Endangered mountain gorillas are making a “slow but steady” comeback in one of their last strongholds, a genetic census has shown.

Population numbers of the species, which memorably allowed Sir David Attenborough to sit among them during filming of the documentary Life on Earth, have been boosted by 12 per cent over the last decade in Uganda.

Their steady resurgence indicates that while the numbers are still small, the gorillas in the Bwindi Impenetrable Forest form a “healthy and well-protected” population.

Mountain gorillas, Gorilla beringei beringei, are one of the most threatened animals in the world, with only 720 left in the wild after years of decline in the face of hunting by humans and habitat loss.

In Bwindi, in southwest Uganda, where they live in a national park, genetic analysis of stools revealed that the population had risen by 40 to 340 in ten years.

Genetic analysis of faecal samples was chosen as the means to calculate animal numbers because it avoided the problems of double-counting.

A further 380 mountain gorillas live in Rwanda and the Democratic Republic of the Congo (DRC), where there has been concern for their welfare because of civil unrest and hunting by humans.

“This is indeed great news for the survival of the mountain gorilla,” said Marc Languy, of the WWF, one of several conservation groups involved in the census. “This is an annual growth rate of about 1 per cent, which is indicative of a healthy and well protected population.”

He cautioned, however, that the survival of the species remained far from guaranteed: “With only about 720 individ-ual mountain gorillas surviving in the wild, more efforts are still needed to ensure that these beautiful animals do not become extinct.”

Nevertheless, the finding has boosted morale among wildlife groups, which earlier this year were alarmed by the discovery of the remains of two adult male gorillas. Both silverbacks had been killed by people and there was “clear evidence” that at least one of them had been slaughtered for the bushmeat trade.

The animals were part of the gorilla population in the Virunga region — a cross-border area shared by Uganda, DRC and Rwanda — where four years ago survey evidence suggested that numbers were recovering after years of decline.

Mountain gorillas leapt into the limelight in 1978 when they were filmed clambering over and around Sir David Attenborough in a scene that became one of the most well-loved of all wildlife film footage.

Those gorillas were from Rwanda, where they had been the subject of years of groundbreaking study by Dian Fossey, whose life was portrayed in the film Gorillas in the Mist.

Eugene Rutagarama, of the International Gorilla Conservation Programme, said: “Joint conservation efforts between Uganda Wildlife Authority, park authorities in Rwanda and the DRC, and conservation organisations can pay off.”

Going ape

— “Keep low and grunt a lot” — Dian Fossey’s advice to Sir David Attenborough and the Life on Earth crew for approaching gorillas

— The gorillas of East and West Africa are different species

— They rest for 40 per cent of the day; at night they build nests of vegetation to sleep on

— Mountain gorillas live at altitudes of 8-13,000 feet. They eat 142 species of plants but only three fruits

— The average male weighs 25 stone but can reach more than 30 stone. Gorillas can live for 50 years

— Silverbacks, the adult males, will beat their chests to warn off any animal they see as a threat. They will also hoot, slap the ground and throw plants

— They communicate where they are by belching

— Infants suckle for three and a half years

Source: Times database

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