The number of mountain gorillas living in the Virunga Massif in central Africa has soared by 26.3% since 2003, according to a new census. The increase in numbers from 380 to 480 individuals is thanks to "immense" efforts to reduce poaching and disease, scientists said – but should not be read as a sign that the fight to save the highly endangered species is over.

The 450-square-kilometre Virunga Massif is composed of three national parks: the Volcanoes national park in Rwanda – made famous by the film about the conservationist Dian Fossey, Gorillas in the Mist – the Mgahinga gorilla national park in Uganda and Parc National des Virunga in the Democratic Republic of Congo. According to the census, which was conducted in March and April this year, its gorilla population is growing at a rate of 3.7% a year.

"This is a spectacular upsurge," said Martha Robbins, a primatologist based at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who led the study. "The resources put into their conservation is immense, but it shows that with enough effort it is possible to bring a population back from precariously small numbers."

The mountain gorillas of the Virunga Massif are making a comeback for a variety of reasons, said Robbins. One key driver is the International Gorilla Conservation Programme, which started to engage local communities in projects that would help them to develop economically in 2003. "Many of these communities now keep bees to make honey or make handicrafts for tourists. They don't need to poach."

In addition, fewer gorillas are dying from diseases and injuries. Veterinarians monitor the gorillas for many hours every day, and treat ill individuals or those that have been injured by snares, which are laid out by locals to trap antelope. The presence of the veterinarians not only saves the gorillas from disease but also from poachers, who are less likely to attack when they are there, said Robbins.

According to Eugène Rutagarama, director of the IGCP, the main reason for the rise in gorilla numbers is an increase in patrols and guards in Volcanoes national parkin Rwanda. Equipped with more radios and patrol cars, the guards are getting more and more efficient at thwarting poachers, he said. "In 2002, Rwanda's national parks went through a restructuring process. They got more rangers on better salaries, more radios, more patrol cars and better training in wildlife conservation. They also built more shelters in the park, from which rangers could protect the gorillas." These patrols remove more than 1,500 snares a year.

According to Rutagarama, the governments of Rwanda, Uganda and Congo are currently scrutinising a new treaty that will legally bind them to protect the gorillas and their habitats – and could sign it in the coming week. "They also signed a memorandum of understanding in 2002, but that wasn't binding, so this treaty will make a real difference," he said.

The number of mountain gorillas, Gorilla beringei beringei, 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 250 individuals. Today, there are 780 mountain gorillas in total in the wild, 300 of which live in Bwindi Impenetrable national park in Uganda.

In March and April this year, scientists from the IGCP, the Dian Fossey Gorilla Fund, the Rwanda Development Board and the Uganda Wildlife Authority carried out a new count by following groups of gorillas for three days at a time and genetically analysing their faeces. They found 36 groups of gorilla in the Virunga Massif, along with 14 solitary silverback males.

Luckily, there is no appetite among local communities for gorilla meat, says Rutagarama. "The snares are laid for antelope, but accidentally trap gorillas, however. A more serious problem is that poachers try to trap baby gorillas and sell them to foreign zoos. To our knowledge, not a single one has survived the journey."