Density and population estimate of gibbons (Hylobates albibarbis) in the Sabangau catchment, Central Kalimantan, Indonesia


We demonstrate that although auditory sampling is a useful tool, this method alone will not provide a truly accurate indication of population size, density and distribution of gibbons in an area. If auditory sampling alone is employed, we show that data collection must take place over a sufficient period to account for variation in calling patterns across seasons. The population of Hylobates albibarbis in the Sabangau catchment, Central Kalimantan, Indonesia, was surveyed from July to December 2005 using methods established previously. In addition, auditory sampling was complemented by detailed behavioural data on six habituated groups within the study area. Here we compare results from this study to those of a 1-month study conducted in 2004. The total population of the Sabangau catchment is estimated to be about in the tens of thousands, though numbers, distribution and density for the different forest subtypes vary considerably. We propose that future density surveys of gibbons must include data from all forest subtypes where gibbons are found and that extrapolating from one forest subtype is likely to yield inaccurate density and population estimates. We also propose that auditory census be carried out by using at least three listening posts (LP) in order to increase the area sampled and the chances of hearing groups. Our results suggest that the Sabangau catchment contains one of the largest remaining contiguous populations of Bornean agile gibbon.

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We thank the management and staff of the Centre for International Cooperation in Management of Tropical Peatland (CIMTROP) and the University of Palangka Raya for permission to work at the LAHG and for logistical assistance throughout the course of this study. SMC thanks LIPI (Indonesian Institute of Sciences) for permission to conduct research in Indonesia. Special thanks to Laura L.B. Graham for her help in devising the Excel mapping programme. Thanks to the project behaviour team (Ari, Ciscoes, Iwan, Santi, Thomas, Twenti, Yudhi and Zery), Simon Husson and Helen Morrogh-Bernard, the OuTrop research team and volunteers for invaluable assistance with data collection. The authors thank Mark Harrison, Simon Husson, David J. Chivers, Warren Brockelman, Jatna Supriatna and an anonymous reviewer for comments on this manuscript. Funding was provided by Primate Conservation Inc, the Cambridge Philosophical Society and the Orang-utan Tropical Peatland Project (OuTrop).

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Correspondence to Susan M. Cheyne.

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Cheyne, S.M., Thompson, C.J.H., Phillips, A.C. et al. Density and population estimate of gibbons (Hylobates albibarbis) in the Sabangau catchment, Central Kalimantan, Indonesia. Primates 49, 50–56 (2008).

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  • Bornean agile gibbon
  • Population density
  • Quadrangulation sampling
  • Sabangau catchment
  • Peat-swamp forest