Abstract
In gorillas, the mother takes full responsibility for carrying and feeding offspring, and lactational amenorrhea prevents her from investing in another offspring while suckling. Therefore, mothers should encourage immature gorillas to become gradually more independent until they are physically able to acquire sufficient resources, travel independently, and manage social relationships unaided. We investigated the development of independence in a population of wild western gorillas (Gorilla gorilla gorilla) at Mbeli Bai, Nouabalé-Ndoki National Park, Republic of Congo. We observed the spatial proximity, the development of travel, patterns of suckling and weaning, and the nature of mother-offspring interactions for 42 immature gorillas to investigate the nature of the relationship between mother and offspring. Though mother-offspring distance and independent travel increased during immaturity, with few active interactions between the dyads, offspring still continued to suckle until a median age of 4.6 yr, longer than in mountain gorillas. The tolerance of the mother toward suckling by older offspring may reflect the importance of continued nutritional investment: the temporal nature of the diet of western gorillas means that succulent fruits—likely to be preferred weaning foods—are not always available. We propose that to buffer against potential fruit shortage, mothers continue to nurse their offspring to decrease the likelihood of death from care-dependent factors and to improve an offspring’s chances of survival.
Similar content being viewed by others
References
Altmann, J. (1974). Observational study of behaviour: Sampling methods. Behaviour, 49, 227–267.
Barrett, L., Henzi, S. P., Lycett, J. E. (2006). Whose life is it anyway? Maternal investment, developmental trajectories and life history strategies in baboons. In L. Swedell & S. R. Leigh (Eds.), Baboon Reproductive Strategies and Life History (pp. 199–224). London: Kluwer Academic Publishers.
Bateson, P. (1994). The dynamics of parent-offspring relationships in mammals. Trends in Ecology & Evolution, 9, 399–403.
Berman, C. M. (1988). Maternal condition and offspring sex ratio in a group of free ranging rhesus monkeys: An eleven year study. American Naturalist, 131, 307–328.
Bermejo, M. (2004). Home-range use and intergroup encounters in western gorillas (Gorilla g. gorilla) at Lossi Forest, North Congo. American Journal of Primatology, 64, 223–232.
Boesch, C. (1997). Evidence for dominant wild female chimpanzees investing more in sons. Animal Behaviour, 54, 811–815.
Boesch, C., & Boesch-Achermann, H. (2000). The Chimpanzees of the Taï Forest: Behavioural Ecology and Evolution. Oxford University Press, Oxford.
Brown, G. R., & Dixson, A. F. (2000). The development of behavioural sex differences in infant rhesus macaques (Macaca mulatta). Primates, 41, 63–77.
Byrne, R. W., & Byrne, J. M. E. (1993). The complex leaf gathering skills of mountain gorillas (Gorilla g. beringei)—variability and standardization. American Journal of Primatology, 31, 241–261.
Cipolletta, C. (2004). Effects of group dynamics and diet on the ranging patterns of a western gorilla group (Gorilla gorilla gorilla) at Bai Hokou, Central African Republic. American Journal of Primatology, 64, 193–205.
Clutton-Brock, T., Albon, S. D., & Guinness, F. E. (1984). Maternal dominance, breeding success, and birth sex ratios in red deer. Nature, 308, 358–360.
Delgado, R. A., & van Schaik, C. P. (2000). The behavioral ecology and conservation of the orangutan (Pongo pygmaeus): A tale of two islands. Evolutionary Anthropology, 9, 201–218.
Devinney, B. J., Berman, C. M., & Rasmussen, K. L. R. (2001). Changes in yearling rhesus monkeys’ relationships with their mothers after sibling birth. American Journal of Primatology, 54, 193–210.
Doran, D., Greer, D., Mongo, P., & Schwindt, D. (2004). Impact of ecological and social factors on ranging in western gorillas. American Journal of Primatology, 64, 207–222.
