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New Gorilla Census Begins

Feb. 10, 2010

New Mountain Gorilla Census Starts March 1

Full census of Virunga mountain gorillas also includes health status

A much-anticipated new census of the mountain gorillas will begin March 1 in the rugged Virunga mountains that straddle the border between Rwanda, the Democratic Republic of Congo (DRC) and Uganda. Eighty trackers and team leaders, including 14 Karisoke Research Center staff, as well as staff of the three national park and wildlife authorities and other partners, will systematically walk a network of trails from east to west throughout the gorillas' entire habitat. The count will be based on observations of night nests and dung samples (to determine age and sex of individuals in each group).

Census team from 2003Although the Virunga gorillas increased in number between the time Dian Fossey began her pioneering conservation efforts in 1967 and the last census in 2003 – the only ape population known to have grown in recent decades – they have been in jeopardy for several years due to armed conflict in the DRC, including a recent outbreak in one sector of Virunga National Park. The 2003 census yielded an estimate of 380 individuals in Virunga National Park and Rwanda's Volcanoes National Park. This represented a 17 percent increase from the previous 1989 census. Two smaller populations, estimated at a total of 300 individuals, inhabit Bwindi Impenetrable National Park in southwest Uganda.

"The census is critical, because it not only provides a snapshot of the gorillas' current population size; it will also allow us to measure the success of our conservation programs and provide all the partners involved with a basis for sound conservation planning," says Karisoke Director Katie Fawcett, Ph.D.

The 2010 census is timed to occur at the end of the dry season, when tracking is easier but some rain provides water in the forest and tourism is no longer at its height. In addition, the security situation has improved. To ensure the likelihood of an accurate count, two sweeps of the area will take place over an eight-week period. The trackers will work in eight teams, with one team assigned to each sector. Team leaders and their assistants, including six of the Karisoke staff, will receive special training and all participants will be trained to use GPS and other scientific equipment and data sheets. The host countries will provide security.

While searching for signs of the gorillas, the teams will also collect data on other mammals in the parks and on human presence, including snares and traps, human tracks, poachers' camps and cut bamboo, firewood and building poles. In addition to serving as a tool for measuring the gorilla population, the dung samples will yield valuable information about the gorillas' health status and exposure to infection from humans. The samples will be tested for respiratory and other viruses and bacteria, and intestinal parasites. This will yield one of the most comprehensive health screenings of any wild ape population, and will allow comparisons between gorilla populations and between habituated and unhabituated groups. Finally, the Max Plank Institute for Evolutionary Anthropology will analyze the samples to determine paternity and genetic diversity, track lone males, and provide backup information to assure the accuracy of the census (so some individuals or groups are not counted twice).

Some census results are expected to be released shortly after the teams return from the forest. The genetic results will be available after six months, and a final report from the census is scheduled for publication in October.