1. University of Washington, Seattle, WA 98195, USA.
2. ElephantVoices, 3236 Sandefjord, Norway.
3. Amboseli Trust for Elephants, Langata, Nairobi 00509, Kenya.
4. University of Stirling, Stirling FK9 4LA, UK.
5. Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08540, USA.
6. Tshuapa-Lomami-Lualaba Project, Kinshasa, Democratic Republic of Congo.
7. Save the Elephants, Nairobi 00200, Kenya.
8. Colorado State University, Fort Collins, CO 80523, USA.
9. Zoological Society of San Diego, Central Africa Program, Yaoundé, Cameroon.
10. Anglia Ruskin University, Cambridge CB1 1PT, UK.
11. Duke University, Durham, NC 27708, USA.
12. University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
13. 5 Granite Street, Peterborough, NH 03458, USA.
14. Udzungwa Mountains National Park, Sanje, Tanzania.
15. University of Massachusetts, Amherst, MA 01003, USA.
16. WildCRU, Zoology, University of Oxford, Oxford OX13 5QL, UK.
17. Sokoine University of Agriculture, Morogoro, Tanzania.
18. International Fund for Animal Welfare, Nairobi 00603, Kenya.
19. Kenya Wildlife Service, Nairobi 00100, Kenya.