Doran, D., McNeilage, A., Greer, D., Mocian, C., Mehlman, P., & Shah, N. (2002). Western lowland gorilla diet and resource availability: New evidence, cross-site comparisons, and reflections on indirect sampling methods. American Journal of Primatology, 58, 91–116.
Doran-Sheehy, D. M., & Boesch, C. (2004). Behavioral ecology of western gorillas: New insights from the field. American Journal of Primatology, 64, 139–143.
Fairbanks, L. A. (1993). Juvenile vervet monkeys: Establishing relationships and practising skills for the future. In M. E. Pereira & L. A. Fairbanks (Eds.), Juvenile Primates: Life History, Development, and Behavior (pp. 211–227). New York: Oxford University Press.
Fletcher, A. W. (2001). Development of infant independence from the mother in wild mountain gorillas. In M. M. Robbins, P. Sicotte & K. J. Stewart (Eds.), Mountain Gorillas: Three Decades of Research at Karisoke (pp. 153–182). Cambridge: Cambridge University Press.
Fossey, D. (1979). Development of the mountain gorilla (Gorilla gorilla beringei): The first 36 months. In D. A. Hamburg & E. R. McCown (Eds.), The Great Apes (pp. 139–186). Menlo Park, CA: Benjamin/Cummings.
Fragaszy, D., & Bard, K. A. (1997). Comparison of development and life history in Pan and Cebus. International Journal of Primatology, 18, 683–701.
Galdikas, B. F. M., & Wood, J. W. (1990). Birth spacing patterns in humans and apes. American Journal of Physical Anthropology, 83, 185–191.
Harvey, P. H., & Clutton-Brock, T. H. (1985). Life history variation in primates. Evolution, 39, 559–581.
Hooley, J. M., & Simpson, M. J. A. (1981). A comparison of primiparous and multiparous mother-infant dyads in Macaca mulatta. Primates, 22, 379–392.
Horvat, J. R., & Kraemer, H. C. (1981). Infant socialization and maternal influence in chimpanzees. Folia Primatologica, 36, 99–110.
Janson, C. H., & van Schaik, C. P. (1993). Ecological risk aversion in juvenile primates: Slow and steady wins the race. In M. E. Pereira & L. A. Fairbanks, (Eds.), Juvenile Primates; Life History, Development and Behavior (pp. 62–73.). New York: Oxford University Press.
Kappeler, P. M., Pereira, M. E., & van Schaik, C. P. (2003). Primate life histories and socioecology. In P. M. Kappeler & M. E. Pereira (Eds.), Primate Life Histories and Socioecology (pp. 1–20). Chicago: University of Chicago Press.
Lee, P. C. (1996). The meanings of weaning: growth, lactation and life history. Evolutionary Anthropology, 5, 87–96.
Lee, P. C., & Moss, C. J. (1986). Early maternal investment in male and female African elephant calves. Behavioural Ecology and Sociobiology, 18, 353–361.
Lycett, J. E., Henzi, S. P., & Barrett, L. (1998). Maternal investment in mountain baboons and the hypothesis of reduced care. Behavioural Ecology and Sociobiology, 42, 49–56.
Maestripieri, D., & Carrol, K. A. (1998). Risk factors for infant abuse and neglect in group-living rhesus monkeys. Psychological Science, 9, 143–145.
Maestripieri, D., Ross, S. K., & Megna, N. L. (2002). Mother-infant interactions in western lowland gorillas (Gorilla gorilla gorilla): Spatial relationships, communication, and opportunities for social learning. Journal of Comparative Psychology, 116, 219–227.
Magliocca, F., & Gautier-Hion, A. (2002). Mineral content as a basis for food selection by western lowland gorillas in a forest clearing. American Journal of Primatology, 57, 67–77.
Manson, J. H. (1999). Infant handling in wild Cebus capuchinus: Testing bonds between females? Animal Behaviour, 57, 911–921.
