, Volume 20, Issue 3, pp 323–339 | Cite as

Social structure and dynamics of wild chimpanzees at Bossou, Guinea

  • Yukimaru Sugiyama
  • Jeremy Koman


A small population of wild chimpanzees was studied at Bossou, Guinea, for six months from November 1976 to May 1977. All the chimpanzees except dependent infants were identified without artificial feeding and were observed from within 20 m almost every day. The population size of 21 chimpanzees was little changed from 1967. Although the sex ratio (male/female) of immatures (infants, juveniles, and adolescents) was 0.833 in January 1977, the adult sex ratio was 0.429. More than half of the males must therefore have disappeared. No desertion of males from the Bossou group was confirmed during the study period but two emigrated males from other groups did come to join the Bossou group for a short period.

Four out of six mothers had two or three children. From the age discrepancy of brothers/sisters, the mean birth interval from a mother was estimated to be about four years. An elder sister of two infants who had an age-gap of only three years, or perhaps less, disappeared without receiving sufficient care from her mother.

Mothers who had infants aged about 1 year or more showed swelling of their sexual skin and were confirmed to mate with males.


Population Size Social Structure Small Population Animal Ecology Birth Interval 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. Albrecht, H. &S. C. Dunnet, 1971.Chimpanzees in Western Africa. Piper, München.Google Scholar
  2. Goodall, J., 1965. Chimpanzees of the Gombe Stream Reserve. In:Primate Behavior,I. DeVore (ed.), Holt Rinehart, & Winston, N. Y., pp. 425–473.Google Scholar
  3. Hanby, J., 1976. Sociosexual development in primates. In:Perspectives in Ethology, Vol. 2,P. G. Bateson &P. H. Klopfer (eds.), Plenum Press, N. Y., pp. 1–67.Google Scholar
  4. Itani, J., 1972.Social Structure of Primates. Kyoritsu-Shuppan, Tokyo. (in Japanese)Google Scholar
  5. Kawanaka, K. &T. Nishida, 1975. Recent advances in the study of inter-unit-group relationships and social structure of wild chimpanzees of the Mahali Mountains. In:Proc. Symp. Vth Congr. Intern. Primat. Soc.,S. Kondo,M. Kawai,S. Kawamura, &A. Ehara (eds.), Japan Science Press, Tokyo, pp. 173–186.Google Scholar
  6. Kortlandt, A., 1962. Chimpanzees in the wild.Sci. Amer., 206(5): 128–138.PubMedGoogle Scholar
  7. Lawick-Goodall, J. van, 1968. The behaviour of free-living chimpanzees in the Gombe Stream Reserve.Anim. Behav. Monogr., 1(3): 161–311.Google Scholar
  8. Napier, J. R. &P. H. Napier, 1967.A Handbook of Living Primates. Academic Press, London.Google Scholar
  9. Nishida, T., 1968. The social group of wild chimpanzees in the Mahali Mountains.Primates, 9: 167–224.CrossRefGoogle Scholar
  10. ————, 1977. Social structure of chimpanzees. In:Anthropology Series, Vol. 2, Primates,J. Itani (ed.), Yuzankaku, Tokyo, pp. 277–314. (in Japanese)Google Scholar
  11. ————, 1972. Inter-unit-group relationships among wild chimpanzees of the Mahali Mountains.Kyoto Univ. African Stud., 7: 131–169.Google Scholar
  12. Reynolds, V., 1966. Open groups in hominid evolution.Man (N. S.) 1(4): 441–452.Google Scholar
  13. ————, 1965. Chimpanzees of the Budongo Forest. In:Primate Behavior,I. DeVore (ed.), Holt, Rinehart, & Winston, N. Y., pp. 368–424.Google Scholar
  14. Sugiyama, Y., 1968. Social organization of chimpanzees in the Budongo Forest, Uganda.Primates, 9: 225–258.CrossRefGoogle Scholar
  15. ————, 1973. The social structure of wild chimpanzees—A review of field studies. In:Comparative Ecology and Behaviour of Primates,R. P. Michael &J. H. Crook (eds.), Academic Press, London, pp. 375–410.Google Scholar
  16. ————, 1976. Life history of male Japanese monkeys. In:Advances in the Study of Behaviour, Vol. 7,J. S. Rosenblatt &R. Hinde (eds.), Academic Press, London, pp. 255–284.Google Scholar
  17. ————, 1978.Peoples and Chimpanzees of Bossou. Kinokuniya Shoten, Tokyo. (in Japanese)Google Scholar
  18. ----, (in press)Life Science Series, Vol. 15: Behaviour. Kyoritsu-Shuppan, Tokyo. (in Japanese)Google Scholar
  19. Suzuki, A., 1971. Carnivority and cannibalism observed among forest living chimpanzees.J. Anthrop. Soc. Nippon, 79: 30–48.Google Scholar

Copyright information

© Japan Monkey Centre 1979

Authors and Affiliations

  • Yukimaru Sugiyama
    • 1
  • Jeremy Koman
    • 2
  1. 1.Primate Research InstituteKyoto UniversityInuyama, AichiJapan
  2. 2.Laboratoire Mont NimbaLolaRépublique de Guinée

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