Otto Bell was surfing the web at work when he saw the photographs that enticed him to sink his life savings into his first feature film. On his screen was a rosy-cheeked, Mongolian girl. Perched on a mountain ridge, she was smiling with delight at a ferocious golden eagle flapping on her arm.

The scene was a world away from the office cubicle in New York where Bell was sitting. The shots were taken in the Altai mountains which, Bell points out, “is the most remote part of the least-populated country in the world”. The 35-year-old had no financing and had only ever made short, commercially funded documentaries. Yet in a “pretty short time”, he had tracked down the young Israeli photographer Asher Svidensky, convinced an American cameraman to accompany them, and was on a flight to Mongolia to track down the teenager.

The result is a joyful, majestic film – a documentary (narrated by Star Wars’ Daisy Ridley) that feels like a fairytale as it follows 13-year-old Aisholpan’s quest to become a record-breaking eagle hunter. Amongst her nomadic Kazakh community, the tradition of capturing and training young golden eagles to hunt foxes and rabbits is passed down from father to son. And to achieve her dreams, Aisholpan must overcome the scathing elders, who insist that a woman cannot, and should not, hunt.



Sitting in a smart London hotel, with the film hitting $1.2m at the US box office and shortlisted for an Oscar, the 35-year-old can afford to laugh at his recklessness. “Kids, animals, extreme conditions, a foreign language,” he reels off with a laugh, “all the things you are not supposed to work with.”



It wasn’t just the painterly beauty of the photographs that drew him in, but their cinematic qualities: “A beautiful location, a fantastic bird and Aisholpan – even in that photograph she looks angelic, but also really strong.”

The day the trio finally tracked down the nomadic family, Bell was nervous they might be wary of being filmed. Instead her father Nurgaiv made an extraordinary offer. “He said, ‘This afternoon we are going down the mountain to steal an eagle for Aisholpan. Do you want to film that?’”



She made a dizzying descent of a sheer cliff with just a rope around her

Aisholpan had her eye on a fledgling. For days, she had been watching her (female eagles are always used because they are larger) through her father’s old broken binoculars. She was the perfect age to be taken: able to survive without her mother, but young enough to be trained.



Capturing Aisholpan’s dizzying climb down a sheer cliff to an eagle’s nest, with only a rope tied round her waist, posed problems for them all. For a start, the cameraman was afraid of heights so could only film from solid ground below, and the photographer Svidensky wasn’t best-placed to step in as he’d never shot moving images. So Bell had to get creative – strapping a GoPro inside Aisholpan’s cardigan and climbing with Svidensky to a ledge opposite the nest, to capture another angle.



It’s a heart-stopping scene: a young girl with plaits jauntily tied with pink ribbons makes a terrifying descent while an angry mother eagle circles menacingly overhead. So perhaps it’s not surprising that some reviewers have assumed the scene is a re-creation. Bell is obviously frustrated, but tries to take as a compliment. “We did it in 12 minutes in one take,” he says flatly.



Resolve … Aisholpan takes part in the hunters’ festival. Photograph: Allstar/Sony Pictures Classics

Later we see Aisholpan entering the golden eagle festival in Ölgii, a high point in the nomad calendar and a competition her father has won twice. Watching the bird swooping from a mountain in response to the young girl’s call is visually astonishing, but it also shows the huntress’s resolve in the face of older male competitors. “She is strong,” Bell says. “She loves to win – whether it is chequers, wrestling with boys, or hunting with an eagle.”



But much of the pleasure lies in these gentler scenes, which show the love between Aisholpan and her father: the way he adjusts her hat, the pride in his voice when he talks about her, his patient teaching. “I started off thinking this was a female empowerment movie,” Bell says. “While that is still there, it also became a film about a father and his daughter.”



Bell is quick to point out that Aisholpan’s talent and hard work have been as important as her parents’ open-mindedness. “I don’t think her family woke up one morning and were like, ‘We are going to be crusading feminists.’” From the start, Aisholpan had an affinity with her father’s eagle – even as a baby, she would crawl over to it. Aisholpan’s older brother being conscripted into the Mongolian army was a factor, too.



“She took over a lot of his chores – things that were traditionally seen as boys’ jobs. She used this as leverage: ‘If I am doing all these jobs, why can’t you teach me the eagle stuff?’ She’s quite canny.”



Bell was planning to return to Mongolia to film Aisholpan’s first hunt, but he had run out of savings and blown his bank loan. After sleepless nights worrying, he sent some edited footage to Morgan Spurlock, the award-winning maker of Super Size Me. “It was a little cheeky,” he says. “I had never met him in person. Thankfully, he called me back that day and said, ‘I have never seen anything like this. How can I help?’ It was like the clouds parting.”

High-flier … Aisholpan, left, at her school studies; she wants to be a doctor. Photograph: Sony Picture Classics

But all the money in the world couldn’t soften the extreme Mongolian winter. The hunt, which should have taken three days, took 22. In temperatures of -50C, equipment failed, the crew fell into snow flurries and capturing something as unpredictable as an eagle grasping a fox proved elusive. Unsurprisingly, tempers frayed. “We messed up their hunt,” Bell admits. “We could only film for three or four hours a day when the sun was up, and the temperature rose to minus 25. We all got annoyed – except Ashiolpan.” Despite the demands of carrying a 10kg eagle on her arm while galloping through snow, the huntress remained determined – which kept Bell’s spirits up.



He hopes The Eagle Huntress’s success will boost tourism and help the community continue their ancient tradition, which is under threat as nomads move to the city. “A lot of the herders are being hammered by climate change,” says Bell. “Vicious winters are literally freezing whole herds to death overnight.”



Although Aisholpan and her family still live as nomads, there are changes. Bell says they are all coming to his wedding next year. And, as a result of her fame, Aisholpan has been given a scholarship to one of Mongolia’s best schools, while an educational trust set up for her also means she can pursue her other lifelong dream: to become a doctor. It’s an ambition that underlines Bell’s image of Aisholpan: the little girl with a soaring eagle on her arm, but with her feet firmly on the ground.