White-eyelid mangabeys

Nazali koyekola Lingala with the commander of the forest

Three days ago I had to stay in camp because my stomach was struggling with an overload of bacteria which it is not accustomed to, which made me go to the toilet every hour or two. Just that day something extraordinary happened on the east. Kimya, an adult female, caught a juvenile black crested mangabey (Lophocebus aterrimus). All individuals present in the party gathered around her as she climbed in a tree and tried to get a piece of her prey. LuiKotale is the only field site where bonobos have been observed capturing and eating the meat of several species of monkeys. Ten years ago no one knew this type of hunting is part of the behavioural repertoire of bonobos. I hope there will be another opportunity for me to observe this spectacular behaviour.

After two days of confinement in camp, I craved going out in the forest again. Although it was our fixed rotational day off, and although we had an interesting visitor in camp, I decided to accompany Lovis, one of the local workers, on the afternoon shift in search of the bonobos’ nest site. When applying for this position, I had a lot of questions. What I particularly wanted to know, was how the teams that go into the forest are formed. This may seem strange, but there is a huge difference between going into the forest with another researcher or assistant and going into the forest accompanied only by local people. The cultural differences and the limited communication may sometimes provoke frustration, among both parties. For the Congolese the forest is the backyard in which they grew up. The workers like the work, they like the forest, but for most of them it is just their work, as their daily way of life. Of course, all western people come here with a different attitude and consider every hour as an opportunity to discover more about this magnificent forest.


However, the best way to get to know the culture and to learn the language of the local people is to go into the forest with one of them.So yesterday I agreed with Lovis to leave camp at 2 pm. Lovis is one of the two longest employed workers. One night during a party after too much Lotoko (the local brewed beer) he declared himself the commander of the forest, the man who knows the forest. And he certainly knows the forest.

On the swampy Kossiwa trail less than a kilometer from camp he spotted a fresh footprint track of a leopard (Panthera pardus). The next kilometer he picked out some bonobo food trees to teach me their local names. After we entered the home range of our bonobo community he stopped a first time to listen. I heard nothing but the familiar background forest sounds. Lovis whispered: “mbengene”. We stayed put and thirty seconds later a Weyns’ duiker (Cephalophus weynsi) wanted to cross the trail twenty meters from us. As soon as it saw us through the undergrowth vegetation the duiker flashed away. I commented what happened and whispered: “Njama akimi”.

A few kilometers further we sat down, tofanda, to listen for bonobos. In silence we went through the bird guide and every few pages I asked him: “Oyebi ndeke oyo?” If he knew the bird, Lovis would answer with its local name.

Another aim of our shift together was to do some gps training. The workers always take a gps with them in the forest, but not all of them know how to work with it. Last year I did training of bonobo trackers of the Congolese ngo Mbou-Mon-Tour, so it’s not the first time I do this. Teaching African people how to use a gps is not always an easy task and requires a lot of repetition, checking if they really understood it and, most of all, you need a lot of patience. But Lovis picked up very fast how the track log function of a gps works. I congratulated him and told him he is a smart guy, ozali mayele mingi, and the sometimes grumpy worker put up a big smile. While walking further south Lovis thanked me for showing him how to use the gps, matongo mingi. I replied he was a good Lingala teacher.

By the end of our shift Lovis started to ask the typical questions. I answered I have two brothers and two sisters. Lovis is also part of a family of five, but he is the “grand frère” while I’m the mwana ya samba. He continued his questions. No, like most mindele at LuiKotale I’m not married. I explained him that in Mpoto people often marry at a later age. Also, for mindele coming here it is not always easy to combine field work with normal social life at home. Lovis replied: “Nayoki”, I understand. He told me that in the past he spent several years at Maluku, a city port near the Congo River, and in Kikwit, a big city in the south. If you travel and come across a place with good opportunities to work, you should stay a bit longer to earn money so you can have a good future for your family. “Mpo na sima malamu.” Eventually Lovis decided to go back to his village to live with his mother, brothers and sisters again, and the villagers he grew up with. Sometimes you have to sacrifice things, “mais azali mabe te”, because these sacrifices are needed to benefit your life later on. “C’est la vie!”

