Flamingo Land's three Sumatran tiger cubs are now more than four months old. STEPHEN LEWIS went to meet them - and their formidable mother.

THERE'S something very unsettling about the smell of tiger. It's musky, potent, primal - and it makes the hair stand up on the back of your neck.

The neck hair stands up even more when Surya, Flamingo Land's adult female Sumatran tiger, stalks noiselessly towards me on huge, cushioned feet.

I'm suddenly very glad that there are thick metal bars between me and her. She gives me an intent stare, the striped face impassive, the tawny eyes fathomless.

"When she looks at you like that, she's definitely deciding which bit of you to eat first," says Surya's Keeper, Christine de Cunha.

Surya made the headlines when, a couple of months ago, her three cubs were first presented to the world. 'Meet the new arrivals at Flamingo Land', went the headline in The Press, above a photograph of a very kittenish-looking tiger cub still clothed in its baby fur.

The cubs were just a couple of months old, then. Now, in late July, they are more than four months old - and they've grown. They're already as big as medium-sized dogs, weighing in at 15-18 kilos each, and are full of beans.

And they are already developing distinctive characters of their own, says Christine.

Kuasa, the boy, is the biggest - and he'll keep getting bigger than his two sisters as the three of them continue to grow. Mentari is the bolder of the two sisters, while Bulan is shyer, and tends to cling to her mum more - though for that reason, she's often easier for visitors to see. "Mentari and Kuasa are really playful," says Christine. "Bulan is a bit quieter."

While I come to meet Surya face to face indoors in the pen behind the tiger enclosure, the three cubs are romping in the sun outside, entertaining an admiring audience.

Lunch has just been served, and the cubs are playing with their share - a dead duck, given to them complete with feathers.

They're play-fighting over it, tossing it, shaking it from the neck, giving an occasional heavy biting crunch of the teeth. It's all innate behaviour, built into them from the moment they were born, says Zoo Manager Ross Snipp. "You can see them practising the skills they would need to survive in the wild, like stalking," adds Christine.

Surya is a great mum, Christine says - protective and caring. The cubs are still suckling - it will be two years before they are fully grown - but they have also started eating meat. It won't be long before Surya starts to discourage them from taking milk, Ross says. "They have a fair set of teeth now!"

For the moment, having taken the cubs their lunch, Surya has retreated into the cool of the pen behind the enclosure to enjoy her own lunch in peace and quiet.

She appears oblivious to our presence as she crunches her own duck, devouring it bones, beak, feathers and all.

In fact, while she's not showing it, she'll be very aware of us, says Ross. "Christine will be a familiar, comforting smell. Surya will probably recognise me, and think that I'm the guy who turns up when something is wrong. If they see me, they often see the vet too!"

And me - well, I'd just be an extra course for lunch, if Surya could get to me.

Even though there are thick bars between us bars, Ross warns me not to go too close. And on no account put my hand through the bars, he says. "Anything you put through the bars, you won't get back."

I don't need telling twice. Because, cute as the cubs romping outside in the sunshine are, these animals are not pets. They're wild at heart - and they are killers.

The Keepers at Flamingo Land have adopted a policy of not attempting to domesticate them in any way. Let tigers be tigers, is their motto.

"This isn't Sumatra," admits Ross. "It is Malton, North Yorkshire. But everything we do is to try to make things as natural as possible for them. That includes minimal contact with the Keepers."

The tiger enclosure belongs to the tigers, in other words. They can be enclosed off in the pen area behind if Keepers need to do any cleaning or maintenance work in the acre or so of open enclosure. But never, under any circumstances, would a Keeper go in there while the tigers are there themselves. "You wouldn't come out again," Ross says.

There are five Sumatran tigers at Flamingo Land - Surya and her three cubs, plus their father, Surya's mate Bawe. He's big and sleek - a hefty 115 kilos compared to Surya's 90 - but he's also very laid back, says Christine. In the wild, it is usually the male tiger which is dominant. But there is no doubt who is boss in Flamingo land's adult breeding pair - and it isn't Bawe. "He's very lazy!" Christine says.

He also has nothing to do with his three offspring: in fact, his half of the enclosure has been separated off from that holding Surya and the cubs. That's how it should be.

In the wild, a male Sumatran tiger would control a big territory in which there would be several females, each with their own territory. "He would patrol from one female territory to the next, checking whether they were receptive. But he wouldn't have seen her (Surya) since the day he got her pregnant," Ross says.

Surya and Bawe do sometimes call to each-other, however - a deep, oddly muted 'mrrow!' that's half-way between a snarl and a miaow - and Bawe is allowed to see Surya every morning, while the cubs are outside.

Apart from keeping Bawe separate, the tigers are given complete freedom to move around their enclosure - going outside when they feel like it, or retreating into the cool and quiet behind when they want to. It was here, in the cool darkness, that Surya chose to give birth.

Despite the Keepers' every attempt to give the tigers their freedom, and to make their surroundings as natural as possible - and despite the tigers' obvious health and well-being - there are still those who feel uneasy at the sight of great wild beasts like these being kept captive.

But the truth is that without breeding programmes such as that at Flamingo Land, they would probably soon be extinct altogether.

Sumatran tigers - like other tiger sub-species - are critically endangered, Ross says. There are thought to be between 300 to 550 Sumatran tigers left in the wild, living in the forests of Sumatra - and 100 living captive in zoos around the world.

The trouble is that in Sumatra, the forests in which they live are rapidly disappearing, due to due to rampant deforestation and conversion into agricultural land. The tigers are also hunted, because their bones are an ingredient in Asian medicine.

These twin pressures make the wild population hugely vulnerable. Ross is often asked if the zoo's three cubs, Kuasa, Mentari and Bulan, might one day be reintroduced to the wild. "But there is very little wild left, that's the crux of the matter," he says.

Flamingo Land zoo is working on a conservation project in Tanzania, trying to protect forest there. Other zoos are doing similar work trying to protect forest in Sumatra, Ross says.

But it will be a long time, if ever, before deforestation can be ended and habitats begin to recover.

Until then the breeding programmes are crucial. "Without zoos, the speed with which they (Sumatran tigers) would end up like the dodo and the dinosaurs would be accelerated," Ross says.

It turns out that man is much more of a killer than these magnificent animals after all.