, 40:383 | Cite as

Tree structure and sex differences in arboreality among western lowland gorillas (Gorilla gorilla gorilla) at Bai Hokou, Central African Republic

  • Melissa J. Remis


The aim of six months of research in 1995 on the gorillas (Gorilla gorilla gorilla) at Bai Hokou, Central African Republic, was to study the effects of tree structure, relative numbers of arboreal feeding sites, and sex differences in body size on arboreal foraging. The analysis presented here also documents inter-annual variation in fruit availability and climbing by silverback gorillas by comparing the 1995 results to those from earlier research, 1990–1992. This analysis suggests that female gorillas maintain similar levels of arboreality in fruit-rich and fruit-poor seasons and years, but silverbacks may be more terrestrial when fruit is scarce or difficult to access. Trees of different shapes present different numbers of feeding sites to bigger males and smaller females. Male climbing is affected by the availability of fruit, and small trees with narrow crowns that lend easy access to fruit from the core. This study suggests that the energetics of vertical climbing and biomechanical constraints imposed by small branch feeding sites in the periphery of trees may constrain the arboreal behavior of male gorillas. Fine-tuned comparisons of food availability, tree structure, and variation in social context of behavior across habitats, will assist efforts to understand differences in ecology among populations and species of African apes.

Key Words

Positional behavior Diet Sex differences Fruit availability 


  1. Cant, J. G. H. 1987. Effects of sexual dimorphism in body size on feeding postural behavior of Sumatran orangutans (Pongo pygmaeus).Amer. J. Phys. Anthropol., 74: 143–148.CrossRefGoogle Scholar
  2. Cant, J. G. H. 1992. Positional behavior and body size of arboreal primates: a theoretical framework for field studies and an illustration of its application.Amer. J. Phys. Anthropol., 88: 273–283.CrossRefGoogle Scholar
  3. Cartmill, M. 1974. Pads and claws in arboreal locomotion. In:Primate Locomotion,Jenkins,F. A.,Jr. (ed.), Academic Press, New York, pp. 45–83.Google Scholar
  4. Cartmill, M.;Milton, K. 1977. The lorisform wrist joint and evolution of “brachiating” adaptations in Hominoidea.Amer. J. Phys. Anthropol., 47: 249–272.CrossRefGoogle Scholar
  5. Chapman, C. A.;Chapman, L. J.;Wrangham, R.;Hunt, K.;Gardner, D. L. 1992. Estimators of fruit abundance of tropical trees.Biotropica, 24(4): 527–531.CrossRefGoogle Scholar
  6. Chapman, C. A.;White, F. J.;Wrangham, R. W. 1993. Defining subgroup size in fission-fusion societiesFolia Primatol., 61: 31–34.PubMedGoogle Scholar
  7. Demment, M. W. 1983. Feeding ecology and the evolution of body size of baboons.Afr. J. Ecol., 21: 219–233.Google Scholar
  8. Doran, D. M. 1993. Sex differences in adult chimpanzee positional behavior: influence of body size on locomotion and posture.Amer. J. Phys. Anthropol., 91: 99–115.CrossRefGoogle Scholar
  9. Doran, D. M. 1996. Comparative positional behavior of the African apes. In:Great Ape Societies,McGrew,W. C.;Marchant,L. F.;Nishida,T. (eds.), Cambridge Univ. Press, Cambridge, pp. 213–224.Google Scholar
  10. Doran, D. M. 1997. The influence of seasonality on activity patterns, feeding behavior, ranging and grouping patterns in Tai chimpanzees,Int. J. Primatol., 18: 183–206.CrossRefGoogle Scholar
  11. Doran, D. M.;Hunt, K. D. 1994. Comparative locomotor behavior of chimpanzees and bonobos: species and habitat differences. In:Chimpanzee Cultures,Wrangham,R. W.;McGrew,W. C.;de Waal,F. B. M.;Heltne,P. G. (eds.) Harvard Univ. Press, Cambridge, Massachusetts, pp. 93–108.Google Scholar
  12. Fleagle, J. 1976. Locomotion and posture of Malayan siamang: implications for Hominoid evolution.Folia Primatol., 26: 245–269.PubMedGoogle Scholar
  13. Fleagle, J. G.;Mittermeier, R. A. 1980. Locomotor behavior, body size and comparative ecology of 7 Surinam monkeys.Amer. J. Phys. Anthropol., 52: 301–314.CrossRefGoogle Scholar
  14. Galdikas, B. M. F.;Teleki, G. 1981. Variations in subsistence activities of female and male Pongids: new perspectives on origins of Hominid labor division.Cur. Anthropol., 22(3): 241–255.CrossRefGoogle Scholar
  15. Goldsmith, M. L. 1996. Ecological influences on the ranging and grouping behavior of western lowland gorillas at Bai Hokou, Central African Republic. Ph.D. diss. State Univ. of New York, Stony Brook, New York.Google Scholar
  16. Grand, T. I. 1972. A mechanical interpretation of terminal branch feeding.J. Mammalogy, 53 (1): 198–201.CrossRefGoogle Scholar
  17. Halle, F.;Oldeman, R. A. A.;Tomlinson, P. B. 1978.Tropical Trees and Forests: An Architectural Analysis. Springer-Verlag, Berlin.Google Scholar
  18. Horn, H. S. 1971.The Adaptive Geometry of Trees, Princeton Univ. Press, Princeton.Google Scholar