Although our cultural attitudes are quite different and although I came here for another reason than money, I felt Lovis understood what I meant by saying it is not always easy to be more than 6000km away from friends, family and the normal, comfortable world we are so familiar to. The commander of the forest was not successful in finding bonobos that day, but I didn’t mind. I spent an afternoon in the forest and got some good advice from my new Congolese moninga. On our way back to camp I realized how privileged I am to get to know the true Congolese people and their culture and it made me forget the sacrifices.


A day in the life of a habituator

People also celebrate Christmas and New Year in Congo. On Christmas, we had a relaxing day in camp with pancakes in the morning, chilli con carne with bread at lunch and calzone with chicken for dinner. We made a bit too much food and since we of course don’t have a fridge here, everyone had to do an effort to finish it. On New Year’s Eve, all local people had left camp to celebrate “la fête” in the village. We enjoyed the quietness in camp and the bean and rice burgers with guacamole and delicious little breads. All of that made on a simple wood fire with simple ingredients, it was just heaven.

For the rest of this post I want to tell you a bit more about my work as a habituator. Habituation is a term used in primatology for the process of accustoming wild animals to the presence of observers. It is defined as the relatively persistent waning of a response as a result of repeated stimulation that is not followed by any kind of reinforcement. In other words, repeated neutral contact between wild primates and human observers leads to a reduction in fear, and ultimately the ignoring of the observers. Habituation is a necessary step for the detailed study of ecology and behaviour in the wild. Observing primates directly without having an influence on their behaviour can learn us much about how they really are. Some species are more difficult to habituate then others. Species exhibiting wide-ranging behaviour, or species that don’t leave a lot of traces, are difficult to find and hence, difficult to habituate. Semi-terrestrial species or those living in dense habitats are not easy subjects either, as individuals will flee before you come close enough to observe them. For habituation to succeed, one needs to make repeated contact with the same individuals. Therefore, species with a fission-fusion social system or groups of very large size are again difficult to habituate. Great apes, along with mandrills (with groups of up to 800 individuals) and the semi-terrestrial white-eyelid mangabeys, are among the most difficult to habituate. You need an investment of several years and a lot of patience for bonobo habituation to be successful.

Yesterday Lovis, one of the local trackers, went into the forest in the afternoon to try to locate the nest site of a bonobo party by listening for their vocalizations. After dark, he arrived back in camp and gave us the location. Our bonobos were “nested” that evening, so I went to bed around 19h30. The next day we left camp at 4h00 for a 1-hour walk. We arrived on time at Bompusa 3250, where Lovis had pulled a cotton thread from the nest site to the trail. We backtracked the string of 90m, an easy one, to reach the trees where the bonobos had built their sleeping nests the evening before. It was 4h59 and, quite unusual, some bonobos were already awake. Not because of our arrival, but maybe the bright moon made them decide to leave their nest half an hour earlier than usual. At 5h24 one of the last bonobos left his nest and headed to a maku tree fifty meters further. Bonobos eat maku fruits year-round and almost every day. After a quick breakfast the individuals we were observing joined the ones thirty meters ahead in another maku tree. At 6h03 the whole party started moving further south and it was difficult to follow them. The individuals in our community are not yet fully habituated. When you approach them within 10 or 15 meters, they will move on, which makes it difficult to follow them on the ground. Luckily, bonobos vocalize regularly to make contact with other parties in the surroundings. So after we lost them for fifteen minutes, we found them again at 6h24 at one of their current favorite feeding trees about 300 meters further southwest. They were now feeding in a gigantic bopfunga tree of over 40 meters high. The thick and high canopy made it difficult to see who was in the tree, but fruits came down continuously, which indicated there were several individuals. After some resting, the party started to move to another tree at 7h24. With my binoculars I could see them all taking the same route along some lianas. I noted three adult males and several adult females of which I could recognize two. Some individuals have a very distinct face or have some missing toes or fingers, but for adult females we mainly use the size and shape of the sexual swelling to distinguish them from one another. Bonobos have sexual swellings to advertise their sexual receptiveness to males, just like chimpanzees, baboons, macaques, mangabeys and other species do. When they are feeding high up in a tree, this swelling is the most useful feature to recognize the females. After feeding in an unkown pod tree nearby from 7h30 to 7h47, the party descended to the ground and climbed the steep hill further to the south. We lost them out of sight, but stuck to the south-western bearing they were following. We listened on our way for branches moving or fruits coming down a tree, but without success. When we stopped near a tree fall at 8h14, we heard a soft weeping call and the smacking sounds of bonobos grooming each other. At times bonobos can be very quiet. The party we were following had settled down on the tree fall and was enjoying the beautiful morning. When they left the scene at 8h28, it was not clear to us in which direction they had gone and we didn’t see them again for the rest of the morning.

