Studying wild chimpanzees in Taï National Park

May 03, 2013

West Africa, the Republic of Côte d’Ivoire, Taï National Park, not far from the border with Liberia: the Max Planck researchers’ camp is located in the middle of a tropical rain forest, a twelve-hour car journey from the seaport of Abidjan, three hours of which involve travelling along a dirt road from the nearest village. Scientists working with Swiss primatology researcher Christophe Boesch have been studying chimpanzees, which are native to this virgin forest, for over 30 years. The camp has belonged to the Max Planck Institute for Evolutionary Anthropology in Leipzig since 1997.

The road – if the muddy track, which is often barely navigable in the rainy season, even with a modern all-terrain vehicle, can be called that – leads to the North Camp, from which the three actual research camps can be reached on foot. Albeit, following a rather long stopover: all who comes to the camp – irrespective whether they are arriving for the first time or are returning from a visit to the “outside world” – must spend five days in the North Camp before they can enter the research area. This quarantine is an essential precaution, as diseases introduced by humans pose one of the greatest threats to the lives of the chimpanzees.

The Max Planck scientists study three habituated - animals, namely, that are used to the presence of humans -neighbouring groups of chimpanzees which comprise a total of around 100 animals. One of the researchers’ objectives is to learn about and document the lives of the Taï chimpanzees in their natural habitat in detail. “Chimpanzees resemble us in many respects,” says Christophe Boesch, Director of the Department of Primatology at the Max Planck Institute for Evolutionary Anthropology and founder and long-time head of the chimpanzee project. “By studying these similarities in our nearest relatives in their natural habitat in Africa, we can learn more about the evolutionary roots of culture. Which, of course, is a key element of our identity as humans.”

Ultimately, it is about answering the question as to what makes humans human. Are we unique in our capacity for developing traditions and cultures and passing them on to our offspring? Or do chimpanzees also have social traditions, i.e. differences in behaviour that are not genetically programmed and cannot be explained by ecological conditions, and are passed on from generation to generation within a group? The Max Planck Institute’s research station in Taï National Park provides optimal conditions for researching these questions. The scientists can observe chimpanzee groups, which are very similar to each other genetically and live in close proximity under similar ecological conditions.

It is equally important for the researchers, however, to record basic information about the total number of chimpanzees, the group size and composition of the groups in the National Park. It is not currently known exactly how many of the great apes actually still exist in the wild – exact population sizes are not known for chimpanzees, bonobos and gorillas in Africa or for the orang-utans in Asia. Such basic information is urgently required to provide scientifically validated assessments of the impacts of natural changes and the success of nature conservation measures.

The scientists from Leipzig are very familiar with the rain forest of the Taï National Park. Some of them, like Christophe Boesch and Tobias Deschner, one of his closest collaborators, have been coming here for decades; others – students and doctoral candidates – for several months at least. Around 20 researchers currently live and work in the camp: they include experienced scientists, doctoral candidates, students and local field research assistants. There are also a few people who look after the researchers’ practical needs, for example a driver who brings them food once a week and undertakes all of the necessary journeys to the nearest village and the seaport of Abidjan.

The permanently resident team at the Max Planck camp also includes a vet. He has a simple molecular biology laboratory in the North Camp which includes a PCR machine for the replication of the smallest traces of DNA. In this way he can check the animals’ health regularly and document it; should an animal fall ill, he can quickly establish the cause. He also carries out routine checks on the arrivals at the North Camp for respiratory disease pathogens which pose a particularly serious threat to the chimpanzees. A seemingly healthy human can harbour such pathogens and trigger a life-threatening epidemic among the apes. In general, however, sick chimpanzees are not treated by the vet as, despite the presence of the researchers, it is intended that they remain wild animals, and that their lives are influenced as little as possible by the presence of the scientists. The treatment of diseases introduced by humans is an exception to this rule.

Observing the behaviour of chimpanzees living in the wild

To be able to observe the behaviour of apes in their natural environment, the researchers must accustom the animals to the presence of humans until they take no further notice of them – this process is referred to as “habituation”. However, before it can even begin, the scientists must locate the animals. To put it in purely mathematical terms, less than one chimpanzee inhabits an area of ten square kilometres in the Taï National Park. Therefore, the animals do not simply cross the scientists’ paths. The only option open to them is to comb the forest as quietly and inconspicuously as possible and look for the traces they leave behind: discarded fruit peel, chewed plants, footprints, droppings and abandoned sleep nests in the trees. Fortunately, chimpanzees often make a lot of noise – when they are heard, their calls can be followed over long distances.

