning announcements and a group chant.
Overseeing one morning's meeting was Juan Carlos Antezana, the charismatic founder of Inti Wari Yassi, a nonprofit organization that runs Ambue Ari. Speaking in Spanish, he praised the volunteers for their commitment.
"My dream is to one day be able to stop the destruction of the forest, the destruction of the wildlife," Antezana, a passionate environmentalist, told ABC News.
Antezana oversees five reserves with 2,000 animals, including a few dozen big cats, tropical birds and more than 1,000 monkeys.
He said his organization has an annual budget of $1 million. That is a staggering amount in Bolivia, the poorest country in South America, where most people live on just a few dollars a day.
Despite the huge sums Inti Wari Yassi collects, it would be generous to call the facilities for volunteers scruffy.
Antezana insisted there's no reason to worry.
"Thank God, we've never had an accident -- apart from maybe a scratch," he said. "I think it's about love. When people give the animals love, it is difficult for them to attack."'
That's not the way others see it. David Kopp, a biologist with Bolivia's Ministry of the Environment in La Paz, has been asked to look into the operations of Inti Wari Yassi's reserves. What he's seen concerns him.
"To take a jaguar for a walk? It is very dangerous. It can get you killed," Kopp said.
But shutting down the reserve is not an option.
"Where do we take the animals?" Kopp asked. "At this point, there is no other place in Bolivia that can take care of them. ... The solution is not to close it down. The solution is to demand they improve their methods."
Kopp is working to develop regulations that would force the reserve to provide on-site medical staff, emergency phones and more thorough training for volunteers.
Kopp worries that one day the phone will ring with news that someone has been killed at Ambue Ari.
Antezana was incensed upon being told that.
"It is stupid for him to worry," Antezana said. "I think he's making the government look bad. If people are risking their lives here, giving their lives, it is because they believe they are doing something important."
It is exciting to see these magnificent jungle animals up close, and easy to see why it feels worthwhile. Sometimes life can be too thrilling to worry about the consequences.
Take Gilad Goren, 24, a backpacker from New York City with no animal experience.
"You learn more or less to think like the cat -- what he sees ... see how he moves," he said. "You just see how he reacts and you react to it."
After three days of experience, Goren said he understood the law of the jungle.
"The more I am here, I learn humans are animals and these animals are like humans," he said. "If you don't mess with their food, if you show them love, they'll show you respect."
It's an unforgettable adventure -- as long as the animals understand that, too.