1. Energy and Resources Group, University of California, Berkeley, CA 94720-3050, USA ()
2. Winrock International, Suite 1200, 1621 N. Kent St, Arlington, VA 22209, USA ()
3. Centre for Environment and Society and Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK ()
4. Center for Conservation Biology, Stanford University, Stanford, CA 94305-5020, USA ()