Meikle, D. B., Tilford, B. L., & Vessey, S. H. (1984). Dominance rank, secondary sex ratio and reproduction in polygynous primates. American Naturalist, 124, 173–188.
Nakamichi, M., Silldor, A., Bringham, C., & Sexton, P. (2004). Baby-transfer and other interactions between its mother and grandmother in a captive social group of lowland gorillas. Primates, 45, 73–77.
Nash, L. T. (1978). The development of the mother-infant relationship in wild baboons (Papio anubis). Animal Behaviour, 26, 746–759.
Nevison, C. M., Rayment, F. D. G., & Simpson, M. J. A. (1996). Birth sex ratios and maternal social rank in a captive colony of rhesus monkeys (Macaca mulatta). American Journal of Primatology, 39, 123–138.
Nicolson, N. A. (1987). Infants, mother and other females. In B. B. Smuts, D. L. Cheney, R. M. Seyfarth, R. W. Wrangham & T. T. Struhsaker (Eds.), Primate Societies (pp. 330–342). Chicago: University of Chicago Press.
Nowell, A. A. (2005). Behavioural Development in Wild Western Lowland Gorillas (Gorilla gorilla gorilla). Ph.D. thesis, University of Liverpool.
Nowel, A. A., & Fletcher, A. W. (in press) The development of feeding behaviour in wild western lowland gorillas (Gorilla gorrilla gorilla).
Parnell, R. J. (2002). The Social Structure and Behaviour of Western Lowland Gorillas (Gorilla gorilla gorilla). at Mbeli Bai, Republic of Congo. Ph.D. thesis, University of Stirling.
Remis, M. J. (1997). Western lowland gorillas (Gorilla gorilla gorilla) as seasonal frugivores: Use of variable resources. American Journal of Primatology, 43, 87–109.
Remis, M. J. (2000). Initial studies on the contributions of body size and gastrointestinal passage rates to dietary flexibility among gorillas. American Journal of Physical Anthropology, 112, 171–180.
Robbins, M. M., Bermejo, M., Cipolletta, C., Magliocca, F., Parnell, R. J., & Stokes, E. J. (2004). Social structure and life-history patterns in western gorillas (Gorilla gorilla gorilla). American Journal of Primatology, 64, 145–159.
Rogers, M. E., Abernethy, K., Bermejo, M., Cipolletta, C., Doran, D., McFarland, K., Nishihara, T., Remis, M. J., & Tutin, C. E. G. (2004). Western gorilla diet: A synthesis from six sites. American Journal of Primatology, 64, 173–192.
Stanford, C. B., & Nkurunungi, J. B. (2003). Behavioral ecology of sympatric chimpanzees and gorillas in Bwindi Impenetrable National Park, Uganda: diet. International Journal of Primatology, 24, 901–918.
Stewart, K. J. (1981). Social Development of Wild Mountain Gorillas. Ph.D. thesis, University of Cambridge.
Stewart, K. J. (1988). Suckling and lactational anestrus in wild gorillas (Gorilla Gorilla). Journal of Reproduction and Fertility, 83, 627–634.
Stokes, E. J., Parnell, R. J., & Olejniczak, C. (2003). Female dispersal and reproductive success in western lowland gorillas (Gorilla gorilla gorilla). Behavioural Ecology and Sociobiology, 54, 329–339.
Taylor, A. B. (1997). Relative growth, ontogeny and sexual dimorphism in Gorilla (Gorilla gorilla gorilla and G. g. beringei): Evolutionary and ecological considerations. American Journal of Primatology, 43, 1–31.
Taylor, A. B. (2002). Masticatory form and function in the African apes. American Journal of Physical Anthropology, 117, 133–156.
Trillmich, F. (1990). The behavioural ecology of maternal effort in fur seals and sea lions. Behaviour, 114, 3–20.
