First Observed Case of Chimpanzee Predation on Yellow Baboons (Papio cynocephalus) at the Mahale Mts. National Park.
Michio Nakamura
Dept. of Zoology, Kyoto University

I am reporting the first case of predation by chimpanzees on yellow baboons (Papio cynocephalus) at Mahale. Other than chimpanzees there are six diurnal primate species (Papio cynocephalus, Cercopithecus aethiops, Cercopithecus ascanius, Cercopithecus mitis, Colobus badius, and Colobus angolensis) in Mahale(1). Colobus badius and the three Cercopithecus species often fall victim to chimpanzees (2, 3, 4, 5). Colobus angolensis live in only higher parts of the Mahale Mountains.
Although yellow baboons are commonly seen in the range of M group chimpanzees, they had never been observed to be hunted by chimpanzees.
In Gombe, which is about 50 km north of Mahale, there is a different species of baboons (Papio anubis), and they are sometimes preyed upon by chimpanzees (6, 7, 8). There are no reports of chimpanzee predation on any species of baboons from the other sites of chimpanzee research (see review in 7).

5th. Jan. 1997
I was following a large party (35 or 36 individuals) including the alpha male Kalunde and adult females near the lower reaches of Mpila valley which is in the northern part of the M group range. There was another small party of 5 to 6 young males nearby, which included the beta and the gamma males. The two parties were not close enough to mix, but they could hear each other quite clearly.

At 10:30 am I was following Kalunde's party when I heard the loud calls of baboons and chimpanzees (perhaps of the young male party). At the time, I had no idea that they were hunting baboons. I thought that they might be threatening each other over resources or something. I ran towards the calls and saw three adult male baboons rushing at me. They seemed to be so panicked that they didn't see me until they were 5m away, at which point they turned away into the bush. At this time the chimpanzees became quiet again somewhere in the bush. Kalunde's party had not shown up.

At 10:45 am, the party of young males became noisy again. However, I didn't see any chimpanzees or baboons. Suddenly Kalunde and some females appeared on the observation trail and then ran into the bush where the party of young male chimpanzees were shouting. I then saw female and young baboons climbing trees to get away from the chimpanzees. No adult male baboons were seen. The chimpanzees got excited and were shouting and barking. Now I knew that the chimpanzees were hunting for baboons. Some female chimpanzees climbed a tree near the trail trying to catch baby baboons from their mothers, but they failed to catch any.

At 10:50 am, more shouts came from ahead of me. It appeared that young chimpanzees were chasing baboons. Kalunde and the females headed in their direction.
When I arrived, Kalunde had the carcass of an infant or juvenile monkey in his mouth. Its head had been crashed, so it was not possible to tell from the body shape that it was a baboon carcass. But its whitish yellow body color could not be the color of red colobus or guenons. I arrived too late to tell whether Kalunde captured it by himself or snatched from somebody else.
The meat eating was nothing special compared to the usual eating of red colobus monkeys. However, I did not observe Kalunde sharing meat to anyone, despite the fact that an adult male and some adult females were begging for it.

Why hasn't baboon hunting been observed in Mahale before?
The basic difference between baboons in Gombe and Mahale is that those in Gombe are olive baboons (Papio anubis) while those in Mahale are yellow baboons (Papio cynocephalus). Regarding body size, you would think that yellow baboons are more likely to be the victims of the predation, as they are more slender and smaller than olive baboons. However, this is not the case. As Wrangham (9) has stated, the high rate of predation on baboons in the former period of Gombe research is probably because of the influence of artificial feeding. Baboons in Gombe became habituated by visiting the provisioning site frequently, which might have increased the opportunity for encounters between the two species. Though chimpanzees in Mahale were once habituated by provisioning, baboons were not habituated as provisioning took place in the forested area in which baboons were not ranging. Therefore provisioning did not facilitate unnatural encounters of two species.
Friendly interactions such as grooming and play between baboons and chimpanzees are also observed in Gombe, but the two species do not meet often in Mahale. When not following chimpanzees, I was able to see baboons quite often but when I was following chimpanzees, I saw baboons only a few times. Another occasion when I saw baboons while following chimpanzees, baboons were more than 50m away from the chimpanzees in an open space along a river. Moreover, though chimpanzees apparently showed no interest in baboons, the latter looked concerned about the former (however, it is possible that they were worried about human observers).It is likely that baboons regard chimpanzees as their potential predators and avoid contact with them. In the past, the ranging areas of baboons in Mahale were limited to the shore of lake Tanganyika (2); consequently they never came up to Kansyana camp. But recently they have visited Kansyana Camp frequently. It is possible that overlapping of ranging areas of baboons and chimpanzees inncreased the opportunity of encounters of the two species, and which may have changed their relationships.


  1. Nishida, T., 1990. A quarter century of research in the Mahale Mountains: An overview. In: The Chimpanzees of the Mahale Mountains. Sexual and Life History Strategies. T. Nishida (ed.), pp.133-148. University of Tokyo Press, Tokyo.
  2. Nishida, T., S. Uehara, and R. Nyundo, 1979. Predatory behavior among wild chimpanzees of the Mahale Mountains. Primates 20: 1-20.
  3. Kawanaka, K., 1982. Further studies on predation by chimpanzees of the Mahale Mountains. Primates 23: 364-384.
  4. Takahata, Y., T. Hasegawa, and T. Nishida, 1983. Chimpanzee predation in the Mahale Mountains from August 1979 to May 1982. Int. J. of Primatol. 5: 213-233.
  5. Uehara, S., et al., 1992. Characteristics of predation by the chimpanzees in the Mahale Mountains National Park, Tanzania. In: Topics in Primatology, vol. 1: Human Origins. T. Nishida, W. C. McGrew, P. Marler, M. Pickford, and F. B. M. de Waal (eds.), University of Tokyo Press, Tokyo.
  6. Teleki, G.,1973. The Predatory Behavior of Wild chimpanzees. Bucknell University Press, Lewisburg, Pennsylvania.
  7. Goodall, J., 1986. The Chimpanzees of Gombe. Belknap, Harvard Univ. Press, Cambridge, Massachusetts.
  8. Wrangham, R. W., and E. van Z. Bergmann-Riss, 1990. Rates of predation on mammals by Gombe chimpanzees, 1972-1975. Primates 31: 157-170.
  9. Wrangham, R. W., 1975. The behavioral ecology of chimpanzees in Gombe National Park, Tanzania. Ph. D. diss., Cambridge University.

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