Abstract
Long-term demographic observations on a large-sized unit-group of chimpanzees in the Mahale Mountains, Tanzania, are summarized. The unit-group, the M group, contains over 100 individuals, which makes it the largest unit-group ever reported. The age-sex composition, natality, mortality and transfers of the M group are analyzed. An attempt is made to illustrate an age-sex pyramid of the group by estimating the ages of all the individuals in the group. The results reveal that: (1) the mortality rate of the male infants within 1 year almost doubled that of female infant; (2) adult male to adult female ratio of the M group is considerably higher than any other unit-groups elsewhere; and (3) the M group contains a relatively large number of old animals over 40 years of age, suggesting that the longevity of wild chimpanzees might be greater than estimated so far.
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References
Ghiglieri, M. P., 1984.The Chimpanzees of Kibale Forest. Columbia Univ. Press, New York.
Goodall, J. van Lawick, 1971.In the Shadow of Man. Collins, London.
, 1983. Population dynamics during a 15 year period in one community of free-living chimpanzees in the Gombe National Park, Tanzania.Z. Tierpsychol., 61: 1–60.
,A. Bandora, E. Bergmann, C. Busse, H. Matama, E. Mpongo, A. Pierce &D. Riss, 1979. Intercommunity interactions in the chimpanzee population of the Gombe National Park. In:The Great Apes,D. Hamburg &E. McCown (eds.), Benjamin & Cummings, Menlo Park, pp. 13–53.
Itani, J., &A. Suzuki, 1967. The social unit of chimpanzees.Primates, 8: 355–381.
Izawa, K., 1970. Unit groups of chimpanzees and their nomadism in the savanna woodland.Primates, 11: 1–46.
Kawanaka, K., 1981. Infanticide and cannibalism in chimpanzees, with special reference to the newly observed case in the Mahale Mountains.Afr. Stud. Monogr., 1: 69–99.
Kuroda, S., 1979. Grouping of pygmy chimpanzees.Primates, 20: 161–183.
Nishida, T., 1968. The social group of wild chimpanzees in the Mahali Mountains.Primates, 7: 141–204.
, 1977. Chimpanzees of the Mahale Mountains. (1) Ecology and social structure of the unitgroup. In:The Chimpanzee,J. Itani (ed.), Kodansha, Tokyo, pp. 543–633. (in Japanese)
, 1979. The social structure of chimpanzees of the Mahale Mountains. In:The Great Apes,D. Hamburg &E. McCown (eds.), Benjamin & Cummings, Menlo Park, pp. 73–121.
, 1983. Alpha status and agonistic alliance in wild chimpanzees (Pan troglodytes schweinfurthii).Primates, 24: 318–336.
&K. Kawanaka, 1972. Inter-unit-group relationships among wild chimpanzees of the Mahali Mountains.Kyoto Univ. Afr. Stud., 7: 131–169.
,M. Hiraiwa-Hasegawa, T. Hasegawa &Y. Takahata, 1985. Group extinction and female transfer in wild chimpanzees in the Mahale Mountain National Park, Tanzania.Z. Tierpsychol., 67: 284–301.
Pusey, A. E., 1979. Intercommunity transfer of chimpanzees in Gombe National Park. In:The Great Apes,D. Hamburg &E. McCown (eds.), Benjamin & Cummings, Menlo Park, pp. 465–479.
Sugiyama, Y., 1984. Population dynamics of wild chimpanzees at Bossou, Guinea, between 1976 and 1983.Primates, 25: 391–400.
Suzuki, A., 1971. Carnivority and cannibalism observed among forest-living chimpanzees.J. Anthropol. Soc. Nippon, 79: 30–48.
Teleki, G., E. E. Hunt, Jr. &J. H. Pfifferling, 1976. Demographic observations (1963–1973) on the chimpanzees of Gombe National Park, Tanzania.J. Human Evol., 5: 559–598.
Tutin, C. E. G., W. C. McGrew &P. J. Baldwin, 1983. Social organization of savanna-dwelling chimpanzees,Pan troglodytes verus, at Mt. Assirik, Senegal.Primates, 24: 154–173.
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Hiraiwa-Hasegawa, M., Hasegawa, T. & Nishida, T. Demographic study of a large-sized unit-group of chimpanzees in the mahale mountains, Tanzania: A preliminary report. Primates 25, 401–413 (1984). https://doi.org/10.1007/BF02381663
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DOI: https://doi.org/10.1007/BF02381663