Inside daring helicopter mission to save largest species from extinction
Poaching, habitat loss and war have slashed the eastern lowland gorilla population in the Democratic Republic of Congo, so conservationists are taking drastic measures.
The forest presses in from all sides, vines snagging at the ankles. A tight weave of poles and creepers shuts out the sky and obscures the source of birdsong overhead.
Trackers, carving our path with machetes, stop abruptly and signal.
Ahead, the undergrowth shifts with a crack of bamboo to reveal a vast, dark figure slumped in the tangle. The eyes fixed on us belong to one of the few eastern lowland gorillas left in this pocket of Congo.
Our ranger emits a low, rumbling grunt. “I am telling him we know this is his place and we come as friends,” Benoit Ishaba says of the silverback in a remote spur of the Virunga National Park in the eastern Democratic Republic of Congo.
A juvenile male peers shyly down from a thicket, thumps his chest in a show of bravado and scampers off.
Isolated and under threat
Grauer’s gorilla (Gorilla beringei graueri), the world’s largest primate, is found only in this region, where decades of poaching, habitat loss and conflict have left them critically endangered.
Eastern Congo is rich in natural treasures, but for decades it has been beset by violence, particularly over the minerals that power the global tech economy. Even Virunga, Africa’s oldest park, has been drawn into the fighting: Rwanda-backed M23 rebels occupy its southern and central sectors, forcing its closure to tourists.
Yet on Mt Tshiaberimu, against this backdrop of instability, conservationists have pulled off one of the boldest interventions ever attempted with one of humanity’s closest relatives.
Since the mid-1990s, when Rwandan forces spilled over Congo’s eastern border hunting genocide perpetrators, the chaos has slashed the populations of the two subspecies found in this region – the mountain gorilla and the eastern lowland (or Grauer’s) gorilla.
There were an estimated 16,900 Grauer’s before the unrest, but the most recent count put the population at 6800, occupying a fraction of their historical forest range.
On Mt Tshiaberimu only eight Grauer’s gorillas were left in 2024, split between two groups led by the silverbacks Katsabara and Mwasa.
The group, which is the most genetically isolated from other remaining populations further south, was deemed on track for functional extinction, so drastic measures were judged worth the risk.
The rescue
In October last year, four adult female Grauer’s gorillas, rescued as orphaned infants and raised at the Grace sanctuary near Virunga, were flown one by one by helicopter to Mt Tshiaberimu.
The goal was ambitious: to see if they would eventually join and revitalise the wild groups. It was the largest translocation of the species ever attempted and had been five years in the planning. Twenty experts modelled and mitigated every eventuality.
A scaled-down version of the sanctuary – with fenced enclosures, an overnight shelter and a lab for a specialist vet – was built on the mountain to allow for the most comfortable acclimatisation to its higher altitude, colder temperatures and unfamiliar diet. Isangi, Lulingu, Mapendo and Ndjingala had all seen their families killed and were brought to be cared for at Grace, the only sanctuary dedicated to Grauer’s gorillas, which are slightly larger than the better-known mountain gorillas.
Ndjingala was found tied with rope and being offered for sale to the exotic pet market, and Isangi, then nine months old, was discovered in a remote village after poachers butchered her group.
At Grace they were brought up by human carers where, alongside other rescued gorillas, they learned to forage, climb, build nests and socialise.
Now sexually mature, skilled and good friends, the four – aged between 10 and 16 – were identified as the best candidates to move into the wild population at Mt Tshiaberimu, which means “the mountain of the spirits”. Local communities traditionally believed the great apes on its slopes were the reincarnation of their ancestors.
Dalmas Kakule Syangeha, 35, the animal care manager who helped to raise the four gorillas at Grace, relocated with them to Mount Tshiaberimu.
Additional caregivers were trained and stationed alongside Virunga rangers who protect the park.
“We thought it would take months, even years for them to become wild,” Syangeha said, “but their natural instincts took over.”
They stayed for five weeks at their enclosure, browsing new vegetation and responding to gorilla exchanges from the distant forest, but sleeping inside until late November, when a 200kg silverback named Mwasa arrived at the fence and stayed. He proved his interest with loud rumbling calls, beating the ground and sleeping in sight.
The females’ response was blunter still. They spurned their shelter to make nests outside, their first night in the open, and showed aggression to their human carers. In a striking show of intentional tool use, one broke off a bamboo pole and used it in an attempt to scale the fence.
The release
It was becoming unsafe to keep the increasingly restless females enclosed as they vocalised and tested the perimeter, and Syangeha and his colleagues had little choice but to let them go.
Katie Fawcett, the director of Grace, said: “In the end the release was fast and dramatic – with the carers on the ground leading the decision. We had talked through every scenario about what that moment looked like. In the end, it was the gorillas who chose it.”
The four went without hesitation to Mwasa, who accepted them in typical silverback fashion, with a few assertive slaps. The carers’ attempt to follow at a distance were rebuffed by the females, who charged.
Ishaba, the ranger who monitors Mt Tshiaberimu’s gorillas, advised the Grace carers to stay away to allow the females to be accepted by Mwasa’s original female and their infant. Reports of their thick coats and rounded bellies, along with saliva and faecal tests from their nests, indicate they are thriving – healthier than in captivity, Ishaba said.
The original female in Mwasa’s group has accepted the newcomers and trusts them with her infant. There is hope that more births might follow this year or next.
Emmanuel de Merode, head of the park, said: “That would be the very first successful reintroduction of captive gorillas into a wild population that leads to offspring. If this population comes back to life as a wild population then that’s a very big moment for Virunga.”
A new life
Despite years of forest loss and fighting over Congo’s spoils, the Grauer’s better-known mountain gorilla cousins in the Virunga Massif – which spans eastern DR Congo and neighbouring Rwanda and Uganda – have shown signs of recovery. Their numbers rose from 480 in 2010 to more than 600 by 2016, contributing to a total today of more than 1100.
The improvement is credited largely to ranger patrols and sustained conservation efforts.
Initiatives supporting local livelihoods – such as eco-tourism and farming – have eased some of the pressure on the forest. But armed groups remain active in the region, and the habitats of all the park’s wildlife continue to face serious threats.
At Grace, more potential candidates are being identified for another translocation, if and when the first four are considered settled and have had young.
It is a remarkable but wrenching process, Syangeha admitted.
“It did break my heart that they left so quickly and firmly,” he said. “But they have gone to the life that they should have always had. That means we have done our job.”
The Times
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