, Volume 28, Issue 1, pp 1–30 | Cite as

Intra- and inter-group interactions of an all-male group of virunga mountain gorillas (Gorilla gorilla beringei)

  • Juichi Yamagiwa


Six unrelated male gorillas formed an all-male group within the Virunga mountain gorilla population. Frequent homosexual interactions characterized the high cohesiveness of this group. Such homosexual behavior reduced the inter-individual distances and increased the social tension between the two silverbacks in the group. The silverbacks retained “ownership” of the homosexual partners, but competed and fought with each other violently when the partners avoided or ignored their courtship. Neither submissive nor reassurance behavior was noted between the silverbacks. Thus, their relationships may not be explained in terms of dominance and subordinancy. However, the loser-support and mediating behavior observed in the group prevented them from engaging in severe fights. Aggression was always directed from the elder and dominant males to the younger and subordinate males, while supporting interactions occurred in the opposite direction. The blackbacks frequently supported the subadult aggressees by attacking the silverbacks, and the younger males displayed mediating behavior in violent fights between the silverbacks. The group's ranging was influenced by encounters with neighboring social units. The members avoided contact with other units and shifted their range after several encounters. On the other hand, when and after a subadult male had immigrated into their group, they frequently encountered other units and did not move away from the encounter site. An all-male group may not be a favorable unit for females to transfer to, but may be profitable for maturing males to associate with. Its formation is probably related to recent social change in the Virunga gorilla population.

Key Words

Gorilla gorilla beringei All-male group Male immigration Homosexual behavior Loser-support 


