, Volume 50, Issue 4, pp 293–303 | Cite as

Infanticide and social flexibility in the genus Gorilla

  • Juichi YamagiwaEmail author
  • John Kahekwa
  • Augustin Kanyunyi Basabose
Review Article Special contributions to commemorate the 60th anniversary of Japanese primatology


Based on the cases of infanticide by male mountain gorillas reported from the Virunga volcanic region, the socioecological and life history features of gorillas satisfy the conditions for which infanticide may be expected. However, there are considerable variations in the occurrence of infanticide between habitats. We analyze the recent reports of infanticides that were directly observed or are suspected based on field evidence in two populations of eastern and western lowland gorillas (Kahuzi and Mbeli Bai, respectively) along with previous reports on mountain gorillas, and consider which social features are linked with and which factors influence the occurrence of infanticide in the gorilla populations. All victims were suckling infants and most of them were killed by males who seemed unrelated to them. Dependent infants are most vulnerable to infanticide when the protector male (its putative father in most cases) is absent, and so male protection ability seems to be important in determining female transfer decisions. Two cases observed in Kahuzi suggest that the infanticidal male may discriminate between infants to accept and those to kill according to his previous interactions with their mothers. Mating for a prolonged period prior to parturition is necessary for immigrant females to avoid infanticide by the new male of the group that they join. Infanticide was usually associated with female transfer, and the patterns of female association at transfer may shape variations in social structure between populations. Female mountain gorillas prefer large groups with multiple males and tend to transfer alone in order to seek more protection against infanticide in Virunga. By contrast, female eastern and western lowland gorillas tend to transfer with other females to small groups or solitary males, and maturing silverbacks take females to establish new groups through group fission in Kahuzi and Mbeli Bai. These differences may result in more multi-male and larger groups in the Virungas than in Kahuzi and Mbeli Bai. Rapid changes in density of gorilla social units and their relations following drastic environmental changes caused by recent human disturbances may also increase the probability of infanticide.


Gorilla Infanticide Male reproductive tactics Multi-female transfer Social structure Environmental changes 



This study was financed in part by Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology, Japan (No. 162550080 and No. 19107007 to J. Yamagiwa), the Global Environmental Research Fund from the Japanese Ministry of the Environment (F-061 to T. Nishida, Japan Monkey Centre), and the Kyoto University Global COE Program “Formation of a Strategic Base for Biodiversity and Evolutionary Research.” It was conducted in cooperation with the Centre de Recherches en Sciences Naturelles, Democratic Republic of Congo. We thank the Institut Congolais pour Conservation de la Nature of the Congolese government for supporting our research project. We are also greatly indebted to all field assistants in Kahuzi-Biega National Park and the people living in the villages next to the parks for their kind support and hospitality throughout the fieldwork.