Habituation of wild animals entails certain risks, mostly for the animals. During the habituation process the level of stress caused by our presence is of course considerable, but this decreases as habituation continues. Even when habituation is complete, there is the risk of disease transmission, from humans to the habituated primates. That is why we always wear surgical masks when near the bonobos and why we don’t enter the forest when feeling sick. A simple cold can cause a severe infection and ultimately death among wild great apes and we definitely want to avoid that.

Around camp we have several “camp pets”, wild animals which are passively habituated to our presence in and around camp. In the forest office a bit further in the forest, you can regularly see blue duikers (Philantomba monticola) who walk slowly past. They know we are there, but don’t seem to bother about that human being sitting in a chair or lying in a hammock. I have had a male-female pair at three meters from me. At night we may come across a brush-tailed porcupine (Atherurus africanus) or a water chevrotain (Hyemoscus aquaticus) near our garbage bin and near the toilet an African civet (Civettictis civetta) is often seen. It always feels special to meet these fearless animals in our normal living space.

The smaller creatures of the forest

I know I haven’t written a lot lately, just because there was not so much to write about. Of course a tropical rainforest is never boring and in the meantime I have seen the bonobos more often. I’m starting to recognize more individuals and have seen several interesting behaviours, but more about that later. What follows is an account on the smaller creatures of the forest.

Spiders are everywhere, especially in a tropical rainforest. When walking off-trail through the forest, my head often gets caught in the web of a spider. The most wonderful spiders actually live in our camp. The edge of the camp is planted with pineapple plants, which provide us with a good daily supply of delicious pineapples at the moment. One of the pineapple corners is also home to a colony of Nephila spiders. Most spiders build a new nest each day, but these colonially living spiders form huge, relatively permanent structures of several meters in diameter. The spiders also include debris in their webs. At first one thought this debris consisted of decomposed prey items, but actually the debris turned out to be rotting plant material. By incorporating plant material in their web, the spiders in a colony work together to increase the chance of attracting and capturing prey. Another advantage of living in aggregation is the structure itself. Certain bird species have specialized in stealing prey from spider webs and most birds use the silk of spider webs as glue to build their nest. The individuals in the center of the aggregation may be at lower risk of predation or parasitism by birds. Maybe the colony that chose our camp as their base is even less prone to these risks as there are always people around who discourage birds to come closer. In fact, it seems the spiders are encroaching further upon our camp.

