A baby gorilla claps her palms and leaps to the top of a wooden climbing frame. Another grips the hands of her keeper and swings head over heels with childlike exuberance. The pair play in long grass in the shade of bamboo, fig and wild banana trees.

This is Ndeze and Ndakasi, symbols of hope in the struggle to save the imperilled mountain gorillas of eastern Africa.

The pair, orphaned in massacres that shocked the world in 2007, are settling into a new home and could soon be part of a new family.

Negotiations are under way to bring two adult gorillas from Rwanda to become their adoptive parents, with a view to returning the babies to the wild.

Innocent Mburanumwe, a warden at Virunga National Park in the Democratic Republic of Congo, said: "An adult male and female were sent to Rwanda during the instability here. We could bring them back and drop them all in a big area to form a family."

The return of the gorillas from Rwanda depends on the completion of the Senkwekwe Centre, a specially designed sanctuary for Ndeze and Ndakasi in a lush forest habitat in Virunga park. The pair, each two and a half years old, moved there last December from a makeshift shelter in the city of Goma.

The babies lost their parents in a spate of killings that cost the lives of 10 gorillas in 2007. Ndeze was found, at two months old, clinging to her slaughtered mother's breast. Photographs of her dead father, a majestic silverback called Senkwekwe, being carried on a bamboo trellis caused international revulsion.

The fragility of life in Congo's eastern forests was brutally underlined last month when two-year-old Nsekanabo, a nephew of Ndeze, died after being caught in a snare laid by poachers. The head of local conservation efforts described the loss as "a catastrophic setback".

The Guardian joined Mburanumwe to watch the baby gorillas at play in their 40x40m walled enclosure from a newly completed viewing platform. "They were found as little babies and taken to Goma," Mburanumwe said. "We put them in a sanctuary there. Doctors gave them milk and medicines.

"But in Goma there is much noise and dust, and the air is not good. The place was not as safe as here. In Goma there was no food, but here we have people collecting leaves and bringing them daily, so it's easy for them to grow. The babies are very happy now and playing every day. It's like the habitat where they were born."

The infants sleep in the same room as their carers at the centre, which was built with support from donors including the Murry Foundation in Britain. It is situated down a forest track next to the park headquarters in Rumangabo, north of Goma.

Mountain gorillas highlight the threat to great apes caused by disease, habitat loss, poaching and war.

A recent report showed that, of the world's 634 primate species, 48% are classified as threatened with extinction on the International Union for the Conservation of Nature's "red list".

The mountain gorilla is critically endangered. There are 720 left in the wild in Congo, Rwanda and Uganda, but this represents an increase from 650 five years ago. "The gorillas are doing much better now than 14 months ago," said Samantha Newport, spokeswoman for Virunga park, adding that rangers had regained control of the gorilla sector from armed rebels in 2008.

Last year the park began offering gorilla tracking to foreign holidaymakers, attracting about 100 a month from countries including Australia, America, Brazil, Britain, Italy, South Africa and Spain. Visitors pay to walk through the forests with a professional tracker and observe the primates in their natural habitat.

Local activists hope that a period of relative political and military stability in eastern Congo could turn it into an unlikely tourist destination, rivalling the more established tracking tours in neighbouring Rwanda and Uganda.

Henry Cirhuza, DRC programme manager of the Gorilla Organisation, a UK charity, said: "It's easier to track gorillas here in the DRC. In Rwanda and Uganda you need to book six months before, whereas here you can book today and go tomorrow. It costs $400 here instead of $500 there.

"You can spend one hour tracking here, whereas in Uganda it can take all day. And tourism is the best way to bring money to the population here."

But while there are tentative signs of declining violence in Africa's oldest national park, grave challenges remain. Poachers still roam here. Several armed groups still live, cook and train in the park. As the death of Nsekanabo last month demonstrated, gorillas still lose their hands, or their lives, in snares intended to catch other animals.

The latest and biggest danger to the gorillas comes from deforestation caused by the relentless demand for charcoal, on which local people are highly dependent for fuel to boil water and cook food.

Cirhuza said: "All the people in this town use charcoal and it's a big threat to the gorillas because of loss of habitat. The gorillas are on a high plane in the mountains. In one or two years they will be reached by those who take charcoal. This park was created for the gorillas in 1925. If we lose the gorillas, there is no park."

Park officials are attempting to combat the trade by distributing kits to local communities to manufacture biomass briquettes from plant waste as a cheaper alternative to charcoal.

Last year it promoted the scheme in an extraordinary publicity stunt, driving around Goma with six people wearing gorilla costumes imported from Britain.

Newport said: "Charcoal is the number-one threat to the survival of the park. It's very difficult to fight because we've living in one of the most densely populated and impoverished parts of Africa. Law enforcement is not enough; you have to provide alternatives such as the briquette programme."