  1. Agoramoorthy G, Rudran R (1995) Infanticide by adult and subadult males in free-ranging red howler monkeys of Venezuela. Ethology 99:75–88Google Scholar
  2. Altmann J (1990) Primate males go where the females are. Anim Behav 39:193–195CrossRefGoogle Scholar
  3. Amsini F, Ilambu O, Liengola I, Kujirakwinja D, Hart J, Grossman F, Plumptre AJ (2008) The impact of civil war on the Kahuzi-Biega National Park: results of surveys between 2000–2008Google Scholar
  4. Borris C, Launhardt K, Epplen C, Epplen JT, Winkler P (1999) Males as infant protectors in Hanuman langurs (Presbytis entellus) living in multimale groups: defense pattern, paternity, and sexual behavior. Behav Ecol Sociobiol 46:350–356CrossRefGoogle Scholar
  5. Bradley Bj, Robbins MM, Williamson EA, Steklis DH, Steklis NG, Eckhardt N, Boesch C, Vigilant L (2005) Mountain gorilla tug-of-war: silverbacks have limited control over reproduction in multimale groups. Proc Natl Acad Sci USA 102:9418–9423PubMedCrossRefGoogle Scholar
  6. Busse CD, Gordon TP (1983) Attacks on neonates by a male mangabey (Cercocebus atys). Am J Primatol 6:133–141CrossRefGoogle Scholar
  7. Crockett CM, Sekulic R (1982) Gestation length in red howler monkeys. Am J Primatol 3:291–294CrossRefGoogle Scholar
  8. Doran DM, McNeilage A (2001) Subspecific variation in gorilla behavior: the influence of ecological and social factors. In: Robbins MM, Sicotte P, Stewart KJ (eds) Mountain gorillas: three decades of research at Karisoke. Cambridge University Press, London, pp 123–149Google Scholar
  9. Dunbar RIM (1988) Primate social system. Groom Helm, LondonGoogle Scholar
  10. Fairgrieve C (1995) Infanticide and infant eating in the blue monkey (Cercopithecus mitis stuhlmanni) in the Budongo Forest Reserve, Uganda. Folia Primatol 64:69–72PubMedCrossRefGoogle Scholar
  11. Fossey D (1982) Reproduction among free-living mountain gorillas. Am J Primatol 1:97–104CrossRefGoogle Scholar
  12. Fossey D (1983) Gorillas in the mist. Houghton Mifflin, BostonGoogle Scholar
  13. Fossey D (1984) Infanticide in mountain gorillas (Gorilla gorilla beringei) with comparative notes on chimpanzees. In: Hausfater G, Hrdy SB (eds) Infanticide: comparative and evolutionary perspectives. Aldine, Hawthorne, pp 217–236Google Scholar
  14. Goldsmith ML (1999) Ecological constraints on the foraging efforts of western gorillas (Gorilla gorilla gorilla) at Bai Hokou, Central African Republic. Int J Primatol 20:1–24CrossRefGoogle Scholar
  15. Hall JS (1994) Counting gorillas in Zaire’s Kahuzi-Biega NP. African Wildlife Update Nov–Dec:6Google Scholar
  16. Harcourt AH (1978) Strategies of emigration and transfer by primates, with particular reference to gorillas. Z Tierpsychol 48:401–420PubMedGoogle Scholar
  17. Harcourt AH, Greenberg J (2001) Do gorilla females join males to avoid infanticide? A quantitative model. Anim Behav 62:905–915CrossRefGoogle Scholar
  18. Harcourt AH, Stewart KJ (2007) Gorilla society: conflict, compromise and cooperation between the sexes. The University of Chicago Press, ChicagoGoogle Scholar
  19. Harcourt AH, Stewart KJ, Fossey D, Watts DP (1980) Reproduction in wild gorillas and some comparisons with chimpanzees. J Reprod Fert 28:59–70Google Scholar
  20. Harcourt AH, Stewart KJ, Fossey D (1981) Gorilla reproduction in the wild. In: Graham CE (ed) Reproductive biology of the great apes. Academic, New York, pp 265–279Google Scholar
  21. Hasegawa T (1989) Sexual behavior of immigrant and resident female chimpanzees at Mahale. In: Heltne PG, Marquardt LA (eds) Understanding chimpanzees. Harvard University Press, Cambridge, pp 90–103Google Scholar
