Responses of Chimpanzees to a Python
Great Ape Research Institute, Hayashibara Biochemical Laboratories, Inc., Japan
Chimpanzees in captivity have been known to show fear response to snakes1, and wild chimpanzees in Gombe, Tanzania, showed not only fear and avoidance responses (e.g., leaping back, moving away) but also aggressive behavior (e.g., hitting the snake, chasing and stamping on the ground, shaking saplings) toward live snakes (Causus rhombeatus, Philothamnus spp, etc.)2. Wild chimpanzees have also been known to express a “waa” bark2 and a “huu” (“hoo”) call2,3 when they saw snakes. However, few observations of the reactions of chimpanzees to snakes have been made in the wild.
African pythons (Python sabae) have been thought to be among the potential predators of juvenile and infant chimpanzees4. Only one case involving the reactions of wild chimpanzees to a half-dead python has been reported under experimental conditions in Gombe2. However, no reports on encounters between wild chimpanzees and wild pythons have been published. In this study, I will report on the response of wild chimpanzees to a live python.
I conducted field work from November to December 2008 in the Mahale Mountains National Park in Tanzania. I observed the members of M group5, which was consisted of 59 chimpanzees during the study period. I occasionally used a video camera (SONY, DCR-PC105) to record behavior.
I observed a party consisting of seven chimpanzees (two adult females: GW, RB; two adult males: AL, PM; two young females: PF, RC; and one infant: RB07) at 12:04 on December 15, 2008. At this time, they were resting in the forest near the Mpila River in the northern part of the home range of M group. At 12:07, I heard “wraa” calls from a few hundred meters east. RB then visually searched for the direction from which the “wraa” calls came and for the location of her offspring (RC and RB07); she alternated between these two search patterns. The “wraa” calls were uttered continuously by one chimpanzee. At 12:10, GW and her adopted offspring (PF) traveled eastward, and RB followed them with her offspring. The two adult males did not move immediately; however, 2 minutes later, PM (alpha male) also went eastward, and AL (beta male) and I followed him.
At 12:18, we arrived at a bush with thick woody vines and met another seven chimpanzees (three adult females: CA, FT, LD; two juvenile females: FV, CR; and two infants: FM, LD07). The party now consisted of 14 chimpanzees, but only one chimpanzee gave “wraa” calls. Eleven chimpanzees watched the bush from a distance of 3 meters. Four juveniles (CR, FV, PF, and RC) climbed a 2-meter-high woody vine, but the adults (AL, PM, and GW) and the mothers ventrally carrying infant offspring (LD and LD07, RB and RB07) sat on the ground. These observers waited and watched events occurring near the bush. At 12:22, AL shook a woody vine quietly and leaped back, but the others did not move and did not show surprise. Next, PM approached and sat on a woody vine about 1 meter from the bush and shook the vines both aggressively and gently.
At 12:25, PM stopped shaking the vines and sat on the ground; he glanced at the bush and leaped back when he noticed the head of python sticking out of the bush (Figure 1, Video 1: available online at mahale.main.jp/PAN/18_2/18(2)_01.html). The python lay motionless for several seconds but then started to come toward me. I moved away on my hands and knees, and 10 seconds later, I looked back and saw the python slithering on the ground about 5 meters away from me. The chimpanzees watched the python intently (Figure 2). We observed the python for about 1 minute until it hid in another bush. Twenty seconds later, PM tracked the python quietly on foot, but he stopped, turned to look at AL, and grimaced (Figure 3). AL immediately approached PM; RB, who was carrying her infant ventrally, and RC followed, and they all tracked the python (Figure 4). Two minutes later, GW, FV, and CA approached this group, which now surrounded the bush the python had entered. “Huu” calls were uttered by one or two chimpanzees during the 2 minutes after the python had appeared, but “wraa” calls were not heard.
Figure 1. A python sticking out of the bush.
Figure 2. PF watched the python intently from the woody vine.
Figure 3. PM grimaced tracking the python.
Figure 4. PM (left), AL, RB carrying her infant ventrally, and RC (right) tracked the python.
At 12:35, AL stopped waiting for the python and left; PM followed him. I heard pant-hoots from their direction, and these were met by pant-hoots uttered by many other members of M group, who were a few hundred meters from their location. Some of the females of the focal party remained near the bush for more than 30 minutes, but the python did not appear again. According to estimates based on the video recording, the python was about 2.8 meters long and 0.08 meter in maximum diameter, and moved at a speed of about 0.27 m/s (= 1.0 km/h).
Chimpanzees in Gombe showed fear and avoidance responses (rushing away, climbing trees) accompanied by loud “wraa” and soft “huu” calls when they detected a nearly dead python placed within the observation area2. Chimpanzees in Mahale also expressed “wraa” and “huu” calls, but after watching the python, only “huu” calls, which express puzzlement, surprise, or slight anxiety directed toward such phenomena as small snakes, rustling noises made by unidentified creatures, and so on6 were heard. Chimpanzees in Mahale also showed fear and avoidance responses (leaping back, climbing on vines, grimacing) to a python, but they were thought to be more interested in the python because they spent more time waiting, watching, and tracking it. Even a mother with her infant held ventrally and a juvenile followed the python despite its status as a potential predator of juvenile and infant chimpanzees4.
Many species of primates face a risk of predation from snakes. It has been hypothesized that the need to avoid snakes shaped the evolution of the primate visual system7. This hypothesis has been supported by experiments on Japanese monkeys (Macaca fuscata) reared with no experience with snakes who rapidly detected a picture of a snake8. Wild chimpanzees have been shown to detect and avoid pythons, but they also expressed interest in and approached these creatures. Although many researchers have studied chimpanzees in Mahale over the course 40 years, this is the only case of an encounter between chimpanzees and a python that has been reported. Because the chimpanzees of Mahale may not have been exactly sure about the nature of a python due to their lack of experience with this species, they may have been attracted to and puzzled by it.
I thank TAWIRI, TANAPA and COSTECH for permission to do the field research, and MMNP and MMWRC for logistic support. I also thank Mr. Hitonaru Nishie, Dr. Kazuhiko Hosaka, Dr. Akira Mori and Dr. Masami Hasegawa for valuable comments and Dr. Toshisada Nishida for his kind support. This study was financially supported by the Global Environment Research Fund of the Ministry of Environment, Japan (F-061 to T. Nishida).
Back to Contents