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  1. Altmann, S. A. &J. Altmann, 1970.Baboon Ecology. Univ. of Chicago Press, Chicago.Google Scholar
  2. Bernstein, I. S., 1970. Primate status hierarchies. In:Primate Behavior: Developments in Field and Laboratory Research, Vol. 1,L. A. Rosenblum (ed.), Academic Press, New York, pp. 71–109.Google Scholar
  3. Bertrand, M., 1969.The Behavioural Repertoire of the Stumptail Macaque. Bibliotheca Primatologica Vol. 11, S. Karger, Basel.Google Scholar
  4. Boelkins, R. C. &R. P. Wilson, 1972. Intergroup social dynamics of the Cayo Santiago rhesus (Macaca mulatta) with special reference to changes in group membership by males.Primates, 13: 125–140.CrossRefGoogle Scholar
  5. Bourliere, F., M. Bertrand, &C. Hunkeler, 1970. The ecology and behavior of Lowe's guenon (Cercopithecus campbelli lowei) in the Ivory Coast. In:Old World Monkeys,J. R. Napier &P. H. Napier (eds.), Academic Press, New York, pp. 297–350.Google Scholar
  6. Caro, T. M., 1976. Observations on the ranging behaviour and daily activity of lone silverback mountain gorillas (Gorilla gorilla beringei).Anim. Behav., 24: 889–897.Google Scholar
  7. DeVore, I., 1965. Male dominance and mating behavior in baboons In:Sex and Behavior,F. Beach (ed.), Wiley, New York, pp. 266–289.Google Scholar
  8. De Waal, F. B. M., 1978. Exploitative and familiarity-dependent support strategies in a colony of semi-free living chimpanzees.Behaviour, 66: 268–312.Google Scholar
  9. ————,J. A. R. M. van Hooff, &W. J. Netto, 1976. An ethological analysis of types of agonistic interaction in a captive group of Java-monkeys (Macaca fascicularis).Primates, 17: 257–290.CrossRefGoogle Scholar
  10. Elliott, R. C., 1976. Observations on a small group of mountain gorillas (Gorilla gorilla beringei).Folia Primatol., 25: 12–24.PubMedGoogle Scholar
  11. Fossey, D., 1972. Vocalizations of the mountain groilla (Gorilla gorilla beringei).Anim. Behav., 20: 36–53.Google Scholar
  12. ————, 1974. Observations on the home range of one group of mountain gorillas (Gorilla gorilla beringei).Anim. Behav., 22: 568–581.CrossRefGoogle Scholar
  13. ————, 1979. Development of the mountain gorilla (Gorilla gorilla beringei) through the first 36 months. In:The Great Apes,D. A. Hamburg &E. R. McCown (eds.), Benjamin/Cummings, Menlo Park, Calif., pp. 139–186.Google Scholar
  14. ————, 1981. The imperiled mountain gorilla.Nat. Geogr., 159: 501–523.Google Scholar
  15. ————, 1982. Reproduction among free-living mountain gorillas.Amer. J. Primatol. Suppl., 1: 97–104.Google Scholar
  16. ————, 1983.Gorillas in the Mist. Houghton Miffilin Co., Boston.Google Scholar
  17. ———— &A. H. Harcourt, 1977. Feeding ecology of free-ranging mountain gorilla (Gorilla gorilla beringei). In:Primate Ecology: Studies of Feeding and Ranging Behaviour in Lemurs, Monkeys and Apes,T. H. Clutton-Brock (ed.), Academic Press, London, pp. 415–447.Google Scholar
  18. Gartlan, J. S. &S. C. Gartlan, 1973. Quelques observations sur les groupes exclusivement males chezErythrocebus patas.Ann. Fac. Sci. Cameroun, 12: 121–144.Google Scholar
  19. Goodall, J., 1975. Chimpanzees of the Gombe Stream Reserve. In:Primate Behavior,I. DeVore (ed.), Holt, Rinehart, & Winston, New York, pp. 425–473.Google Scholar
  20. ————, 1968. The behaviour of free-living chimpanzees in the Gombe Stream Reserve.Anim. Behav. Monogr., 1(3): 161–311.Google Scholar
  21. ————, 1971.In the Shadow of Man. Houghton Mifflin Co., Boston.Google Scholar
  22. Gordon, T. P. &I. S. Bernstein, 1973. Seasonal variation in sexual behavior of all-male rhesus troops.Amer. J. Phys. Anthropol., 38: 221–225.Google Scholar
  23. Handler, N. T., R. K. Malenky, &N. Badrian, 1984. Sexual behavior ofPan paniscus under natural conditions in the Lomako forest, Equateur, Zaïre. In:The Pygmy Chimpanzee: Evolutionary Biology and Behavior,R. L. Susman (ed.), Plenum Press, New York & London, pp. 347–368.Google Scholar
  24. Harcourt, A. H., 1978a. Activity periods and patterns of social interaction: a neglected problem.Behaviour, 66: 121–135.Google Scholar
  25. ————, 1978b. Strategies of emigration and transfer by primates, with particular reference to gorillas.Z. Tierpsychol., 48: 401–420.PubMedGoogle Scholar
  26. ————, 1979. Social relationships among adult female mountain gorillas.Anim. Behav., 27: 251–264.Google Scholar
  27. ————, 1981. Intermale competition and the reproductive behavior of the great apes. In:Reproductive Biology of the Great Apes,E. E. Graham (ed.), Academic Press, New York, pp. 301–318.Google Scholar
  28. ————,K. J. Stewart, &D. Fossey, 1976. Male emigration and female transfer in wild mountain gorilla.Nature, 263: 226–227.CrossRefGoogle Scholar
  29. ————, & ————, 1981. Gorilla reproduction in the wild. In:Reproductive Biology of the Great Apes,E. E. Graham (ed.), Academic Press, New York, pp. 265–279.Google Scholar
