Wild male orangutans plan their travel and communicate their plans to other orangutans, according to research published September 11 in the open access journal PLOS ONE by Carel van Schaik and colleagues from the Anthropological Institute and Musuem in Zurich, Switzerland.
Although previous studies have shown that great apes can plan for future needs, it has not been clear whether and how they do so in the wild. In this study, authors studied the calls of orangutans that live in dense tropical forests, often out of sight from others in their population. Adult males emit loud, long vocalizations audible over a kilometer away to establish their status amongst other males or signal to females. Tracking over 200 calls made by 15 adult males in the wild, the researchers found that males faced the direction they planned to travel and emitted 'long calls' in that direction the night before a journey. If they changed travel plans the following morning, males were more likely to follow up with a call in the new direction planned. Co-author Karin Isler expands, "We found that males emitted long calls mostly facing the direction they travelled a few hours later, or even after a night's rest."
Females within earshot frequently followed the path taken by the male and changed direction when the male did. Subordinate males who heard these calls tended to avoid following a similar path.
When orangutans choose to plan their trips in advance is not yet clear; some of the reasons suggested include avoidance of a known rival, searching for mates or food. The researchers add that such planning abilities may not be limited to orangutans, and may exist in other apes or large-brained animals.
Citation: van Schaik CP, Damerius L, Isler K (2013) Wild Orangutan Males Plan and Communicate Their Travel Direction One Day in Advance. PLoS ONE 8(9): e74896. doi:10.1371/journal.pone.0074896
Financial Disclosure: This research was supported by Universitas Indonesia and Universitas Syiah Kuala, the Wildlife Conservation Society (New York), the L.S.B. Leakey Foundation, the Wenner-Gren Foundation for Anthropological Research and the Swiss National Science Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interest Statement: The authors have declared that no competing interests exist.
Disclaimer: This press release refers to upcoming articles in PLOS ONE. The releases have been provided by the article authors and/or journal staff. Any opinions expressed in these are the personal views of the contributors, and do not necessarily represent the views or policies of PLOS. PLOS expressly disclaims any and all warranties and liability in connection with the information found in the release and article and your use of such information.
About PLOS ONE: PLOS ONE is the first journal of primary research from all areas of science to employ a combination of peer review and post-publication rating and commenting, to maximize the impact of every report it publishes. PLOS ONE is published by the Public Library of Science (PLOS), the open-access publisher whose goal is to make the world's scientific and medical literature a public resource.
All works published in PLOS ONE are Open Access. Everything is immediately available--to read, download, redistribute, include in databases and otherwise use--without cost to anyone, anywhere, subject only to the condition that the original authors and source are properly attributed. For more information about PLOS ONE relevant to journalists, bloggers and press officers, including details of our press release process and our embargo policy, see the everyONE blog at http://everyone.