Population Estimates and Habitat Preferences of Orangutans Based on Line Transects of Nests

  • C. P. van Schaik
  • A. Priatna
  • D. Priatna


Effective conservation of a species requires accurate information on its geographic distribution and on its densities in the range of habitats it occupies, as well as estimates of its total numbers. For the orangutan, widely divergent estimates of total numbers have been produced over the years. In this study, we used line transects of nests to estimate population densities of Sumatran orangutans. The parameters needed for this technique were obtained from large nest samples by S. Djojosudharmo and T. Mitra Setia, and from field trials. The accuracy of the method could be validated at Ketambe, a site with known density. We found that orangutan densities are highest in forests on floodplains, that they strongly decline with altitude and that this decline is most plausibly ascribed to declines in the abundance of fruits with fleshy pulp. We note that densities in one site may vary due to movements between habitats. We also present preliminary evidence that floodplain forests may act as keystone habitats for orangutans living in the adjacent hills and thus, subsidize orangutan densities in adjacent uplands.


Line Transect Floodplain Forest Nest Density Fruit Abundance Line Transect Method 
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Copyright information

© Springer Science+Business Media New York 1995

Authors and Affiliations

  • C. P. van Schaik
    • 1
    • 2
  • A. Priatna
    • 3
    • 4
  • D. Priatna
    • 3
    • 4
  1. 1.Department of Biological Anthropology and Anatomy and Center for Tropical ConservationDuke UniversityDurhamUSA
  2. 2.New York Zoological Society - The Wildlife Conservation SocietyUSA
  3. 3.Universitas NasionalPasar Minggu, Jakarta SelatanIndonesia
  4. 4.Biological Sciences ClubPasar Minggu, Jakarta SelatanIndonesia

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