Mountain Gorilla Populations Grow as Conservation Succeeds

Bwindi gorilla
One of the 400 mountain gorillas in Uganda's Bwindi Impenetrable National Park (Photo by Tore Grebberg)


KAMPALA, Uganda, November 27, 2012 (ENS) – The world’s population of critically endangered mountain gorillas has risen to a total of 880 – up from the estimate of 786 animals in 2010. The new population numbers were released by the Uganda Wildlife Authority following a census of gorillas.

Mountain gorillas live in only two places. One location is the Bwindi Impenetrable National Park, which is entirely in Uganda.

Bwindi gorilla
One of the 400 mountain gorillas in Uganda’s Bwindi Impenetrable National Park (Photo by Tore Grebberg)

The other location is the Virunga massif, which encompasses three national parks in three countries – Mgahinga Gorilla National Park in Uganda, Volcanoes National Park in Rwanda, and Virunga National Park in the Democratic Republic of Congo.

Maria Mutagamba, Uganda’s minister of tourism, wildlife and antiquities, announced earlier this month that after a census taken in Bwindi in 2011, the population of mountain gorillas there is now at a mimimum of 400 animals.

“A total of 400 mountain gorillas have been confirmed to be living in Bwindi and 480 were counted in the Virunga Massif in 2010,” said Mutagamba. “Both populations have had positive trends in population growth over the last decade.”

The 400 animals confirmed in Bwindi is up from 302 gorillas counted in the last census there in 2006.

The census results showed that currently there are 36 gorilla families in Bwindi and 16 solitary males. Of the 36 families, 10 are habituated for tourism and research.

The Dian Fossey Gorilla Fund, named after the American zoologist who lived in Virunga for years, provided three experienced trackers from its Karisoke Research Center to assist with the Bwindi census. The Fossey Fund operates daily gorilla monitoring and anti-poaching patrols in Rwanda.

“We are very happy to hear about the increase in the Bwindi population of mountain gorillas and proud of our staff’s contribution to the census,” said Karisoke Director Felix Ndagijimana.

“It’s very encouraging to hear that the conservation efforts both in the Virungas and in Bwindi have been so successful thus far, and we would like to congratulate our Ugandan partners and colleagues in gorilla conservation on the fantastic results of this census,” Ndagijimana said.

Bwindi census team
Researchers track gorillas in Uganda’s Bwindi Impenetrable National Park, 2011. (Photo by Anna Behm Masozera / WWF)

In the Bwindi census, gorilla night nests and feces were documented to generate a current estimate of the population and fecal samples were collected. Teams did two sweeps, one in September and one in November 2011, followed by genetic analysis of the fecal samples. By measuring samples of dung found in the gorillas’ nests, the team could identify how many individuals were in the group and their ages.

John Ndayambaje, the Fossey Fund’s field data coordinator at the Karisoke Research Center, who helped with the Bwindi census, describes Bwindi as being a difficult and dangerous place to track gorillas.

“It was very, very difficult for the trackers to cut and make a way for the others with notebooks, GPS, compasses, and all the other equipment,” says Ndayambaje.

The trackers had to clear trails through the dense vegetation, and the many swamps, hills, ravines, and rivers posed risks for trackers who had to follow a very specific set of GPS coordinates as they conducted the census.

Rain turned the ground to mud, making life difficult for the trackers. One night, says Ndayambaje, heavy rains destroyed his team’s entire camp, and they had to replace much of their food and equipment.

The unhabituated gorillas were difficult to count accurately, says Ndayambaje.

“It was not easy, when we found a group which was not habituated, to know how many were in the group. We had to track back to see how the nests were and try to count the nests and collect samples,” Ndayambaje says.

The census is key to understanding whether conservation work is succeeding, and involved government agencies in the three countries as well as a dozen environmental groups and academic institutes.

“Mountain gorillas are the only great ape experiencing a population increase. This is largely due to intensive conservation efforts and successful community engagement,” said David Greer, African Great Ape Programme manager with the global conservation group WWF, whose Swedish branch helped to fund the census.

The greatest threats to mountain gorilla survival are entanglement in hunting snares, disease transfer from humans, and habitat loss.

Bwindi forest
View overlooking Bwindi Impenetrable National Park (Photo by The Far Horizons)

The possibility of oil exploration in Democratic Republic of the Congo’s Virunga National Park is also cause for concern, says Greer.

While oil drilling would not occur in gorilla habitat, industrial activity would compromise the integrity of Virunga National Park, Africa’s first national park and a UNESCO World Heritage Site, warns Greer. An influx of workers and heavy equipment could threaten all of the park’s wildlife, including elephants, hippos and rare okapi antelopes.

“More people in Virunga would likely lead to an increase in deforestation, illegal hunting and more snares in the forest,” Greer says. “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.”

Gorilla conservation is critically important says Ndagijimana of the Fossey Fund’s Karisoke Research Center.

“Besides the fact that Bwindi Impenetrable Forest and the Virunga Volcanoes are the only forests on Earth where we can find mountain gorillas,” Ndagijimana said, “the differences in these two separate populations provide important clues to the evolutionary history of these great apes and to the species’ adaptations to different types of forest habitats.”

The 2011 Bwindi mountain gorilla census was conducted by the Uganda Wildlife Authority with support from l’Institut Congolais pour la Conservation de la Nature and the Rwanda Development Board.

The census was supported by the International Gorilla Conservation Programme, a coalition of the African Wildlife Foundation, Fauna & Flora International, and WWF, as well as the Max Planck Institute for Evolutionary Anthropology, Conservation Through Public Health, the Mountain Gorilla Veterinary Project, the Institute for Tropical Forest Conservation, and the Dian Fossey Gorilla Fund International.

This census was funded by WWF-Sweden with supplemental support from Berggorilla & Regenwald Direkthilfe e.V., the Wildlife Conservation Society, and the Max Planck Institute for Evolutionary Anthropology.

Copyright Environment News Service (ENS) 2012. All rights reserved.

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