For more than a fortnight Dusabimana John was forced to live in a stinking camp for people displaced by fighting in the latest flare-up in the Democratic Republic of Congo.

Like hundreds of thousands of others, he sheltered from tropical rainstorms under plastic sheeting and ate food distributed by aid agencies.

Unlike the others, the ranger from Virunga National Park was as concerned about the animals he had left behind as the humans around him.

“I was worried about the gorillas and elephants,” he said, standing amid ammunition discarded by rebels at the park headquarters in Rumangabo. “That's why I came back. I found myself thinking about them every day. In the war gorillas have been killed. If we are not here then no one can stop them being killed.”

Rangers like him are the only thing keeping the war from destroying Africa's oldest national park. Virunga is one of the last homes of the endangered mountain gorillas. Almost a third of the 700 remaining in the world live in the forest. Others live in national parks in Rwanda and Uganda. Chimpanzees and lowland gorillas, as well as 2,000 varieties of plants and more than 700 bird species, can be found among the volcanic hills that are often shrouded in mist.

The forest affords little protection from the fighting. One sector is the hideout of Hutu militias who fled Rwanda at the end of the 1994 genocide against mainly Tutsis and moderate Hutus. Another sector — where the gorillas live — has been under the control of rival Tutsi rebels for the past year. A month ago the rebels, commanded by General Laurent Nkunda, seized the park headquarters.

There has been fresh wave of violence this week, turning the tranquil forest into a war zone. Further north in the park, General Nkunda's rebels seized government positions and ranger stations. About 240 rangers have been forced to leave.

At the end of a terrible week came a glimmer of hope. Rebels allowed rangers back into the gorilla sector for the first time in more than a year. Emmanual de Merode, the director of the park, drove for four hours into the heart of rebel-held territory on Tuesday to negotiate their return. “It was just a question of explaining that it's a world heritage site of global significance and the park authority has got to continue its work,” he said, playing down any risk to his own safety.

“It's a huge breakthrough for us because we haven't been able to get into the gorilla sector since August last year.” The first rangers found a shell of a building where their headquarters had been. Rebels had carted off most of the furniture and left three mortar rounds amid a jumble of park papers scattered on the floor.

Today the first rangers were due to begin tracking the apes as the first step of a census. An estimated 200 live in the park but no one knows what toll the war has taken. Hundreds of hippos were killed in an orgy of slaughter two years ago, as Government-allied Mai Mai militia went hunting for meat and ivory.

“It's the presence of all these armed groups, the chaos and people who simply need to make a living, that's destroying the park along with a future for tourism and conservation here,” said Mr de Merode.

The region's abundant seams of minerals, and its charcoal forests, provide rich incentive for a dozen or so more militias to keep conflict simmering and the local population in squalid camps.

The rangers themselves have taken a heavy toll. About 120 have been killed since the region was plunged into civil war more than a decade ago.

Now they are returning to continue their crucial work once again. “When the fighting came here we knew we had to leave to protect our families and go to safety in Goma,” said Karonkano Baseka, a returning ranger, speaking in Swahili.

“We cannot leave this place unprotected because there is danger all around and without us there will be no forest. If there is no forest there can be no gorillas,” Karonkano Baseka, a park ranger, said.

As the little furball - all grasping fingers and curious brown eyes - gambols around the lawn there are few signs of Mapima’s miserable start to life.

In places her thick coating of hair has been rubbed bare by the ropes that once bound her. The six-month-old chimpanzee’s head is marked by a sore.

But since being rescued from an army commander by Congolese conservationists Mapima has one thing on her mind: playing rough and tumble with her new carers.

“She loves playing with flowers and eating them,” said Faustin Muhindo Kighomo. She always likes attention and if you ignore her she’ll hassle you until you give in.”

Mapima was spotted tied up at an army roadblock outside the regional capital Goma.

Close by soldiers patrol with monkeys on their shoulders.

While baby chimps are viewed as playthings or valuable commodities, monkeys are believed to ward off evil spirits making them useful companions in war.

Mapima’s ordeal ended 10 days ago when park rangers rescued her from her army captor.

Samantha Newport, spokeswoman for the Virunga park authority, said the latest round of fighting had accelerated the illegal trade in wildlife.

Three baby chimps have been rescued in recent months. But, “most of them slip through the net,” said Ms Newport. “When you have a war and a park that’s badly resourced it’s impossible to protect everything.”

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