In the forest you also regularly find millipedes. Giant millipedes of up to twenty centimeters. I noticed there are several species here. When disturbed, they curl up and wait till the coast is clear. I don’t see as many termites compared to at Bai Hokou, I would say, but you can’t miss the mounds they build to house the colony in every shape and size. Of course there are also less enjoyable critters in the forest. Today while searching for bonobos we crossed a massive trail of driver ants on our path. It can be quite painful when the ants actually follow the trail and you realize this too late. Not so today, we just ran across the moving colony and stamped our feet to get rid of the ones that had clamped to our sandals. As often with variable success. After a while we took back the same trail as we heard bonobos from the direction we came from. With our compass and GPS we tried to estimate the location from where we heard the vocalizations and we realized it would be close to where we had encountered the ants. When we approached the unstoppable colony, we decided to go off-trail in the direction of our guess. Bad choice. After some meters we came across another part of the colony, but this time they were unavoidable. Everywhere around us were ants. We crawled through a thick liana patch, back to trail, but in the meantime both Leanne and I had ants everywhere on our feet, legs, head and everywhere in between. It took us a while to get rid of all the ants on our body. This was my worst ant experience so far in Africa, although I consider myself lucky to never have experienced an invasion of driver ants in camp. Let’s hope I will never wake up with ants everywhere in and around my tent, gnawing on my precious chocolate. A nightmare, when I think about it. Hmm, I think I will put my chocolate in a safer place tonight.

Two mysterious creatures roaming the dense forests of Central Africa

We haven’t been very successful in finding bonobos on the east side lately. The rain has hampered our effort and maybe the bonobos are more focusing on fruit trees in the swampy areas along the Bompusa river, where it is harder to find them (and where elephants are more present). The big rains of last week have transformed the trail across the Bompusa into a real swamp with almost knee-deep water. By now my feet have adapted to walking in sandals through wet terrain for several kilometers a day. Despite the rain and not finding bonobos, camp life has been very nice last week. Several people have made bread, soup, cakes and chapattis for Thanksgiving and other occasions. Our kitchen is just an open fire and a couple of pots, but it’s amazing how creative one becomes when confronted with a very basic diet every day.

One morning in the forest we came across several freshly dug holes near the trail. It seemed a large animal was trying to make a burrow on this spot. Would it be an aardvark, a giant pangolin or simply a red river hog? We decided to install a camera trap and the following night we recorded several pictures of an aardvark (Orycteropus afer). Probably few people would ever expect an aardvark to live in the dense forests of Central Africa. However, this habitat with a year-round abundance of ants and termites is very suitable for the species. Little is known about these nocturnal creatures roaming the forests of Central Africa. Some scientists believe that several species of aardvark exist. If true, I expect the forest ones to be clearly different from aardvarks living in the savannahs of East and Southern Africa.

Today we went to the forest at six o’clock to search for bonobos. Upon arriving at one of our usual listening spots it started drizzling and some minutes later the real rain came in. We waited for two hours, but finally decided to head back to camp. It looked like the morning shift had been useless, but on our way back we stumbled upon a tortoise. The only species inhabiting Central Africa is the forest hinge-backed tortoise (Kinixys erosa). Earlier this year I trained the trackers of a Congolese ngo, called Mbou-Mon-Tour, working for the conservation of bonobos near the city of Bolobo (by the way, this city probably gave rise to the name of the great apes we are following at LuiKotale). I had contacted a tortoise researcher about marking individuals in the field before I went to Bolobo. Here in LuiKotale I also brought the materials needed for this simple method: a small metal saw blade and a file. Hinge-backed tortoises have 13 marginal scutes, each one is given a different value (see figure).


Using the saw and file we engraved a distinct man-made notch in the scute with value one, while the rain was pouring down. The carapax of a turtle is made of the same material as human hair and nails (keratin), so notching is completely unharmful. The flat underside indicated that our tortoise was a female and we recorded its size and location. When we find this individual again, we will be able to identify it as female 001. Over a long time span one could gather interesting data on density, survival and ranging patterns of these mysterious reptiles. I have to note that the chance of encountering tortoises in the forest is low and probably next time we see one, it will be when chasing bonobos, so we won’t have time to look at a stone-like thing on the ground. But who knows, maybe we might learn something about the ecology of this little-known species. Since the work of Schmidt in 1919 in DR Congo, no one has published detailed information on the species. IUCN (the World Conservation Union) does not have enough data on its distribution, local densities and ecology to determine its conservation status (“Data Deficient”). Schmidt provided data on morphometrics, clutch size and egg size and considered it to be omnivorous, “eating plants, insects and other arthropods and carrion”. It is said to be fond of fungi. Tortoises are traditionally consumed by local people all over Central Africa (see picture), so information obtained by a simple notching system might prove useful for conservation one day.

