New documentary follows pair as Mr Gruener teaches Sirga to hunt

Dozing in a mother's lap, eyes half-closed, or throwing their arms around a father's shoulders in a great hug — every child craves a parent's affection. For Sirga the lioness, it is no different.

Though, in this case, her parent is a human.

Conservationist Valentin Gruener, 27, co‑founder of the Modisa Wildlife Project in the Kalahari, Botswana, has his hands full with the three-year-old lioness he has raised almost from birth.

Now a teenager in lion years, Sirga is preparing to live in the wild — and surrogate parent Valentin is teaching her to hunt.

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Friends for life: The story of the abandoned lion cub Sirga who was raised by a German wildlife enthusiast in his 20s was one of the most shared stories on social media last year

Sirga was found close to death on a farm, in February 2012, after a litter of three cubs was born to a pride of lions. Two of the babies died and the third was abandoned by the adults.

Working with a vet, Valentin put the tiny animal, weighing just 4lb, on a drip to combat severe dehydration.

Over the next few days, he experimented with a recipe to fatten her up, until he hit upon a mixture of fresh eggs, cream, milk, vitamins, sunflower oil and calcium.

'To this day we believe she is probably the most spoiled and well-fed lion in Botswana,' he laughs.

Within a year, she had put on 175lb, was weaned and was eating raw meat.

Valentin, born in Germany, and his fellow conservationist, Mikkel Legarth from Denmark, were determined to help Sirga return to the wild, and have been coaching her to hunt.

That meant hours spent teaching her to stalk and kill — skills which are not wholly instinctive and which cubs typically learn from the adults in their pride.

'We didn't want Sirga to become like other lions in captivity, constantly fed by streams of tourists,' says Mikkel. 'She hunts her own food, taking antelopes, and she will let us be near her when she eats it, which is remarkable.

'We want to release her eventually as a wild lion, not as one who has met lots of people. That would be dangerous. She only interacts with me and Valentin.'

Best buds: Conservationist Valentin Gruener, 27, raised Sirga after she was abandoned by her pride

New challenge: A documentary series follows Sirga and Mr Gruener as he teaches her how to hunt

Realising that they were developing a unique bond with Sirga, the two naturalists invited filmmaker Jurgen Jozefowicz in, and a six part series called Lionheart will be released later this year.

The film shows how Sirga nuzzles and even hugs her human 'parents', and will allow them to scratch her tummy or rub her jaws.

She keeps her claws sheathed during play sessions and lies with her head contentedly on Valentin's lap while he strokes her ears.

Most of us can only imagine the thrill of raising a lion from a cub.

But John Partridge, senior curator of animals at Bristol Zoo Gardens, and his team have shared a similar experience over the past two years.

As Sirga does not have a pride to teach her how to hunt, Mr Gruener has to get down and dirty and show her

In order to teach her how to live as a wild lion, Mr Gruener has spent many hours crouching in scrubland or pouncing in watering holes alongside Sirga

Success? A proud Sirga managed to catch a large swollen toad, and carried it in her mouth

The zoo's pair of endangered Asiatic lions had twin cubs, called Kamran and Ketan, in November 2012. But the mother rejected them when they were just 13 days old after her mate died.

'We don't carry out hand-rearing unless there's a strong reason,' emphasises John. 'If the babies have been with their mother for a while, it is quite a challenge to get them used to artificial milk and teats, as they are obviously used to suckling naturally.'

Lions reared by humans will treat them as part of their pride, he says.

Many readers will remember the story of John Rendall, who bought a lion cub in the pet department at Harrods in 1969 with his friend Anthony Bourke, and raised it in his flat above a shop on the fashionable King's Road in London.

As one: Mr Gruener is fulfilling a lifelong ambition by living with lions in the wilds of Africa

Family: Mr Gruener observes as a veterinarian cares for his beloved lioness friend

The new documentary has been called an 'extraordinary story that transcends all known borders between man and lion, predator and prey' by its makers

Sustainable living: A team from the Modisa Wildlife Project feed a group of young male lions in an enclosure

When the cub, who they called Christian, outgrew the flat, they arranged, with the help of conservations, to introduce him to the wild in Kenya.

When John and Anthony returned to Kenya a year later, Christian recognised them instantly, putting his paws on their shoulders in rapturous excitement.

The footage subsequently became an internet sensation when it was posted on YouTube in 2008. It has since been watched more than 100 million times.