A Ugandan survey found that the population has risen from 786 in 2010 to 880 today, due to conservation efforts

The world's population of mountain gorillas has increased by more than 10% in two years, new census figures show.

A survey carried out in Uganda's Bwindi Impenetrable national park and released by the Ugandan Wildlife Authority has found that numbers of the critically endangered species, Gorilla beringei beringei, have risen from an estimated 786 in 2010 to 880 today.

Threats to the mountain gorilla – including war, habitat destruction and disease – were once thought to be so severe that the species could become extinct by the end of the 20th century, but the population has increased significantly in the last 30 years.

Drew McVey, species programme manager at WWF-UK, who supported the census as part of the International Gorilla Conservation Programme, said he believed the latest increase was due to conservation efforts that had successfully engaged the local community.

"Mountain gorillas have only survived because of conservation. Protected areas are better managed and resourced than they have ever been, and our work is a lot more cross-cutting to address threats - we don't just work with the animals in the national parks, but also with the people."

McVey said conservation now balanced species survival against the needs of an incredibly poor area with high population pressures, for example, tackling the loss of gorilla habitat due to the illegal collection of firewood by providing the community with access to alternative energy sources.

Mountain gorillas, a subspecies of the eastern lowland gorilla, live in mountain forests in only two locations in the world – Bwindi in south-west Uganda and the Virunga Massif, a range of extinct volcanoes that border the Democratic Republic of the Congo, Uganda and Rwanda.

According to the census report, there are more than 400 mountain gorillas in Bwindi, living in 36 distinct social groups, with 16 solitary males. Ten of these social groups are accustomed to human presence for either tourism or research. A 2010 survey counted 480 individuals in Virunga Massif.

"Gorillas are slow breeders," McVey said. "And we're quite impressed with how much the population has increased."

But McVey said this should not be read as a sign that the fight to save the species is over. "Mountain gorillas are only found in protected areas, and outside these areas there are more than 600 people per square kilometre, so there is immense pressure to secure their habitat and pay their way. We haven't got everything right yet, but it's vital we continue to keep working and build on this success."

The number of mountain gorillas has increased from the 2010 estimate of 786 after a count in Uganda’s Bwindi Impenetrable national park. Photograph: Anna Behm Masozera/WWF

The greatest current threats to mountain gorillas are entanglement in hunting snares, disease transfer from humans, and habitat loss for agriculture and livestock.

"Gorillas have almost the same DNA as us, and humans can transmit anything from a common cold to ebola. Gorilla populations are incredibly fragile and sensitive to environmental change. There are only two populations, so disease could easily wipe out an entire population," said McVey.

The prospect of oil exploration in Democratic Republic of the Congo's Virunga national park by petroleum companies has also become a cause for concern.

"More people in Virunga would likely lead to an increase in deforestation, illegal hunting and more snares in the forest," said David Greer, WWF's African great ape programme manager. "At least seven Virunga mountain gorillas have been caught in snares this year and two did not survive. The gorilla population remains fragile and could easily slip into decline if conservation management was to be disregarded in the pursuit of oil money by elites."

The number of mountain gorillas declined dramatically during the 1960s, stabilised during the 1970s and started to increase in the 1980s. Political instability and war prevented a complete census until 1989, when it was revealed that there were 620 individuals.

The war in Rwanda in the early 1990s and years of civil unrest in the DRC led to poaching and destruction of gorilla habitat and made survey and conservation work difficult and dangerous. Since 1996, 140 Virunga rangers have been killed in the line of duty, including one in May.

Many mountain gorillas have become accustomed to human presence and are a major tourist draw. In 2009 Virunga national park – home to the largest mountain gorilla population – received 550 visitors. This year visitors were projected to reach 6,000.

"The amount of revenue and jobs that gorillas generate is so important for these areas that are so desperately poor," McVey said. "People really see gorillas as important for the national and local economies, and a portion of this goes back to conservation efforts and the local community."

But park authorities have been forced to suspend tourism again after fighting, and last month a Congolese rebel group accused of killings, mass rapes and other atrocities was found to be using the proceeds of gorilla treks to fund its insurgency.