One of the pleasures of field work
For the rest of my stay in the field I am planning to do a small research project on the bonobo community in the east. Habituation level is not perfect, so we have to take some limiting factors into account, but it should be possible at this stage to collect the first detailed data.
To become more familiar with bonobo work, the possibilities of research and how people do it, Gottfried suggested that I should occasionally go to the fully habituated bonobos in the west. This community is being followed since 2002 and all individuals tolerate humans within ten meters. Yesterday, Sarah and I left camp around 11:00 after the morning team sent a text message to the camp satellite phone. Based on their location and direction of travel we predicted where we would find the bonobos. On our way we heard bonobos close by, but when Sarah produced a “whoop”, a two-syllable, two-tonal howl, the human version of a loud call to communicate over long distances, we didn’t get a response. We concluded that no one was following this party and we headed to the original location to try to do a proper hand-over. We were lucky. The bonobos hadn’t moved much in the meantime and we quickly got a whoop response, so we easily found the morning team. We were not extremely lucky, though, as this party contained only an adult female, Suzy, with her dependent daughter Salea, and a juvenile male called Hugo. Hugo is eight years old, but is not much bigger than Salea who is four. Hugo was born in this group, but left the study area a couple of years ago together with three other individuals at a time when poachers were thought to be active around. However, two years after this sudden incident, Apollo, a subadult male among the four who disappeared, showed up again carrying his brother Hugo on his back. Hugo’s mother has never been seen, and Apollo took over the care of his younger brother. Because of his early orphaning, he always lagged behind in his development.
Three individuals are not always easy to follow, but as long as we could keep up with this small party, we would be fine. “Bonobos always lead you to more bonobos”, Sarah said. After a first bit of travel, Suzy went up an emergent tree. She was sitting on a huge branch and tried to grasp it steadily so she could reach something below on the main trunk of the tree. When Suzy was hanging there in this acrobatic position with her daughter watching interested nearby, I saw a lot of bees flying around. A minute later she was licking the honey of her hands, clearly a highly valued food source. Bonobos’ closest relatives, chimpanzees (Pan troglodytes), also eat honey and the ones at Goualougo in the Nouabale-Ndoki National Park in the Republic of Congo use a complex set of tool to access it (you can see exactly how in one of the BBC series). About an hour later Suzy stopped at a small termite mound repeatedly picking something from the top. It was difficult to determine whethershe was eating termites or pieces of soil. Bonobos are known to feed on termites, but not to the same amount and especially not in the same way as chimpanzees do. Chimpanzees are well-known termite fishers. They pick a small twig, strip off the leaves and insert it in a termite hole to lick off the termites attached to the twig. It is a big mystery why bonobos don’t use tools when compared to chimpanzees. One possible explanation is that bonobos live in an environment that is rich enough and doesn’t necessitate extractive foraging like tool-use.
Eventually we lost our small party of three when they travelled through thick vegetation on the ground. Because we knew Niina was still around doing a full-day follow, Sarah whooped to try to get in touch. We got a double whoop response back, meaning that Niina was with bonobos. We took a compass bearing and started walking towards the source of the double whoop. After a hundred meters we reached a very steep ravine about ten to fifteen meters deep with a little stream running below. When we finally managed to climb to the other side, using a fallen log as a bridge, we soon came across a second, even deeper, ravine. I always highly appreciate discovering such hidden treasures in the forest, but they greatly slow you down when you need to get somewhere quickly. When we eventually reached the main trail on the west side we didn’t get a response to our whoops. We started walking along another trail, hoping we were heading in the right direction. Some 500 meters further we finally caught up with Niina and the big party she was following, including Suzy, Salea and Hugo. The bonobos were travelling terrestrially eating the young shoots and pith of Haumania on their way. For those who are not familiar with Haumania, Wikipedia might tell you that it is considered as terrestrial herbaceous vegetation (THV). You are now probably thinking of a small, lovely herb on the forest floor, but herbaceous just means that this plant is not a tree and does not contain lignin. Haumania has long stems, some of which grow vertically, and often forms very dense tangles. Bonobos go for Haumania shoots, especially in the afternoon, probably for its high protein content. The group was travelling north and when we got to a dense Haumania patch we got separated from Niina. When we got to the other side we lost the bonobos out of sight and soon we were even out of whooping distance from Niina. Bonobos can be very hard to follow as they decide to head straight towards a certain spot at full speed. We caught up with Niina and the bonobos about half an hour later at their last feeding tree for the day. A couple of minutes after we arrived, individuals started to come down, travelling further northeast. It felt so amazing to see dozens of bonobos coming down to the ground, walking ten meters from you, totally ignoring you, doing their thing. We walked along with them, crossed a trail, which the bonobos decided to follow. At normal walking speed we were following behind some individuals, while the rest of the group was behind us on the trail. Finally the bonobos arrived at their sleeping site and started building their nests at 17:45. Our small party had joined the bigger one and travelled almost five kilometers since we first found them at noon. What a wonderful afternoon, what a pleasure to spend a couple of hours near these apes who totally accept our presence around. This motivated me to keep up our work on the east to one day get to the same level of habituation.