  22. Hrdy SB (1979) Infanticide among mammals: a review, classification, and examination of the implications for the reproductive strategies of females. Ethol Sociobiol 1:13–40CrossRefGoogle Scholar
  23. Inogwabini B, Hall JS, Vedder A, Curran B, Yamagiwa J, Basabose K (2000) Status of large mammals in the mountain sector of Kahuzi-Biega National Park, Democratic Republic of Congo, in 1996. Afr J Ecol 38:269–276CrossRefGoogle Scholar
  24. Janson CH, Goldsmith ML (1995) Predicting group size in primates: foraging costs and predation risks. Behav Ecol 6:326–336CrossRefGoogle Scholar
  25. Janson CH, van Schaik CP (2000) The behavioral ecology of infanticide by males. In: van Schaik CP, Janson CH (eds) Infanticide by males and its implications. Cambridge University Press, Cambridge, pp 469–494Google Scholar
  26. Kalpers J, Williamson EA, Robbins MM, McNeilage A, Nzamurambaho A, Lola N, Mugiri G (2003) Gorillas in the crossfire: assessment of population dynamics of the Virunga mountain gorillas over the past three decades. Oryx 37:326–337CrossRefGoogle Scholar
  27. McNeilage A, Plumptre AJ, Brock-Doyle A, Vedder A (2001) Bwindi Impenetrable National Park, Uganda: Gorilla census 1997. Oryx 35:39–47Google Scholar
  28. Melanie ID, Gatti S, Levrero F, Duhamel G, Bermejo M, Vallet D, Menard N, Petit E (2007) Sex-biased dispersal in western lowland gorillas (Gorilla gorilla gorilla). Mol Ecol 16:2247–2259CrossRefGoogle Scholar
  29. Murnyak FD (1981) Censusing the gorillas in Kahuzi-Biega National Park. Biol Conserv 21:163–176CrossRefGoogle Scholar
  30. Nsubuga AM, Robbins MM, Boesch C, Vigilant L (2008) Patterns of paternity and group fission in wild multimale mountain gorilla groups. Am J Phys Anthropol 135:263–274PubMedCrossRefGoogle Scholar
  31. Nunn CL, van Schaik CP (2000) Social evolution in primates: the relative roles of ecology and intersexual conflict. In: van Schaik CP, Janson CH (eds) Infanticide by males and its implications. Cambridge University Press, Cambridge, pp 388–419Google Scholar
  32. Palombit RA (2003) Male infanticide in savanna baboons: adaptive significance and intraspecific variation. In: Jones CB (ed) Sexual selection and reproductive competition in primates: new perspectives and directions. American Society of Primatologists, Norman, pp 367–411Google Scholar
  33. Palombit RA, Cheney DL, Seyfarth RM (2001) Female-female competition for male “friends” in wild chacma baboons (Papio cynocephalus ursinus). Anim Behav 61:1159–1171CrossRefGoogle Scholar
  34. Parnell RJ (2002) Group size and structure in western lowland gorillas (Gorilla gorilla gorilla) at Mbeli Bai, Republic of Congo. Am J Primatol 56:193–206PubMedCrossRefGoogle Scholar
  35. Pope TR (1990) The reproductive consequences of male cooperation in the red howler monkey: paternity exclusion in multi-male and single-male troops using genetic markers. Behav Ecol Sociobiol 27:439–446CrossRefGoogle Scholar
  36. Robbins MM (2001) Variation in the social system of mountain gorillas: the male perspective. In: Robbins MM, Sicotte P, Stewart KJ (eds) Mountain gorillas: three decades of research at Karisoke. Cambridge University Press, Cambridge, pp 29–58Google Scholar
  37. Robbins MM (1995) A demographic analysis of male life history and social structure of mountain gorillas. Behaviour 132:21–47CrossRefGoogle Scholar
  38. Robbins MM (1999) Male mating patterns in wild multimale mountain gorilla groups. Anim Behav 57:1013–1020PubMedCrossRefGoogle Scholar
  39. Robbins MM (2003) Behavioral aspects of sexual selection in mountain gorillas. In: Jones CB (ed) Sexual selection and reproductive competition in primates: new perspectives and directions. American Society of Primatologists, Norman, pp 477–501Google Scholar
