Martha M. Robbins
How Do We Study Apes in the Wild
Being a field biologist is often perceived as much easier and more glamorous than it actually is. Some people may even say that it is not "a real job." The image is of someone in khakis and safari hat confidently striding through the rain forest, notebook in hand, stopping frequently to glance through binoculars and jot down every move of the nearby apes. While we write down lots of things, we certainly don't write down everything we see. As with all scientists, we test particular hypotheses or predictions and use systematic methods and protocols that are designed to provide specific data. We then summarize our findings and write articles for journals that undergo scrutiny by our colleagues. In this way, we not only expand our knowledge but explain unexpected findings, which typically lead to even more questions and more research.
The challenge of fieldwork is that, as opposed to work in a laboratory, we cannot control, nor do we want to control, the natural environment. We want to observe the apes as themselves and have no or as little as possible influence on what they are doing. This poses the first difficulty: how do you obtain "natural, undisturbed" observations on wild animals that are inherently afraid of humans?
The main method used to get detailed observations on wild apes is to "habituate" them. What this means is that through repeated neutral contact with human observers, the apes gradually lose their fear of humans and will accept us watching them from close distances. Once habituated, the apes are still wild. We don't provide food for them or create any situation where they are reliant on humans for anything. They are not captive, nor do they become pets. Habituating some primates can take only a matter of months, but it takes years to habituate apes. It may take only one to two years to habituate mountain gorillas, whereas it can take five or ten years to habituate western gorillas, bonobos, or chimpanzees.
There are several reasons why it takes so long to habituate apes. The first challenge is to simply find the apes. If you aren't encountering any apes, you can't begin to habituate them. Gorillas and chimpanzees live at relatively low densities of only one to four individuals per square kilometer. Despite their large size, this translates into a low probability of simply bumping into them if you are walking through the forest. Therefore we rely on a variety of detective-work-style approaches. We look for any visual or auditory signs they may leave in the forest. In the case of chimpanzees, who regularly make very loud calls, it is useful to sit quietly in an area where you think they are, wait until you hear them call, and then try to find them. For gorillas, which are heavier animals than chimpanzees and spend more of their time foraging and resting on the ground, it is possible to see footprints and other signs, such as remains of plants that they have eaten or feces. Then you can "track" where they have moved through the forest, if you are skilled enough, given that the signs are often extremely subtle and difficult to see. Mountain gorillas live in forests where there is a dense understory of herbs and shrubs, so it is relatively easy to see where they have gone. This makes them much easier to track and contributes to why it is easier to habituate them. In contrast, western gorillas live in forests with little understory, so it is much more difficult to track them. In sum, it takes a tremendous amount of patience. Researchers often spend weeks or months searching for signs and getting only rare glimpses of a chimpanzee or gorilla.
Once you find the apes, the next step is to "convince" them that we mean no harm and that we are simply neutral factors in their environment. If the apes fear humans, however, they typically flee immediately upon seeing any observers. It can take months and months to see a change in behavior, in which a gorilla or a chimpanzee will wait a few minutes before running away, and then even more time before they will resume their normal behavior with people nearby. Because chimpanzees and bonobos live in fission-fusion societies, even though you may be meeting the same group daily, it is unlikely that you are seeing the same individuals every day, whereas with gorillas, which live in cohesive groups, you will meet the same individuals daily. This is one reason why it takes longer to habituate chimpanzees and bonobos than gorillas. Yet another issue to consider with gorillas is that if they feel threatened at a close distance, the silverback male will defend himself and his group by charging. It takes nerves of steel (and perhaps a little bit of insanity) to hold your ground and not run when a four-hundred-pound silverback is screaming and running directly toward you. However, these charges are primarily displays, because given the risk of getting hurt themselves, most animals do not actually want to attack. In any case, apes slowly become more accepting of humans, eventually developing "trust" of their human observers and allowing us to watch their lives.
