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Rangers Assess Toll of Congo Conflict on Threatened Mountain Gorillas

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Science  19 Dec 2008:
Vol. 322, Issue 5909, pp. 1778
DOI: 10.1126/science.322.5909.1778
Collateral risk.

About 180 mountain gorillas, including this silverback called Karateka, live in an embattled national park.


In the wake of severe fighting in Virunga National Park in the Democratic Republic of the Congo (D.R.C.), worried rangers began a painstaking census late last month of the park's highly endangered mountain gorillas, nearly a third of the world's known population. “It is imperative to find out the gorillas' status,” says the park's director, Emmanuel de Merode, who is leading the census.

Violence in eastern D.R.C. worsened in October when government troops and allied militias clashed with rebels inside the 7800-square-kilometer park, which is Africa's oldest. About 400 park rangers and their families withdrew into temporary refugee status in a camp near the town of Goma.

After an agreement was reached to allow most rangers to return to the park in late November, de Merode—a Ph.D. anthropologist who became the park's director in August—organized a census to find out whether any gorillas succumbed. Last year, he says, nine of the park's approximately 180 gorillas were killed: one for its meat; one in a botched trafficking attempt; and seven “vindictive killings,” possibly by a corrupt army faction involved in illegal logging.

The census, expected to be completed by year's end, is focused on the park's 72 or so human-“habituated” gorillas, which rangers can track and recognize. “We identify the habituated gorillas primarily by unique wrinkles on their noses, which can be recorded as signatures,” de Merode told Science. Each morning, trackers follow forest trails to find a gorilla group; survey teams then try to identify all its members. Tragically, the habituated animals are “the most vulnerable,” de Merode says, partly because they “are closest to the forest's edge” and are less fearful of humans.

The nose-count approach has some technical weaknesses: It accurately counts only the habituated animals, about one-third of mountain gorillas in the park, and it depends on the trained eyes of certain rangers. “The fate of the unhabituated groups is unknown” in such nose-counts, says primatologist Martha M. Robbins of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. “Once the area is stable, it will be important to do a census of the entire region so we can get an estimate on the entire population.”

The densely populated and ethnically diverse eastern D.R.C. has been volatile for decades. Famed gorilla researcher Dian Fossey fled violence in the D.R.C. (then called Zaire) in 1967 to set up her Karisoke Research Center across the border in Rwanda; ever since then, researchers have tended to shun the D.R.C. in favor of outposts in adjacent countries. Although long-term gorilla research is ongoing at Karisoke and in Uganda, there has been a dearth of scientific studies on the D.R.C. side of the border. “The region has been too insecure” in the past decade, says Robbins, who worked at Karisoke before establishing the first long-term field study of mountain gorillas in Bwindi Impenetrable National Park in Uganda.

Hot zone.

Rebels occupy the gorilla sector of the Virunga National Park; other militias have entered from Rwanda.

The danger and lack of resources have so far impeded a more accurate count using techniques such as a “genetic census.” It involves a simultaneous sweep of the entire habitat by trackers who find gorilla tracks, identify nest sites, and collect fecal samples from which DNA is later analyzed to genotype every individual gorilla. So far, scientists have conducted a full genetic census of mountain gorillas only at the Bwindi park. In 2006, that census found evidence of 302 animals, 34 fewer than estimated using traditional methods.

Max Planck anthropologist Damien Caillaud, who studies the influence of habitat characteristics on the Bwindi mountain gorillas' social system, says the genetic census there “allows us not only to count the individuals but also to know their sex, the relatedness among individuals, … and the dispersal patterns.”

A 2003 census using traditional methods of the entire three-country Virunga Volcanoes area—funded by seven gorilla research and conservation groups—set the region's total population at 380 gorillas, including the 180 to 200 on the D.R.C. side. Together with the 300 or so mountain gorillas in nearby but separate Bwindi, that puts the total known population of the primates at nearly 700.

Although the D.R.C. rangers have now reentered Virunga park, the conflict continues, with some armed rebels entering from Rwanda. Whereas the major armed groups have outposts within the park's borders, a rebel group controls the gorilla area (Mikeno sector) in the park's southern region. As of last week, park rangers had fully surveyed two of the six habituated gorilla groups and found that new infants had increased their numbers. “The results so far have been pretty positive,” says de Merode, “but that can change.”

Robbins adds that the rangers “have risked their lives and worked through extremely difficult conditions to help protect the gorillas.” Researchers and conservationists alike hope that the wild inhabitants of Virunga park will make it safely to 2009, which has been declared the “Year of the Gorilla.”

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