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Primates

, Volume 40, Issue 2, pp 365–381 | Cite as

Sociological and demographic characteristics of a recently found arsi gelada population in ethiopia

  • Akio Mori
  • Toshitaka Iwamoto
  • Umeyo Mori
  • Afework Bekele
Article

Abstract

A new population of gelada baboons isolated from other known gelada populations living on the opposite side of the Rift Valley was found in 1989 in the Arsi region of Ethiopia (Mori &Belay, 1990). Subsequent observations were conducted on the new gelada population in three study periods of 16 to 55 days over three consecutive years, 1994–1996. When we compare this population with other well studied northern populations, densities were lower, band size was smaller and the ratio of juveniles to adult females was lower. Based onOhsawa andDunbar's (1984) criteria these results suggest that this population exploits the harshest environment among known gelada populations. This may be due to the severe effect of the dry season at low altitude in the study site. Band size was small in the study site. Association rates of units were low, and each unit behaved more independently than those of northern populations. Age-sex composition of units changed drastically between consecutive study periods, indicating unstable unit structure. Moreover, there seems to be a tendency in this population whereby several adult males easily invade and are incorporated into a unit but the unit is expected to thereafter divide. The phenomenon can be explained by two factors: (1) Each unit fed rather independently in this area, where units fed intensively on both plateau and the slope of the cliff; and (2) Males may be incorporated in a unit for defense against leopards. As the units were vary small in size and unstable as compared with the Semien gelada units, the traditional concept of a stable gelada unit formed by blood related females, does not seem to fit this population.

Key Words

Gelada baboons Demography Population Social change 

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References

  1. Barton, A. R.;Byrne, R. W.;Whiten, A. 1993. Ecology, feeding competition and social structure in baboons.Behav. Ecol. Sociobiol., 33: 321–329.Google Scholar
  2. Belay, G.;Shotake, T. 1998. Blood protein variation of a new population of gelada baboon (Theropithecus gelada), in the southern rift valley, Arusi Region, Ethiopia.Primates, 39: 183–198.Google Scholar
  3. Byrne, R. W.;Whiten, A.;Henzi, S. P. 1987. One-male groups and intergroup interactions of mountain baboons.Int. J. Primatol., 8: 615–633.Google Scholar
  4. Crook, J. H. 1966. Gelada baboon herd structure and movement: a comparative report.Symp. Zool. Soc. Lond., 18: 237–258.Google Scholar
  5. Dunbar, R. I. M. 1979. Structure of gelada baboon reproductive units: I. Stability of social relationships.Behaviour, 69: 72–87.Google Scholar
  6. Dunbar, R. I. M. 1983. Structure of gelada baboon reproductive units: III. The male's relationship with his females.Anim. Behav., 31: 565–575.CrossRefGoogle Scholar
  7. Dunbar, R. I. M. 1992a. Time: a hidden constraint on the behavioural ecology of baboons.Behav. Ecol. Sociobiol., 31: 35–49.CrossRefGoogle Scholar
  8. Dunbar, R. I. M. 1992b. A model of the gelada socioecological system.Primates, 33: 69–83.CrossRefGoogle Scholar
  9. Dunbar, R. I. M.;Dunbar, E. P. 1975.Social Dynamics of Gelada Baboons. S. Karger, Basel.Google Scholar
  10. Iwamoto, T.;Mori, A.;Kawai, M.;Bekele, A. 1996. Anti-predatory behaviours of gelada baboons.Primates, 37: 389–397.CrossRefGoogle Scholar
  11. Kawai, M. (ed.). 1979.Contribution to Primatology, Vol. 16: Ecological and Sociological Studies of Gelada Baboons. S. Karger, Basel.Google Scholar
  12. Kawai, M.;Dunbar, R. I. M.;Ohsawa, H.;Mori, U. 1983. Social organization of gelada baboons: social units and definitions.Primates, 24: 13–24.CrossRefGoogle Scholar
  13. Mori, A.;Belay, G. 1990. The distribution of baboon species and a new population of gelada baboons along the Wabi-Shebeli river, Ethiopia.Primates, 31: 495–508.CrossRefGoogle Scholar
  14. Mori, A.;Iwamoto, T.;Bekele, A. 1997. A case of infanticide in a recently found gelada population in Arsi, Ethiopia. Primates, 38: 79–88.CrossRefGoogle Scholar
  15. Mori, U. 1978. Social structure and dynamics in gelada baboons (Theropithecus gelada). Paper prepared in advance for participants in “Baboon Field Research: Myths and Models,” June 25–July 4, 1978. Wenner-Gren Foundation for Anthropological Research.Google Scholar
  16. Mori, U. 1979a. Individual relationships within a unit. In:Ecological and Sociological Studies of Gelada Baboons,Kawai,M. (ed.), S. Karger, Basel, pp. 94–124.Google Scholar
  17. Mori, U. 1979b. Unit formation and the emergence of a new leader. In:Ecological and Sociological Studies of Gelada Baboons,Kawai,M. (ed.), S. Karger, Basel, pp. 156–182.Google Scholar
  18. Mori, U. 1990. Change of the leader male in gelada one male units. In:Societies Before Mankind, Kyoikusha, Tokyo, pp. 271–289. (in Japanese)Google Scholar
  19. Ohsawa, H. 1979a. Local gelada population and environment of the Gich area. In:Ecological and Sociological Studies of Gelada Baboons,Kawai,M. (ed.), S. Karger, Basel, pp. 4–45.Google Scholar
  20. Ohsawa, H. 1979b. Herd dynamics. In:Ecological and Sociological Studies of Gelada Baboons,Kawai,M. (ed.), S. Karger, Basel, pp. 47–80.Google Scholar
  21. Ohsawa, H.;Dunbar, R. I. M. 1984. Variations in the demographic structure and dynamics of gelada baboon populations.Behav. Ecol. Sociobiol., 15: 231–240.CrossRefGoogle Scholar

Copyright information

© Japan Monkey Centre 1999

Authors and Affiliations

  • Akio Mori
    • 1
  • Toshitaka Iwamoto
    • 2
  • Umeyo Mori
    • 3
  • Afework Bekele
    • 4
  1. 1.Primate Research InstituteKyoto UniversityAichiJapan
  2. 2.Faculty of EducationMiyazaki University, 1-1Miyazaki, MiyazakiJapan
  3. 3.Nagoya Bunri CollegeAichiJapan
  4. 4.Department of Biology, Science FacultyAddis Ababa UniversityAddis AbabaEthiopia

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