Needless to say there are some risks to habituating great apes, and it is not an endeavor to be taken lightly. The very process of habituating wild apes causes them a great deal of stress and fear. By eliminating their fear of humans, we are, moreover, exposing habituated apes to the risk of poachers approaching and easily killing them. Therefore it is necessary to provide constant monitoring and protection to habituated apes. It is a long-term commitment. In addition, by coming in close contact with the apes, we are exposing them to diseases, particularly respiratory and intestinal ones, that they would not normally encounter or have resistance to. Old photographs of Dian Fossey grooming a gorilla may inspire many young scientists and tourists to want to do the same, but such interactions could lead to the gorilla dying. In the past decade or so, nearly all field sites have established health guidelines that include (to name a few) requiring all visitors to be vaccinated against many diseases, not allowing people to go into the forest if they are ill, following various hygiene procedures, and wearing surgical masks when near the apes. Some people may feel that these risks and the negative aspects of habituation do not justify ever doing it. However, all of the contributors to this book, as well as many other scientists and conservationists, believe that the benefits of being able to observe wild apes closely far outweigh the costs. For example, several studies have shown that the presence of researchers and/or ecotourism programs reduces poaching and other illegal activities. It is very difficult to get people interested in animals that they can't see or don't find attractive. By learning details of the social lives of great apes, people come to see the value of protecting them.
In addition to habituation, scientists use other indirect methods to study the great apes. We can gather a great deal of information about the apes' behavior by studying their forest and the remains that they leave behind. For example, much can be deduced about tool use by examining what look like sticks and rocks to the uninitiated, but in fact are brushes, probes, and hammers left behind by clever apes.
An unusual method of studying western gorillas involves sitting on a platform in a large clearing (called a bai) where the animals regularly come to feed on aquatic vegetation (see chapter 8). This method has the disadvantage of observations being possible only when the gorillas decide to go to the clearing, which may be as infrequently as once a month or less. The main advantage is that without habituation, if you have chosen a good bai, it is possible to monitor the group composition of ten or more social groups over the course of a year, which would take phenomenal effort through habituation.
To get the best understanding of ape ecology, in addition to studying what the apes eat and where they range, it is necessary to know what is actually in their environment. To do this, we are forced to become botanists and conduct detailed studies of food availability. This involves spending months and months counting and measuring the size of all herbs, shrubs, and trees in plots that represent only a small proportion of the forest. Because fruit is not found on trees all the time, we also set up "phenology studies," where we routinely check known individual trees for the presence of flowers, fruits, and young leaves. Typically, study sites monitor from 300 to 1,000 trees at least once a month.
The most unattractive item that apes leave behind actually provides a wealth of information: their dung. By sifting through feces, it is possible to learn a lot about what the animals have eaten. For example, if a gorilla eats fruit but doesn't crush the seeds, they are intact in its feces, and then we know which plant species it has eaten. Additionally, cells from the intestinal lining of an animal are excreted, making it possible to extract DNA and conduct genetic analysis from feces. This enables us to answer many questions that only a few decades ago were considered impossible to address with wild animals. Specifically, we can now determine the paternity of infants, as well as use genetics to know the whereabouts of individual animals that disperse out of habituated groups and are not physically seen regularly, but whose feces are occasionally found. Through genetic analysis we can also use feces to assist us in determining the number of apes in a particular location, which provides a more refined estimate than many other methods. Using feces to detect parasites has been done for decades, but new techniques are being developed to screen feces genetically for viruses and bacteria. This is opening up an entire new world of understanding the impact of disease on the apes, including the risk that humans pose to them. In an increasing number of ways, high-tech laboratory work is assisting wildlife biology.
In addition to the actual process of collecting data, there are many other unglamorous aspects of running a field site that are similar to many other jobs, albeit in a more remote, difficult environment. Nobody ever works entirely alone, so it is necessary to hire and manage local and international field assistants and students. Food and other supplies need to be purchased. Accommodation, which may be as basic as a tent or as relatively luxurious as a house, and vehicles or boats need to be maintained. Accounting for all expenses needs to be done. Obviously, money is necessary for all of this, so grants and reports need to be written to keep projects operating. Simply getting to the field sites is not easy. To reach any of the field sites discussed in this book takes anywhere from one to three days of travel from the national capital by some combination of car, boat, airplane, and foot.