  19. Hunt, K. D. 1992. Social rank and body size as determinants of positional behavior inPan troglodytes.Primates, 33: 347–357.CrossRefGoogle Scholar
  20. Hunt, K. D. 1994. Body size effects on vertical climbing among chimpanzees.Int. J. Primatol., 14: 855–865.Google Scholar
  21. Jungers, W. L. (ed.), 1984. Body size and the scaling of limb proportions in primates. In:Size and Scaling in Primate Biology, Plenum, New York, pp. 345–381.Google Scholar
  22. Jungers, W. L.;Susman, R. L. 1984. Body size and skeletal allometry in African apes. In:The Pygmy Chimpanzee: Evolutionary Biology and Behavior, Susman, R. L. (ed.), Plenum Press, New York, pp. 131–178.Google Scholar
  23. Mendel, F. 1976. Postural and locomotor behavior ofAlouatta palliata on various substrates.Folia Primatol., 26: 36–53.PubMedCrossRefGoogle Scholar
  24. Napier, J. R.;Napier, P. H. 1985.The Natural History of the Primates. MIT Press, Cambridge, Massachusetts.Google Scholar
  25. Nishihara, T. 1995. Feeding ecology of western lowland gorillas in the Nouabale-Ndoki National Park, Congo,Primates, 36: 151–168.CrossRefGoogle Scholar
  26. Peters, R. H.;Cloutier, S.;Dube, D.;Evans, A.;Hastings, P.;Kaiser, H.;Kohn, D.;Sarwer-Foner, B. 1988. The allometry of the weight of fruit on trees and shrubs in Barbados.Oecologia, 74: 612–616.CrossRefGoogle Scholar
  27. Remis, M. J. 1994. Feeding ecology and positional behavior of lowland gorillas in the Central African Republic. Ph.D. thesis, Yale Univ., New Haven, Connecticut.Google Scholar
  28. Remis, M. J. 1995. The effects of body size and social context on the arboreal activities of lowland gorillas in the Central African Republic.Amer. J. Phys. Anthropol., 97: 413–433.CrossRefGoogle Scholar
  29. Remis, M. J. 1997a. The ranging and grouping patterns of a lowland gorilla group in the Central African Republic.Amer. J. Primatol., 43: 87–109.CrossRefGoogle Scholar
  30. Remis, M. J. 1997b. Gorillas as seasonal frugivores: resources that vary in time and space.Amer. J. Primatol., 43: 111–133.CrossRefGoogle Scholar
  31. Remis, M. J. 1998. The gorilla paradox: the effects of body size and habitat on the positional behavior of lowland and mountain gorillas. In:Primate Locomotion: Recent Advances,Strasser,E.;Fleagle,J.;Rosenberger,A.;McHenry,H. (eds.), Plenum Press, New York, pp. 95–106.Google Scholar
  32. Ripley, S. 1967. The leaping of langurs: a problem in the study of locomotor adaptation.Amer. J. Phys. Anthropol., 26: 149–170.CrossRefGoogle Scholar
  33. Ripley, S. 1976. Gray zones and gray langurs: Is the “Semi”—concept seminal?Yrbk. Phys. Anthropol., 20: 376–394.Google Scholar
  34. Sokal, R. R.;Rohlf, F. J. 1981.Biometry. W. H. Freeman, New York.Google Scholar
  35. Strier, K. B. 1989. Effects of patch size on feeding associations in Muriquis (Brachyteles arachnoides).Folia Primatol., 52: 70–77.PubMedGoogle Scholar
  36. Tutin, C. E. G.;Fernandez, M. 1993. Faecal analysis as a method of describing diets of apes: examples from sympatric gorillas and chimpanzees at Lopé, Gabon.Tropics, 2 (4): 189–198.CrossRefGoogle Scholar
  37. Tutin, C. E. G.;Fernandez, M.;Rogers, M. E.;Williamson, E. A.;McGrew, W. C. 1991. Foraging profiles of sympatric lowland gorillas and chimpanzees in the Lopé Reserve, Gabon: foraging strategies and the natural diet of monkeys, apes and humans.Philos. Trans. R. Soc. Lond. (Biol.), 334: 179–186.CrossRefGoogle Scholar
  38. Tutin, C. E. G.;Ham, R. M.;White, L. J. T.;Harrison, M. J. S. 1997. The primate community of the Lopé Reserve, Gabon: diets, responses to fruit scarcity and effects on biomass.Amer. J. Primatol., 42: 1–24.CrossRefGoogle Scholar
  39. Tuttle, R. H.;Watts, D. P. 1985. The positional behavior and adaptive compleces ofPan gorilla. In:Primate Morphophysiology, Locomotor Analyses and Human Bipedalism,Kondo,S. (ed.), Univ. of Tokyo Press, Tokyo, pp. 261–288.Google Scholar
  40. White, F. J.;Wrangham, R. W. 1988. Feeding competition and patch size in chimpanzee speciesPan paniscus andP. troglodytes.Behaviour, 104: 148–164.Google Scholar
  41. Willoughby, D. 1978.All About Gorillas, A. S. Barnes, New York.Google Scholar
  42. Wrangham, R. W.;Smuts, B. B. 1980. Sex differences in the behavioral ecology of chimpanzees in the Gombe National Park, Tanzania,J. Reprod. Fertil. (suppl.), 29: 13–31.Google Scholar
  43. Zihlman, A. L. 1997. Natural history of apes: life history features in females and males. In:The Evolving Female: A Life History Perspective,Morbeck,M. E.;Galloway,A.;Zihlman,A. L. (eds.), Princeton Univ. Press, Princeton, pp. 86–103.Google Scholar

Copyright information

© Japan Monkey Centre 1999

Authors and Affiliations

  • Melissa J. Remis
    • 1
  1. 1.Department of Sociology and AnthropologyPurdue UniversityWest LafayetteUSA

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