[1] Univ Auckland, Sch Biol Sci, Auckland 71142, New Zealand
[2] Univ Auckland, Dept Stat, Auckland 71142, New Zealand
[3] Zealandia Sanctuary, Zero Invas Predators, POB 9267, Wellington 6141, New Zealand
[4] UCL, Ctr Biodivers & Environm Res, Dept Genet Evolut & Environm, Gower St, London WC1E 6BT, England
[5] ZSL, Inst Zool, Regents Pk, London NW1 4RY, England