, Volume 53, Issue 2, pp 181–192 | Cite as

Factors affecting reproduction in rehabilitant female orangutans: young age at first birth and short inter-birth interval

  • Noko Kuze
  • David Dellatore
  • Graham L. Banes
  • Peter Pratje
  • Tomoyuki Tajima
  • Anne E. Russon
Original Article


This study investigated the reproductive parameters of free-ranging rehabilitant female orangutans. We aimed to assess the factors that influence these parameters and provide information that could assist with the management of orangutan reintroduction programs. We analyzed the birth records of free-ranging female rehabilitants at Bukit Lawang, Bukit Tigapuluh, Sepilok, Camp Leakey, Kaja Island, Sungai Wain, and Meratus and compared them with reproductive parameters reported in wild and zoo populations. Females’ ages at first birth were 10.6–14.7 years, significantly earlier than those of wild and zoo orangutans. Computed inter-birth intervals (IBIs) calculated by the Kaplan–Meier method were 65.1–90.1 months; the values for Camp Leakey and Bukit Lawang rehabilitants were significantly shorter than those reported for wild Sumatran orangutans. Infant mortality rates were 18–61%; the values for Bukit Lawang and Sepilok were significantly higher than those reported for wild Sumatran and zoo orangutans. In rehabilitants, young ages at first birth and shorter IBIs may result from the high energy intake enabled by provisioning, although the possibility exists that they reflect underestimations of age on arrival at rehabilitation centers. The observed high infant mortality rate may reflect poor mothering skills due to human rearing and/or increased disease transmission. This study demonstrates that accelerated reproductive rates (younger age at first birth and shorter IBI) are common in provisioned rehabilitant females on both Sumatra and Borneo.


Orangutans Infant mortality rate Biased birth sex ratio Rehabilitation Reintroduction Provisioning 



We thank the Indonesian State Ministry of Research and Technology (RISTEK); the Indonesian Institute of Sciences (LIPI); the Indonesian State Ministry of Forestry (PHKA); the Indonesian Office for Natural Resources Conservation (BKSDA); the Malaysian Federal Economic Planning Unit; Sabah Economic Planning Unit; and Dr. Suwido H. Limin, Director of CIMTROP (Centre for International Cooperation for Management of Tropical Peatland) at University of Palangka Raya (UNPAR), for making this research possible. We would like to express our sincere thanks to the staff of each management organization: the Gunung Leuser National Park Authority (Bukit Lawang), Orangutan Information Centre/Sumatran Orangutan Society (Bukit Lawang), the Tanjung Puting National Park Office and the Orangutan Foundation International (Camp Leakey), Borneo Orangutan Survival Foundation (Meratus, Sungai Wain, and Kaja Island), Sepilok Orangutan Rehabilitation Centre, and Sabah Wildlife Department. We also thank the two anonymous referees for their valuable comments on the first draft of this manuscript. This study was partly supported by the following grants: at Bukit Lawang, the Orangutan Health Project/MU 0021622416 and Orang Utan Republik Education Initiative LP Jenkins Memorial Fellowship; at Camp Leakey, the University of Aberdeen, John Reid Trust, Royal Geographical Society (with IBG), Royal Scottish Geographical Society, Gilchrist Educational Trust, and North of England Zoological Society at Chester Zoo; and at Sepilok, the Shikata Memorial Trust for Nature Conservation, Tokyo Zoo Conservation Fund, Grant for Environmental Research Projects of The Sumitomo Foundation, JSPS-HOPE, twenty-first century COE program of the Graduate School of Science, Kyoto University (A14), Global COE program of the Graduate School of Science, Kyoto University (A06), and Global Environment Research Fund (F-061).


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Copyright information

© Japan Monkey Centre and Springer 2011

Authors and Affiliations

  • Noko Kuze
    • 1
  • David Dellatore
    • 2
  • Graham L. Banes
    • 3
    • 4
  • Peter Pratje
    • 5
  • Tomoyuki Tajima
    • 6
  • Anne E. Russon
    • 7
  1. 1.Wildlife Research Center of Kyoto UniversityKyotoJapan
  2. 2.Sumatran Orangutan Society/Orangutan Information CentreMedanIndonesia
  3. 3.Primate Immunogenetics and Molecular Ecology (PrIME) Research Group, Department of Biological AnthropologyUniversity of CambridgeCambridgeUK
  4. 4.School of Biological SciencesUniversity of AberdeenAberdeenUK
  5. 5.Frankfurt Zoological SocietyFrankfurtGermany
  6. 6.Graduate School of ScienceKyoto UniversityKyotoJapan
  7. 7.Psychology DepartmentGlendon College of York UniversityTorontoCanada

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