  30. Hess, J. P., 1973. Some observations on the sexual behaviour of captive lowland gorillas,Gorilla g. gorilla (Savage andWyman). In:Comparative Ecology and Behaviour of Primates,R. P. Michael &J. H. Crook (eds.), Academic Press, London, pp. 507–581.Google Scholar
  31. Hrdy, S. B., 1974. Male-male competition and infanticide among the langurs (Presbytis entellus) of Abu Rajasthan.Folia Primatol., 22: 19–58.PubMedGoogle Scholar
  32. Itani, J., 1977. Evolution of primate social structure.J. Human Evol., 6: 235–243.Google Scholar
  33. ————, 1980. Social structure of African great apes.J. Reprod. Fertil. Suppl., 28: 33–41.PubMedGoogle Scholar
  34. ———— &K. Tokuda, 1958. The monkeys of Koshima islet.Nihondobutsuki, Vol. 3,K. Imanishi (ed.), Kobunsha, Tokyo. (in Japanese)Google Scholar
  35. Jay, P., 1965. The common langur of north India. In:Primate Behavior: Field Studies of Monkeys and Apes.I. DeVore (ed.), Holt, Rinehart, & Winston, New York, pp. 197–249.Google Scholar
  36. Kano, T., 1980. Social behavior of wild pygmy chimpanzees (Pan paniscus) of Wamba: A preliminary report.J. Human Evol., 9: 243–260.Google Scholar
  37. Kaplan, J., 1977. Patterns of fight interference in free-ranging rhesus monkeys.Amer. J. Phys. Anthropol., 47: 279–288.Google Scholar
  38. Kaufmann, J. H., 1965. A three-year study of mating behavior in a free-ranging band of rhesus monkeys.Ecology, 46: 500–512.Google Scholar
  39. Kummer, H., 1968.Social Organization of Hamadryas Baboons. Univ. of Chicago Press, Chicago.Google Scholar
  40. Kurland, J. A., 1977.Kin Selection in the Japanese Monkey. Contributions to Primatology, Vol. 12, S. Karger, Basel.Google Scholar
  41. Kuroda, S., 1980. Social behavior of the pygmy chimpanzee.Primates, 21: 181–197.Google Scholar
  42. Morgan, B. J. T., M. J. A. Simpson, J. P. Hanby, &J. Hall-Craggs, 1976. Visualizing interaction and sequential data in animal behavior: Theory and application of cluster-analysis methods.Behaviour, 59: 1–43.Google Scholar
  43. Mori, U., 1979. Development and sociability and social status. In:Ecological and Sociological Studies of Gelada Baboons,M. Kawai (ed.), Kodansha-Karger, Tokyo, pp. 4–45.Google Scholar
  44. Nadler, R. D., 1986. Sex-related behavior of immature wild mountain gorillas.Develop. Psychobiol. 19(2): 125–137.CrossRefGoogle Scholar
  45. Nishida, T., 1970. Social behavior and relationship among wild chimpanzees of the Mahali mountains.Primates, 11: 47–87.CrossRefGoogle Scholar
  46. ————, 1983. Alpha status and agonistic alliance in wild chimpanzees (Pan troglodytes schweinfurthii).Primates, 24: 318–336.Google Scholar
  47. Norikoshi, K. &N. Koyama, 1975. Group shifting and social organization among Japanese macaques. In:Proceedings from the Symposia of the Fifth Congress of the International Primatological Society,S. Kondo,M. Kawai,A. Ehara, &S. Kawamura (eds.), S. Karger, Basel, pp. 43–62.Google Scholar
  48. Packer, C., 1977. Reciprocal altruism inPapio anubis.Nature, 265: 441–443.CrossRefGoogle Scholar
  49. Riss, D. &J. Goodall, 1977. The recent rise to the alpha-rank in a population of free-living chimpanzees.Folia Primatol., 27: 134–151.PubMedGoogle Scholar
  50. Rowell, T. E., 1966. Hierarchy in the organization of a captive baboon group.Anim. Behav., 14: 430–443.PubMedGoogle Scholar
  51. Schaller, G. B., 1963.The Mountain Gorilla: Ecology and Behavior. Univ. of Chicago Press, Chicago.Google Scholar
  52. Seyfarth, R. M., 1976. Social relationships among adult female baboons.Anim. Behav., 24: 917–938.Google Scholar
  53. Simonds, P. E., 1965. The bonnet macaque in south India. In:Primate Behavior: Field Studies of Monkeys and Apes,I. DeVore (ed.), Holt, Rinehart, & Winston, New York, pp. 175–196.Google Scholar
  54. Struhsaker, T. T., 1967. Social structure among vervet monkeys (Cercopithecus aethiops).Behaviour, 29: 83–121.Google Scholar
  55. Vandenbergh, J. G., 1973. Environmental influences on breeding in rhesus monkeys. In:Primate Reproductive Behavior (Symp. 4th Int. Congr. Primatol.),C. H. Phoenix (ed.), S. Karger, Basel, pp. 1–19.Google Scholar
  56. Vedder, A., 1984. Movement patterns of a group of free-ranging mountain gorillas (Gorilla gorilla beringei) and their relation to food availability.Amer. J. Primatol., 7: 73–88.Google Scholar
  57. Watanabe, K., 1979. Alliance formation in a free-ranging troop of Japanese macaques.Primates, 20: 459–474.CrossRefGoogle Scholar
  58. Watts, D. P., 1984. Composition and variability of mountain gorilla diets in the central Virungas.Amer. J. Primatol., 7: 323–356.Google Scholar
  59. Yamagiwa, J., 1983. Diachronic changes in two eastern lowland gorilla groups (Gorilla gorilla graueri) in the Mt. Kahuzi region, Zaïre.Primates, 24: 174–183.Google Scholar
  60. ————, 1986. Activity rhythm and the ranging of a solitary male mountain gorilla (Gorilla gorilla beringei).Primates, 27: 273–282.CrossRefGoogle Scholar

Copyright information

© Japan Monkey Centre 1987

Authors and Affiliations

  • Juichi Yamagiwa
    • 1
  1. 1.Japan Monkey CentreInuyama, AichiJapan

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