The stories in this book convey aspects of the romantic image of the work, and the adventure and thrill aspects are definitely a part of what keeps us motivated. On a day-to-day basis, the fieldwork can be mundane as well as challenging. It often involves spending long hours recording very detailed data on animals that can be difficult to find, let alone observe. All is this is done come rain or shine, come marauding elephants or stinging nettles, come leeches or malaria. We spend years in the forest, because the apes are long-lived and not all aspects of their biology can be uncovered in a short period of time. The strict routine of scheduled work can also be interrupted at any point for a variety of unexpected reasons: poachers may come through the study site, making it necessary to notify the park authorities and remove snares; a field assistant may fall sick and need to be taken to a hospital that is several hours' drive away; a vehicle may break down, so that days are lost sitting around waiting for it to be repaired. Endless patience and flexibility are necessary.
Working in the forest is the easy part. Just as any scientist does, we spend innumerable tedious hours sitting in front of computers reviewing data, performing complex statistical analysis that reduces all the amazing beauty of the animals to a bunch of numbers, and writing very technical papers that receive thorough criticism from our peers. As conservationists, we may meet regularly with park authorities to provide advice on local issues, attend national and international conferences aimed at developing large-scale strategic plans, or develop educational materials for local schoolchildren and villagers to help them understand the value of protecting their neighbors the apes.
After hearing the challenges of habituating wild apes and working in remote locations, you may also be wondering why we don't simply study apes in captivity rather than go to all the trouble of habituation and working in difficult and isolated places. While captive settings are useful for some studies, such as experiments on the cognitive abilities of the apes, they are of limited use for understanding how animals have adapted to live in their natural environments. Who lives with whom, what they eat, and their "ecology" in a captive setting is determined by the zoo managers, not by the animals themselves. It is our hope that the explanations of the methods we've used and the stories that follow will convince you that we need to study and conserve apes in their natural, undisturbed environments. I'll end this chapter with a glimpse into what it is like to start a project with wild apes.
An Unexpected Sighting
"Are we wasting our time?" I wondered. What was the likelihood of finding any apes in this forest? I wasn't expecting actually to see gorillas or chimpanzees, but had dwindling hopes of even seeing signs of their presence, such as dung, torn scraps of vegetation, or footprints.
In 2003, Christophe Boesch and I were undertaking a month-long search in Gabon for a location to establish a new field site that contained both chimpanzees and gorillas. Despite decades of fieldwork at other locations in Africa, surprisingly little is known about the great apes found in the Congo Basin. We wanted a location where we could habituate the apes to our presence so that we could make detailed observations of their social behavior and ecological habits. Based on Christophe's twenty-five years of experience studying chimpanzees in Côte d'Ivoire and over a decade of my researching mountain gorillas in Uganda and Rwanda, our basic list of requirements for a suitable field site was short, but not easy to meet. We wanted a place that was not too remote, had no signs of poaching, was not under imminent threat of logging, and contained a healthy population of apes. Relatively speaking, Ivindo National Park met the first requirement. Whereas a hundred years ago, it would have taken Stanley, Livingston, or de Brazza weeks, if not months, to get from the coast to the depths of this forest, we had managed to get there with only a one-hour flight on a twenty-seater plane from the capital, Libreville, to Makokou, and then a five-hour boat ride down the Ivindo River to a scenic place to pitch our tents on its banks. Perhaps it was not as simple as arranging a picnic in a park, and I shouldn't understate what it takes to arrange such a trip, but we had been extremely fortunate with logistics. Following seemingly few emails and discussions with local conservationists and government officials, we had kindly been given a rough map of the area, information on a few places to camp, and the names of some local fishermen who would be happy to work as guides. After only one day of organizing in the frontier-style town of Makokou, voilà, we were loaded up with a ten-day supply of the fanciest nonperishable foods we could get, including such delicacies as oatmeal, rice, corned beef, and sardines, as well as plenty of energy and optimism, and we were on our way.
