By Josephine Gregory-Thomas
It's a spellbinding moment. Just ask the lucky visitors to the African rain forest who have silently watched a mountain gorilla family feeding or grooming only a few yards from them.
Such a meeting, however, cannot occur--at least not safely--unless the gorillas have been acclimated to human presence, a tedious, physically demanding and sometimes dangerous process that can take months or years. Yet habituation yields significant benefits, both to the animals and the people who live near their habitats.
No mountain gorillas exist in captivity, so the only way to see any of the just over 600 left on earth is to view them in one of the two areas where they live: Bwindi Impenetrable National Park in Uganda or in the Virunga Mountains, which includes Rwanda's Volcano National Park, Democratic Republic of Congo's Virunga National Park and Uganda's Mgahinga Gorilla National Park. Not surprisingly, the mountain gorillas are a prime tourist attraction, generating significant revenue that enables the park authorities to protect them and provides economic aid to surrounding communities.(While the parks in Congo and Rwanda are open to tourists they are temporarily closed for gorilla viewing.)
Visitors can only view gorilla groups that have adapted to people. "Habituation takes a very long time, typically one to two years," says Martha Robbins, a biologist who spent two summers in the wet, dense forests of Bwindi as a habituation volunteer.
The first step in the elaborate process is to identify a specific group and begin making daily contact with its members. This isn't as easy as it sounds.
"Gorillas make a trail as they move through the forest, pushing down and crushing vegetation" says Robbins, a professor at Gustavus Adolphus College in Minnesota. It takes training and experience to learn to follow these trails, tracking the groups that made them. Each day, trackers pick up the trail where they left it the day before and follow it until they again come close to the group.
"Gorillas make new nests every night," Robbins says, "so another way of making sure that trackers are following the same group consistently is to count the number of night nests along the trail. If the number of night nests found equals the number of gorillas in the group, then it is most likely the same group."
At first, gorillas flee at the slightest hint of a human presence. Trackers are careful not to follow closely, so that the gorillas will not fear they are being pursued. Instead, the trackers make vocalizations that mimic gorilla feeding and mating calls. After several months, the gorillas get used to the presence of people and may stop fleeing when approached. As a rule, however, it is many more months before they allow trackers even to catch a glimpse of them.
"Most tourists don't realize the hours spent just slogging through the forest day after day" to habituate the gorillas, says Robbins. "For many months, all the trackers may actually see of the gorillas is vegetation moving as the group takes off. So when they do get a good glimpse of the gorillas, it's a treat and it makes the whole thing worthwhile." Eventually, the gorillas tolerate the trackers coming within 100 feet of them for brief periods of time.
As the trackers move closer (the closest safe distance has been established at 16 feet), they might be charged by a silverback, or male leader, of the group; they withdraw, only to try again the next day. The day finally comes when the silverback stops his threats, and allows a few people to watch his group quietly and take photographs.
"The gorillas have learned that they are in no danger from humans who act in a very systematic way-mimicking gorilla vocalizations and avoiding loud noises and sudden movements," Robbins explains. But limits remain in place: Guides are careful not to let humans get too close to the animals, primarily to protect the gorillas from human infection.
"Essentially," Robbins says, "habituation is a lot of hard work with not much payoff initially, but once progress is made, it's well worth it. I found it a bit more adventuresome than going out to observe already habituated groups because we didn't know if we'd actually see the group, if they'd charge."
Despite the thrills Robbins adds: "Habituation is far from glamorous."
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