About the Authors

Serge A. Wich

sergewich1@yahoo.com

Affiliations Anthropological Institute and Museum, University of Zurich, Zurich, Switzerland, Sumatran Orangutan Conservation Programme (PanEco-YEL), Medan, Sumatra, Indonesia

Michael Krützen

Contributed equally to this work with: Michael Krützen, Adriano R. Lameira

Affiliation Anthropological Institute and Museum, University of Zurich, Zurich, Switzerland

Adriano R. Lameira

Contributed equally to this work with: Michael Krützen, Adriano R. Lameira

Affiliation Behavioural Biology, Utrecht University, Utrecht, The Netherlands

Alexander Nater

Affiliation Anthropological Institute and Museum, University of Zurich, Zurich, Switzerland

Natasha Arora

Affiliation Anthropological Institute and Museum, University of Zurich, Zurich, Switzerland

Meredith L. Bastian

Affiliation Department of Anthropology, Boston University, Boston, United States of America

Ellen Meulman

Affiliation Anthropological Institute and Museum, University of Zurich, Zurich, Switzerland

Helen C. Morrogh-Bernard

Affiliation University of Cambridge, Wildlife Research Group, Cambridge, United Kingdom

S. Suci Utami Atmoko

Affiliation Fakultas Biologi, Universitas Nasional, Jakarta, Indonesia

Joko Pamungkas

Affiliation Primate Research Centre, Bogor Agricultural University, Bogor, Indonesia

Dyah Perwitasari-Farajallah

Affiliation Primate Research Centre, Bogor Agricultural University, Bogor, Indonesia

Madeleine E. Hardus

Affiliation Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands

Maria van Noordwijk

Affiliation Anthropological Institute and Museum, University of Zurich, Zurich, Switzerland

Carel P. van Schaik

Affiliation Anthropological Institute and Museum, University of Zurich, Zurich, Switzerland

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: SW MK AL CvS. Performed the experiments: SW AL MK CvS. Analyzed the data: SW AL MK CvS NA AN. Contributed reagents/materials/analysis tools: SW MK NA AN AL EM MB HMB MH MvN JP DPF SSUA. Wrote the paper: SW AL MK CvS.