The mysterious kelo monkey

As the end of my stay at LuiKotale is approaching, I started focusing on a couple of side projects. One of these concerns kelo, the local name of one of the monkeys. I always like getting to know the local names of animals and plants. Nkolongo is the red colobus (Piliocolobus tholloni), nge the wolf’s guenon (Cercopithecus wolfi), ngila the black mangabey (Lophocebus aterrimus) and so on. Some of these names are similar to the ones I learned at Bolobo. When I was at Bolobo, I compiled a list of local names of animals known to the people in the region. From these interviews with villagers I learned to be skeptical at times, as the people in Central Africa are not used to recognize species from drawings in a book. I always try to get additional clues about the behaviour, habitat or calls of a species.

About 10 years ago a short communication was published in a scientific journal stating that the southern talapoin (Miopithecus talapoin) occurs around Mimia. The author found a freshly killed animal that got trapped in a cable snare by accident. The local name of this monkey was kelo, noted the author. I have always been interested in primate taxonomy and distribution, so this paper drew my attention right away. Mimia is approximately 100 km north of the Kasai River, the former limit of the southern talapoin. With the exception of the observation at Mimia, no records or populations of talapoins are known to science north of the Kasai. Mimia is about fifty kilometers from Lompole, the village that agreed to work together with the LuiKotale Bonobo Project, so since my arrival I kept this mysterious kelo monkey at the back of my mind.

In November I brought several cards with drawings of monkeys. A common technique to assess the reliability of the interviewee is to include species that do not occur in the area at all. As expected it proved difficult for most of the trackers to recognize monkeys from these drawings, but I had anticipated this, so I also brought pictures. Talapoins are ecologically very similar to the Allen’s swamp monkey (Allenopithecus nigroviridis). Both species live in swamps along big rivers and have a similar diet including a lot of invertebrates. Swamp monkeys and talapoins have been considered as each others ecological equivalents, which makes the possible occurrence of talapoins near Mimia extra exceptional. When I asked the trackers about the monkeys they know, specifically about the kelo, they all told me kelo monkeys occur along big rivers like the Lokoro north of camp. However, the local people don’t hunt these monkeys, so they were not really able to recognize my pictures. Talapoins are the smallest monkeys in Africa (a bit bigger than squirrel monkeys, Saimiri sp.), so I asked the trackers to show me the size of the kelo monkey. They hold there hands about twenty centimeters apart. And how do the calls sound like? High chirps like keskes, the red-tailed guenon (Cercopithecus ascanius whitesidei). This all fits with the hypothesis of the kelo being a talapoin. It got really exciting when the trackers told me stories about kelo monkeys stealing manioc tubers from ponds near the river, as this behaviour is specifically mentioned for talapoins in a French book on the natural history of Central African primates. However, as a good scientist I tried to remain skeptical and consider alternative hypotheses. People might have confused another monkey for a talapoin, leaving the kelo simply as the swamp monkey. Or most spectacular, both species might occur in the region (but maybe not in the same habitat) and the local people might refer to both species as kelo.

Over the months I tried to gather more information about the kelo monkey. I asked a friend to send in pictures of swamp monkeys, as well as the calls of both talapoin and swamp monkeys. Unfortunately, the trackers in camp didn’t know the calls of both species good enough to be conclusive. When I asked more about the size of the monkey, it turned out that the twenty centimeters they referred to, indicates the width of the animal. Apparently that’s what matters to hunters and therefore that’s how they talk about the size of an animal. I realized I would have to look for kelo monkeys myself to get absolute evidence.

The plan was to put out some camera traps as the water level drops in the dry season. About a month ago we went to Boele, one of the nearby fishing villages thirty minutes downstream along the Lokoro (so an hour to peddle back up), to ask the local fishermen for a good spot. Again these men didn’t know much about kelo monkeys. They remembered two cases of a kelo monkey being brought to the village. It shows how little these monkeys are being caught. In the end it turned out that Divano, our cook in camp, knew most about the kelo. He was imitating the call of a swamp before I even played it to him. It turned less and less likely that the kelo monkey was actually a talapoin, but the possibility remained. We set out two camera traps along the river and on the way back we found relatively fresh pooh on a leaf hanging over the river. I put it in ethanol. Who knows when this sample may become useful. A week later we returned in the early morning to check the camera traps. In the meantime the camp fisherman had seen kelo monkeys near the spot of one of the camera traps and he brought back some more pooh samples, so it was promising. When peddling down the misty river, I heard the alarm calls of a monkey I didn’t recognize. We saw some monkeys along a dried-up river bank. I saw one monkey briefly through my binoculars. It looked like a male swamp monkey, definitely not the size of the smallest monkey in Africa, but observation conditions were not good enough to be 100% certain. The monkeys left within seconds, but on the muddy river bank we found footprints and digging traces. We changed the camera trap to this spot and another week later the fisherman brought back the camera trap, because the water level was rising again. I immediately put the memory card in a laptop and yes!, on three videos a male swamp monkey can be seen searching for something edible in the mud. So what do we know so far: that swamp monkeys definitely occur along the Lokoro. Next step would be to go to Mimia to look for kelo monkeys there. But first I am planning to go a couple of more times on the river to see the swamp monkeys again and hopefully get some good pictures or footage. I will keep you updated on the mysterious kelo monkey along the Lokoro River.

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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.