About the Authors

Marc Ancrenaz

To whom correspondence should be addressed. E-mail: hutan1@tm.net.my

Affiliation Kinabatangan Orang-utan Conservation Project, Sandakan, Sabah, Malaysia

Olivier Gimenez

Affiliations CEFE/CNRS, équipe Biométrie et Biologie des populations, Montpellier, France, Institut de l'Ingénierie de l'Information de Santé, équipe TIMB, Faculté de Médecine, La Tronche Cedex, France

Laurentius Ambu

Affiliation Sabah Wildlife Department, Wisma Muis, Kota Kinabalu, Sabah, Malaysia

Karine Ancrenaz

Affiliation Kinabatangan Orang-utan Conservation Project, Sandakan, Sabah, Malaysia

Patrick Andau

Affiliation Sabah Wildlife Department, Wisma Muis, Kota Kinabalu, Sabah, Malaysia

Benoît Goossens

Affiliation Biodiversity and Ecological Processes Group, Cardiff School of Biosciences, Cardiff University, Cathays Park, Cardiff, United Kingdom

John Payne

Affiliation World Wildlife Fund-Malaysia, Kota Kinabalu, Sabah, Malaysia

Azri Sawang

Affiliation Kinabatangan Orang-utan Conservation Project, Sandakan, Sabah, Malaysia

Augustine Tuuga

Affiliation Sabah Wildlife Department, Wisma Muis, Kota Kinabalu, Sabah, Malaysia

Isabelle Lackman-Ancrenaz

Affiliations Kinabatangan Orang-utan Conservation Project, Sandakan, Sabah, Malaysia, Pittsburgh Zoo, Pittsburgh, Pennsylvania, United States of America

Competing Interests

The authors have declared that no conflicts of interest exist.

Author Contributions

MA, JP, AT, and ILA conceived and designed the experiments. MA, BG, and AS performed the experiments. MA, OG, and KA analyzed the data. LA took part in the general design of the surveys and obtained the necessary authorization to conduct helicopter flights. PA obtained the authorizations to conduct these surveys in Sabah. MA, JP, and ILA contributed reagents/materials/analysis tools. MA, OG, and BG wrote the paper.