We had been told the Ivindo forest contained "naïve" apes-chimpanzees and gorillas that had had so little contact with humans that they would not fear us, but instead would be curious about the presence of an unknown, upright-walking ape, and thus presumably easier to habituate. Yet after a few ten-hour days of searching, we had seen few signs of apes or any large mammals, and it was clear that logging companies and poachers had discovered this forest before us. Machete cuts on saplings throughout the forest and the lack of bushpig were strong indications of heavy poaching. Monkeys gave alarm calls and fled immediately upon detecting us. We could see that elephants had previously frequented the forest based on the distinctive trails that they leave after decades of walking the same routes between favorite fruit trees, but we saw only a few in the flesh and some piles of old dung. The only hint of great apes was one aging pile of dung that might have been deposited by a gorilla, or perhaps by a buffalo. As we walked along a trail cut by loggers to get to the interior of the forest, I was further depressed by tree stumps of much greater diameter than my height. How much time had gone by from when those giant trees had been little seedlings until they were cut down in a matter of minutes? Presumably hundreds of years. As we passed yet more signs of poachers, I thought that the only naïve animal in this forest was us.
It was the morning of Day 6, and I was feeling pretty discouraged. It didn't help that although it was only 8 A.M., I was already hungry for lunch-hungry enough to start looking forward to a tin of oily sardines. My feet were wet because my boots hadn't dried out from a foray across a small stream the previous day. I had itchy mosquito and black-fly bites everywhere. I knew that to get through the day I should stop complaining to myself and be more positive about finding apes in this forest. Yes, it was pretty darned cool to be smack in the middle of the remote Congo Basin rain forest. Yes, the trees were huge and the forest was beautiful. Yes, maybe we'd see something interesting today ...
After a while, Christophe and I paused to decide on a route to bushwack through the forest. As we discussed this over the minimal map, amid the background noise of insects and birds, our conversation was abruptly interrupted by the low, distinctive hoo-hoo-hoo that could be only one animal. Chimpanzees! Based on the volume of the calls, the chimpanzees were surprisingly nearby, probably only a few hundred meters away. We were in luck-if we could locate them before they moved off.
Being the chimpanzee expert, Christophe automatically and without hesitation took a compass bearing and sprinted off in the direction of the chimp calls. I frantically ran after him. Chimpanzees can move fast and disappear instantaneously into the forest without leaving a trace. To catch up with wild chimpanzees requires a seemingly impossible combination of physical abilities: keep your eyes focused in the dim distance for quick detection of moving black shadows, keep a straight line course of the determined direction while dodging trees, and run as fast as you can over uneven ground without tripping on any vines, shrubs, or small holes, while remaining as quiet as possible, despite dry, crunchy leaves scattered everywhere on the forest floor. And then, once you get close enough for the chimpanzees see you, you need to slow down and nonchalantly become part of the forest. After about ten minutes, as I not-so-silently-or-gracefully flailed along, Christophe suddenly froze. I screeched to a halt just behind him, and after wiping the sweat from my eyes and disentangling my binoculars, which now had a stranglehold around my neck, I quickly detected movement ahead in several places.
My first reaction was of utter amazement that we had stumbled on any chimpanzees. My second reaction, being accustomed to quiet gorillas and only a novice with chimpanzees, was a desire to ask them to turn down the volume of their deafeningly loud hooting and hollering. Yes, we could hear them and so could every living thing within a kilometer. There is no sound like it; it fills the forest and amplifies, making it seem that there are many more chimpanzees present than there actually are. Whaaa-whoo! Whaa-whooo!! WHAA-WHOOO!!! Gorillas would never be so loud. My third thought was that, okay, we have gotten a glimpse of these chimpanzees, they've started to give alarm calls, and now they are going to take off before we can see much more than the outlines of their bodies. These chimpanzees were not habituated to seeing human observers at a close distance. But instead of our quickly seeing the backsides of fleeing chimpanzees, a performance expanded before us.