  40. Robbins AM, Robbins MM (2005) Fitness consequences of dispersal decisions for male mountain gorillas (Gorilla beringei beringei). Behav Ecol Sociobiol 58:295–309CrossRefGoogle Scholar
  41. Sato H, Yasui K, Byamana K, Mugunda B, Murhagane M (2000) Follow-up survey of environmental impacts of the Rwandan refugees on eastern D.R. Congo. Ambio 29(2):122–123Google Scholar
  42. Schaller GB (1963) The Mountain Gorilla: ecology and behavior. University of Chicago Press, ChicagoGoogle Scholar
  43. Sommer V (1994) Infanticide among the langurs of Jodhpur: testing the sexual selection hypothesis with a long-term record. In: Parmigiani S, vom Saal FS (eds) Infanticide and parental care. Harwood Academic Publishers, Chur, pp 155–198Google Scholar
  44. Steenbeek R (1999) Tenure related changes in wild Thomas’s langurs: I: between-group interactions. Behaviour 136:595–650CrossRefGoogle Scholar
  45. Stewart KJ (1988) Suckling and lactational anoestrus in wild gorillas (Gorilla gorilla). J Reprod Fert 83:627–634Google Scholar
  46. Stewart KJ, Sicotte P, Robbins MM (2001) Mountain gorillas of the Virungas: a short history. In: Robbins MM, Sicotte P, Stewart KJ (eds) Mountain gorillas: three decades of research at Karisoke. Cambridge University Press, London, pp 1–26Google Scholar
  47. Stokes EJ (2004) Within-group social relationships among females and adult males in wild western lowland gorillas (Gorilla gorilla gorilla). Am J Primatol 64:233–246PubMedCrossRefGoogle Scholar
  48. Stokes EJ, Parnell RJ, Olejniczak C (2003) Female dispersal and reproductive success in wild western lowland gorillas (Gorilla gorilla gorilla). Behav Ecol Sociobiol 54:329–339CrossRefGoogle Scholar
  49. Struhsaker TT, Leland L (1985) Infanticide in a patrilineal society of red colobus monkeys. Z Tierpsychol 69:89–132Google Scholar
  50. Tutin CEG (1996) Ranging and social structure of lowland gorillas in the Lopé Reserve, Gabon. In: McGrew WC, Marchant LF, Nishida T (eds) Great ape societies. Cambridge University Press, Cambridge, pp 58–70Google Scholar
  51. Van Noordwijk MA, van Schaik CP (2000) Reproductive patterns in eutherian mammals: adaptations against infanticide? In: van Schaik CP, Janson CH (eds) Infanticide by males and its implications. Cambridge University Press, Cambridge, pp 322–360Google Scholar
  52. van Schaik CP (2000a) Infanticide by male primates: the sexual selection hypothesis revisited. In: van Schaik CP, Janson CH (eds) Infanticide by males and its implications. Cambridge University Press, Cambridge, pp 27–60Google Scholar
  53. van Schaik CP (2000b) Social counterstrategies against infanticide by males in primates and other mammals. In: Kappeler PM (ed) Primate males. Cambridge University Press, Cambridge, pp 34–52Google Scholar
  54. Watts DP (1984) Composition and variability of mountain gorilla diets in the Central Virungas. Am J Primatol 7:323–356CrossRefGoogle Scholar
  55. Watts DP (1989) Infanticide in mountain gorillas: new cases and a reconsideration of the evidence. Ethology 81:1–18CrossRefGoogle Scholar
  56. Watts DP (1990) Mountain gorilla life histories, reproductive competition, and socio-sexual behavior and some implication for captive husbandry. Zoo Biol 9:185–200CrossRefGoogle Scholar
  57. Watts DP (1992) Social relationships of immigrant and resident female mountain gorillas. 1: male–female relationship. Am J Primatol 28:159–181Google Scholar
  58. Watts DP (1996) Comparative socio-ecology of gorillas. In: McGrew WC, Marchant LF, Nishida T (eds) Great ape societies. Cambridge University Press, Cambridge, pp 16–28Google Scholar