Tortoise marking_hunt

Why the elephant is not my favorite animal

Recently I have been able to expand my mammal list with a few more spectacular species, including two primate species. The first days after arriving at LuiKotale I had already seen red-tailed monkeys and a large group of red colobus monkeys less than one hundred meters from camp. The red colobus didn’t seem to bother much about my presence, the perfect situation to take pictures. Yesterday I was sitting under a mosquito net to escape from the bees in camp, when I heard branch shaking. A group of Angolan black-and-white colobus monkeys (Colobus angolensis angolensis) was crossing a tree gap closeby. This is one of the less frequently encountered species here. The other day in the forest we stopped along the major trail of the east side to discuss another bonobo or forest issue, when we heard a noise in a tree nearby. We couldn’t see a thing, but there was clearly a large animal coming down to the ground. Leanne, who was showing me around, vaguely saw a second leopard taking the same steps down to the ground and a few seconds later we heard a soft grunt/cough twenty meters from us. We had obviously disturbed these two big cats, so we decided to back off silently.

Searching for bonobos in the forest mostly relies on good hearing. You go to the areas where you anticipate them to be, based on their ranging behaviour of previous days and fresh traces, and then you only have to wait and listen. On my first search day we were lucky and the bonobos happened to be in a fruit tree just one hundred meters from our first listening spot. Bonobos have a fission-fusion social system. This means a group of bonobos, called a community, regularly splits up in parties of varying size and composition which can join and split again during the course of several hours or days. The bonobos in the east are not yet fully habituated. When they descend to the ground it is difficult to approach and follow them closely. Next days and weeks I will focus on identification of all members of the community.

After feeding for a while in a tree the subgroup we were following moved further through a very dense patch of forest. Between 9 and 10 am the adults usually rest, while the juveniles are playing. A young female was chewing on the inner fibers of a liana. The nutritional value of these fibers can’t be that high, so probably some other properties make this food type interesting for bonobos. After the daily rest, we lost sight of the group as they went further east, towards the swampy area along the Bompusa River. The forest we were crawling through was very dense, with a lot of lianas. The further east we went, the more traces of elephants crossed our path. The day before I had walked the “big tour”, a hike of more than 20km along the major trails of the study area with a stop at a marshy forest clearing in the south. On the Nkuma trail from west to east and across the Bompusa River and the swamps at either side, we had come across a lot of elephant traces. In total I counted 25 fresh piles of elephant dung and loads of footprints in the knee-deep mud, indicating that this area is heavily used by forest elephants. When trying to follow bonobos in the forest after you have lost them, you regularly stop to listen for their vocalizations or movement in the trees.

That day we were clearly encountering fresh traces of several elephants, so the situation was tense. We stopped close to a tree fall on our right side. Leanne was just about to walk further when she saw an elephant ten meters in front of us. She whispered “elephant”, although I can’t really remember that. It all went very fast, but I think I saw the silhouette of the elephant as well and I immediately started to run in the opposite direction at the same time as Leanne did. We ran as fast as we could through dense vegetation, but luckily the elephant didn’t charge. Leanne and I both have stayed several months at Bai Hokou in the Central African Republic, where elephants pose a real threat. Most people in camp would love to see an elephant and we, the only two who don’t want to see them, are among the few to have seen elephants in the forest. Elephants are rare at LuiKotale, so let’s hope I won’t see another one for the rest of my stay.

Lieven in congo

At the moment Lieven Devreese is staying at LuiKotale, a bonobo research site of the Max Planck Institute for Evolutionary Anthropology in the vicinity of Salonga National Park, Democratic Republic of Congo. Lieven is a research assistant working on habituation of a second group of bonobos and he hopes to get to see some golden-bellied mangabeys as well. Here you can read more about his 10-month adventure.