The researchers establish regular contact with the apes by carefully approaching a group. When the chimpanzees tolerate the presence of the researchers and do not flee as soon as they notice them, the first objective has been attained. Gradually, the individual members of the group develop trust and accept – often only after months of patient approaches – that there are humans in their immediate proximity. Chimpanzees do not live in defined groups like gorillas, but in so-called fission-fusion societies: smaller, new sub-groups constantly form within the community which, in turn, disband and re-combine. Consequently, it can take a long time until all of the individuals become equally accustomed to the presence of the people and take no further notice of them. It generally takes five years for a group of chimpanzees to accept the presence of the researchers as “normal” and for the animals to behave in their presence as though they were alone – only then can the actual research begin. This, too, makes habituated chimpanzee groups, like those in Taï National Park, particularly valuable for primatology research.

The scientists’ main objective is to observe the natural behaviour of apes; they would like to get to know their “everyday life” in the jungle. Their own behaviour is therefore constantly aimed at influencing that of the animals as little as possible. They act in a completely neutral way towards the chimpanzees: they do not feed them, they do not eat in their presence and never come into physical contact with them. Moreover, they do not play with the young animals, even if the latter are curious and try to establish contact with them. However, they follow the chimpanzees everywhere and observe them.

The humans do not try to become members of the chimpanzee groups either – on the contrary, they adapt their behaviour to ensure that, while the apes accept their proximity, they otherwise ignore them. This strategy is not only in the interest of the research, but also that of the scientists’ safety. For if the observers were viewed as equals by the apes, they would inevitably become involved in status struggles – which would be fatal for the researchers, as an adult chimpanzee is considerably stronger than an adult male human.

The scientists also take considerable care not to be perceived as food competitors by the animals. They do not eat any fruit or collect any nuts in the chimpanzee’s territory; the rich food supply of the tropical forest is out of bounds for them. All of their food is brought in from outside. Waste disposal is equally rigorous; all compostable waste is carefully buried and the rest is taken to the nearest village. “We don’t even spit in the forest,” says Tobias Deschner. The risk that the animals could be infected with a human disease is too serious: in 2009, numerous apes died in a cold epidemic.

Human diseases represent one of the greatest threats to the apes. On the one hand, they are so closely related to us that they can easily be infected with our diseases. On the other hand, the immune system of apes that have not had any previous contact with humans is completely unprepared for the viruses and bacteria that affect humans. Thus, such an infection can have disastrous consequences. The danger is particularly significant in locations in which timber companies, bush meat hunters and farmers use the jungle; however, close contact with a researcher could also prove to be one contact too many for a chimpanzee group – for example, in the event of the transmission of rhinoviruses. A cold that causes little or no harm to an infected human can easily cost an entire family of chimpanzees their lives.

For that reason, everyone in the camp must comply with strict hygiene rules in their interaction with the chimpanzees; these rules – also based on bitter experience in the early years of the research - were developed in cooperation with the Robert Koch Institute in Berlin. The five-day quarantine in the North Camp is just the beginning of the process. Each researcher and visitor must be vaccinated against a number of diseases and no person who presents even slight signs of an infection may enter the forest. Each observer constantly maintains a distance of at least seven metres from the apes and always wears a facemask – even if this is highly unpleasant in conditions of 95 percent humidity and temperatures in excess of 30°C.

Needless to say, all of these rules also applied to the film team during the shooting of the Chimpanzee film. The Disney team made repeated visits to the Max Planck Camp for over three years. The film crew constructed a new hut next to that of the scientists in the South Camp and moved in with lots of equipment, generators and boxes of food. However, despite all of their ultra-modern equipment: without the knowledge, experience and help of the scientists, they could not have made their film. Long before daybreak the scientists set off to look for the chimpanzees’ sleep nests. Using walkie-talkies they maintained contact with the camera team and told them where to go. They also taught them how they had to behave to get the apes to appear before the camera in their natural habitat.

On the move with the chimpanzees in the jungle

As the researchers in Taï National Park have proven scientifically, chimpanzees have an excellent spatial memory. They roam around large areas and have no problem locating widely dispersed food trees and their other favourite places. The humans in the jungle prefer to rely on modern technology for navigation. When the chimpanzee group has decided on a night camp and built its sleep nests high in the trees, the observers record its exact GPS coordinates. This makes it relatively easy to find the animals again the next morning, as the group does not usually move during the night. Depending on the distance of the sleeping place from the camp, this means that the researchers have to get up at 3 or 4 a.m., fortify themselves with a hearty breakfast to fuel them for the demanding day ahead, and embark on a hike through the almost impassable jungle lasting several hours. The most important thing is that they are back on location at sunrise. Because if they are not there before the chimpanzees wake up and begin their search for food, they will usually lose sight of the group: chimpanzees travel considerable distances in short periods of time. It can take days or even weeks to find a group again, and only those who can correctly interpret the animals’ highly inconspicuous tracks will have any chance at all of finding the apes in the forest. The specialist skills and the considerable experience of the Ivoirien field assistants are very important here. However, it is far easier to stick with the animals in the first place. Thus, the researchers try to follow each of the observed groups every day whenever possible.

