[1] Princeton Univ, Woodrow Wilson Sch Publ & Int Affairs, Princeton, NJ 08540 USA
[2] Royal Soc Protect Birds, Sandy G19 2DL, Beds, England
[3] World Wildlife Fund, Conservat Sci Program, Washington, DC 20037 USA
[4] CNRS, Ctr Ecol Fonct & Evolut, UMR5175, F-34293 Montpellier, France
[5] Univ Cambridge, Dept Zool, Conservat Sci Grp, Cambridge CB2 3EJ, England
[6] Univ E Anglia, Ctr Social & Econ Res Global Environm, Norwich NR4 7TJ, Norfolk, England