Immediately, we could see that there were many chimpanzees at various levels in the trees in front, to the left, and to the right of us. A huge adult male, with the hair on his arms erect to enlarge his appearance, stared down at us from fifteen meters above in a tree directly in front of us. He was one of three adult males we could see calling at the top of their voices while watching us from the trees. After a few minutes, two of the males nimbly descended from the trees and moved off into the forest. The third male climbed higher in his tree and continued to watch us. An adult female was in a tree thirty meters to the right side of us, clutching a small baby, who peered at us with wide eyes, pink face, and comically huge ears. She watched us nervously from behind a branch, then quickly bolted from the tree and vanished into the forest, with baby attached. Nearby, to the left, a juvenile descended a tree to get a better look at us, torn between his curiosity and his apprehension. He kept throwing glances between us and his mother, who was in the tree behind him. Finally, he climbed the tree containing his mother, and together they moved away in the canopy. Another adult female with a baby was barely visible as she silently sat partially hidden behind some foliage. Next, an adult male with a distinctive bald head dramatically jumped from tree to tree, first moving closer to us, then further away. A young female with a sleek, slender body and legs watched us briefly before slowly climbing down a tree and up another one. Without a doubt, the chimpanzees were curious about these creatures who had intruded on the privacy of their morning. Because there were so many chimpanzees and so much movement, it was difficult to decide where to look or even to try to keep track of which chimpanzee was moving where. Several of those that we initially saw ran away, but then others appeared from further behind or from high up in the trees. It was almost like the ebb and flow of the ocean, with some individuals moving closer to get a better look at us, while others edged back away from us. We counted at least twenty chimpanzees in all. All the while, the loud calls continued to echo through the forest. Eventually, the curtain fell on this drama, and each chimpanzee slowly and subtly melted into the forest.
As the last chimpanzee disappeared, the scientist in me took a look at my watch. I was surprised to see that only thirty minutes had passed since we first sighted them. It felt like an hour or two. I began to wonder whether these chimpanzees had ever seen humans before. Christophe and I didn't say anything to each other for several moments after the last chimpanzee disappeared. He generally keeps talk to a minimum in the forest, but I could sense that he was also impressed by what we had just seen. What do you say after a scene like that? Eventually, we compared notes of how many chimpanzees we had seen, their age and sex, their behavior, and then we continued on our way. I felt privileged to have seen those chimpanzees, not only because they were surviving in a very disturbed forest, but because it was such an extraordinary, extended view of so many unhabituated individuals. Yet they had given us a mere glimpse into their lives. It was almost like seeing a trailer for a good movie-you see the main characters and get a hint at the plot, but you want to see the entire show. We spent the next few days searching in the same vicinity of this chimpanzee contact, but without further luck.
Although we decided against Ivindo as a new field site, because of the high level of human disturbance in that locality, I have often wondered about those chimpanzees. Are they still out there? Poaching has undoubtedly continued in the forest. Moreover, a huge waterfall on the nearby Ivindo River was being dammed by a Chinese company to generate hydroelectricity. Great apes can survive in disturbed forests-but for how long and at what cost? And what about those chimpanzees as individuals? Whose peaceful morning feed had we rudely disturbed at that clump of fruiting trees? Who was friends with whom, and who felt animosity toward whom? Was the group's dominant male there? Had they come together simply to feed, or were several adult males pursuing the same adult female? How big was the community, especially given that we had seen twenty feeding together? We didn't know those chimpanzees. Although it is easy to garner concern for the threats facing the habituated apes we discuss in the following chapters, this glimpse into the lives of unhabituated chimpanzees serves as a reminder of the thousands of apes that are not habituated yet still face increasing threats to their survival.
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