A chimpanzee group is usually accompanied by two to three researchers; the field assistants observe an individual animal, in particular, and record general observations while the students and doctoral candidates investigate particular questions. But following a group of chimpanzees through the dense rain forest is easier said than done: with their compact posture, the chimpanzees move with incredible agility on their hands and feet, while the erect bipeds stumble over roots and thorny undergrowth, get entangled in lianas and sometimes have the feeling that they are standing in front of an impenetrable green wall. In addition they have to keep the animals, which appear to melt into the vegetation in the sparse jungle light, in their sights. Despite all their efforts, in many cases all they can do is listen for the calls of the chimpanzees and hope that the group will soon stop for a break.

Everyday research life in the national park

Everyday research life in Taï National Park does not consist exclusively in the observation of chimpanzees: the scientists also use numerous indirect methods to find out more about them. They look for sticks, stones and other objects that the chimpanzees have used as tools and spend a lot of time becoming well acquainted with the animals’ habitat. They identify the plants and analyse the apes’ food spectrum. They know exactly which fruits the chimpanzees particularly value, and when the fruit on such a tree in a group’s range is ripe. The chimpanzees’ droppings are a particularly informative source for the researchers and they regularly take samples from them. They can reveal a lot of information, not only about the animals’ eating habits. Because cells from the chimpanzees’ intestinal wall are also excreted with the droppings, the scientists can isolate DNA from them and carry out genetic analyses. In this way, the kinship relationships within a group can be clearly and definitively identified. For example, today, it is no longer a matter of assumption which young animal is the offspring of which male ape – the researchers can verify this exactly. Together with information about the animals’ hormone balance, which the scientists obtain from the analysis of urine samples, and combined with the carefully documented behaviour observations, many conclusions can be drawn on the family and social behaviour of a chimpanzee group. For example, it is far from the case that all of the young are the offspring of alpha males but, depending on the group, they are also fathered by lower-status males with varying frequency. As the researchers discovered, various strategies for reproductive success exist among chimpanzees, particularly for non-dominant males. The females also adopt individual strategies to ensure the best possible outcomes for themselves and their offspring.

The DNA analyses of droppings and hairs from abandoned sleep nests also provide important data for the counting of the animals in the rainforest. Based on these, it can now be stated with greater accuracy than before how many individuals live in a forest area and whether animals that have left the group, and have not been seen by the researchers for a long time, are still alive.

Some of these tests can be carried out directly at the camp; however, most of the samples are conserved in liquid nitrogen and transported to Leipzig on dry ice where they are analysed using the very latest technology at the laboratory of the Max Planck Institute for Evolutionary Anthropology. Moreover, all samples are stored there in the long-term in a biobank. This means that other factors can be investigated at a later date – perhaps using even better test methods that have not yet been developed today.

Contact with the outside world

Due to the strict hygiene measures it has become difficult for the scientists to leave the camp for a short time and travel to the nearest village. For any scientist, the loss of five days’ research is too high a price to pay for going for a beer at the local bar. However, the people in the camp are not completely cut off from the outside world. Every three days, a stable Internet connection is established via a satellite telephone, via which the e-mails that have collected in the intervening period can be exchanged. Not only are numerous scientific data sent back and forth, the scientists are also able to maintain contact with their family and friends throughout the world. Modern communication technology also does not come to a halt in the African bush. The mobile telephone reception in the camp is pretty good at times: until recently, it was necessary to travel 20 kilometres to the next village to make a telephone call; today, depending on the camp, it is sufficient to climb a nearby hill or climb a ladder to do so.

In contrast, the local field assistants leave the camp regularly. They work fixed three-week shifts and always return to their home villages in between. In addition to their work in the forest, they have assumed another equally important task: they act as the advocates for the chimpanzees in their villages. They report about their work, relate everything they have learned about chimpanzees and, above all, describe the surprising and fascinating experiences they have had with the individual animals. In this way, they make a crucial contribution to the protection of the chimpanzee groups against poaching. The field research assistants are not the only Africans on the Max Planck team. African students are often also involved in the projects. It is hoped that as fully trained scientists they will assume the role of guarantors for the protection of the National Park and the continuation of the research projects – if possible, irrespective of the country’s political situation. For nothing is more threatening to the survival of the apes than political unrest: in a country torn by civil war or other conflict, there is no lobby to protect the interests of apes in the wild.

Mud, incessant rain, almost impenetrable vegetation, parasites – everyday research life far from civilisation is often difficult and not always pleasant. And yet, for many scientists, the rain forest is a paradise on earth. “The chimpanzees in the Taï are part of my life. I have spent more time with some of them than with my closest friends. They are free here, and to experience them in their natural habitat is a true pleasure,” says Tobias Deschner.

Andrea Wegener

Go to Editor View