1. Astrophysics Research Institute, LJMU, IC2 Liverpool Science Park, Liverpool L3 5RF, UK.
2. Faculty of Science, Liverpool John Moores University, James Parsons Building, Byrom Street, Liverpool L3 3AF, UK.
3. WWF-UK, The Living Planet Centre, Rufford House, Brewery Road, Woking GU21 4LL, UK.
4. HUTAN-Kinabatangan Orangutan Conservation Programme, 90734 Sandakan, Sabah, Malaysia.
5. School of Natural Sciences and Psychology, Liverpool John Moores University, James Parsons Building, Byrom Street, Liverpool L3 3AF, UK.
6. Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, the Netherlands.