1. E. Bulte is in the Department of Economics, Tilburg University, Post Office Box 90153, 5000 LE Tilburg, Netherlands.
2. R. Damania is in the School of Economics, University of Adelaide, Adelaide 5005, Australia.
3. L. Gillson is in the Environmental Change Institute, Biodiversity Research Group, Department of Zoology, University of Oxford, Oxford OX1 3PS, UK.
4. K. Lindsay is with the Amboseli Elephant Research Project, Amboseli Trust for Elephants, Post Office Box 15135, Langata 00519, Nairobi, Kenya.