Trivers, R. (1972). Parental investment and sexual selection. In B. Campbell (Ed.), Sexual Selection and the Descent of Man 1871–1971 (pp. 136–179). Chicago: Heinemann Educational Books.
Trivers, R. (1974). Parent-offspring conflict. American Zoologist, 14, 249–264.
Trivers. R., & Willard, D. (1973). Natural selection of parent ability to vary the sex ratio of offspring. Science, 179, 90–92.
Tutin, C. E. G. (1996). Ranging and social structure of lowland gorillas in the Lope Reserve, Gabon. In W. C. McGrew, L. C. Marchant & T. Nishida (Eds.), Great Ape Societies (pp. 58–70). Cambridge: Cambridge University Press.
Tutin, C. E. G., & Fernandez, M. (1991). Responses of wild chimpanzees and gorillas to the arrival of primatologists: Behaviour observed during habituation. In H. O. Box (Ed.), Primate Responses to Environmental Change (pp. 187–197). Cambridge: Chapman and Hall.
Uchida, A. (1998). Variation in tooth morphology of Gorilla gorilla. Journal of Human Evolution, 34, 55–70.
van Lawick-Goodall, J. (1971). Some aspects of mother-infant relationships in a group of wild chimpanzees. In H. R. Schaffer (Ed.), The Origins of Human Social Relations (pp. 115–128). London: Academic Press.
van Noordwijk, M. A., & van Schaik, C. P. (2005). Development of ecological competence in Sumatran orangutans. American Journal of Physical Anthropology, 127, 79–94.
Watts, D. P. (1984). Composition and variability of mountain gorilla diets in the Central Virungas. American Journal of Primatology, 7, 323–356.
Watts, D. P. (1985). Observations on the ontogeny of feeding behavior in mountain gorillas (Gorilla gorilla beringei). American Journal of Primatology, 8, 1–10.
Watts, D. P. (1991). Mountain gorilla reproduction and sexual behavior. American Journal of Primatology, 24, 211–225.
Watts, D. P. (1996). Comparative socio-ecology of gorillas. In: W. C. McGrew, L. C. Marchant, & T. Nishida (Eds.), Great Ape Societies (pp. 16–29). Cambridge: Cambridge University Press.
Watts, D. P. (1998). Seasonality in the ecology and life histories of mountain gorillas (Gorilla gorilla beringei). International Journal of Primatology, 19, 929–948.
Watts, D. P., & Pusey, A. E. (1993). Behavior of juvenile and adolescent great apes. In M. E. Pereira & L. A. Fairbanks (Eds.) Juvenile Primates; Life History, Development and Behavior (pp. 148–167). New York: Oxford University Press.
White, L. J. T., & Tutin, C. E. G. (2001). Why gorillas and chimpanzees react diffirently to logging: a cautionary tale from Gabon. In: W. Weber, L. J. T. White, A. Vedder, & L. Naugthon–Treves (Eds.),African Rainforest Ecology and Conservation: An Interdisciplinary Perspective (pp. 449–462). New Haven, CT: Yale University Press.
Wich, S. A., Utami-Atmoko, S. S., Setia, T. M., Rijksen, H. D., Schurmann, C., & van Schaik, C. (2004). Life history of wild Sumatran orangutans (Pongo abelii). Journal of Human Evolution, 47, 385–398.
Acknowledgments
We thank the Ministère de l’Economie Forestière of Congo-Brazzaville and the Wildlife Conservation Society for permission to work in the Nouabalé-Ndoki National Park. We thank all staff of the Nouabalé-Ndoki Project, particularly Thomas Breuer, Emma Stokes, Mark Gately, and Bryan Curran. A University of Chester Gladstone Fellowship provided funding for A. Nowell.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Nowell, A.A., Fletcher, A.W. Development of Independence from the Mother in Gorilla gorilla gorilla . Int J Primatol 28, 441–455 (2007). https://doi.org/10.1007/s10764-007-9128-6
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10764-007-9128-6