  59. Watts DP (1998) Long-term habitat use by mountain gorillas (Gorilla gorilla beringei). 1. Consistency, variation, and home range size and stability. Int J Primatol 19:651–680CrossRefGoogle Scholar
  60. Watts DP (2000) Causes and consequences of variation in male mountain gorilla life histories and group membership. In: Kappeler P (ed) Primate males. Cambridge University Press, Cambridge, pp 169–179Google Scholar
  61. Yamagiwa J (1983) Diachronic changes in two eastern lowland gorilla groups (Gorilla gorilla graueri) in the Mt. Kahuzi region, Zaire. Primates 24:174–183CrossRefGoogle Scholar
  62. Yamagiwa J (1986) Activity rhythm and ranging of a solitary male mountain gorilla (Gorilla gorilla beringei). Primates 27:273–282CrossRefGoogle Scholar
  63. Yamagiwa J (1987a) Male life history and the social structure of wild mountain gorillas (Gorilla gorilla beringei). In: Kawano S, Connell JH, Hidata T (eds) Evolution and coadaptation in biotic communities. University of Tokyo Press, Tokyo, pp 31–51Google Scholar
  64. Yamagiwa J (1987b) Intra- and inter-group interactions of an all-male group of Virunga mountain gorillas (Gorilla gorilla beringei). Primates 28:1–30CrossRefGoogle Scholar
  65. Yamagiwa J (1999) Socioecological factors influencing population structure of gorillas and chimpanzees. Primates 40:87–104CrossRefGoogle Scholar
  66. Yamagiwa J (2003) Bushmeat poaching and the conservation crisis in Kahuzi-Biega National Park, Democratic Republic of the Congo. In: Price SV (ed) War and tropical forests: conservation in areas of armed conflicts. Food Products Press, New York, pp 115–135Google Scholar
  67. Yamagiwa J, Basabose AK (2006) Effects of fruit scarcity on foraging strategies of sympatric gorillas and chimpanzees. In: Hohmann G, Robbins MM, Boesch C (eds) Feeding ecology in apes and other primates. Cambridge University Press, Cambridge, pp 73–96Google Scholar
  68. Yamagiwa J, Kahekwa J (2001) Dispersal patterns, group structure and reproductive parameters of eastern lowland gorillas at Kahuzi in the absence of infanticide. In: Robbins MM, Sicotte P, Stewart KJ (eds) Mountain gorillas: three decades of research at Karisoke. Cambridge University Press, London, pp 89–122Google Scholar
  69. Yamagiwa J, Kahekwa J (2004) First observations of infanticides by a silverback in Kahuzi-Biega. Gorilla J 29:6–9Google Scholar
  70. Yamagiwa J, Mwanza N, Spangenberg A, Maruhashi T, Yumoto T, Fischer A, Steinhauer BB (1993) A census of the eastern lowland gorillas Gorilla gorilla graueri in Kahuzi-Biega National Park with reference to mountain gorillas G. g. beringei in the Virunga region, Zaire. Biol Conserv 64:83–89CrossRefGoogle Scholar
  71. Yamagiwa J, Maruhashi T, Yumoto T, Mwanza N (1996) Dietary and ranging overlap in sympatric gorillas and chimpanzees in Kahuzi-Biega National Park, Zaire. In: McGrew WC, Marchant LF, Nishida T (eds) Great ape societies. Cambridge University Press, Cambridge, pp 82–98Google Scholar
  72. Yamagiwa J, Kahekwa J, Basabose AK (2003) Intra-specific variation in social organization of gorillas: implications for their social evolution. Primates 44:359–369PubMedCrossRefGoogle Scholar

Copyright information

© Japan Monkey Centre and Springer 2009

Authors and Affiliations

  • Juichi Yamagiwa
    • 1
    Email author
  • John Kahekwa
    • 2
  • Augustin Kanyunyi Basabose
    • 3
  1. 1.Laboratory of Human Evolution Studies, Graduate School of ScienceKyoto UniversitySakyoJapan
  2. 2.Parc National de Kahuzi-BiegaInstitut Congolais pour Conservation de la NatureBukavuDemocratic Republic of Congo
  3. 3.Centre de Recherche en Sciences Naturelles, LwiroD.S. BukavuDemocratic Republic of Congo

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