Evidence against predation as a driving cause of population decline must be able to distinguish between different and interacting causes of loss. Predation can be blamed only if it removes individuals that might otherwise have lived. Detailed accounting of all causes of mortality of a given threatened species has been possible only since the development of the advanced technology summarised in Part IV. Control of stoats can benefit all native species generally, but their effects are usually confused with those of rats. The best evidence comes from rat-free Resolution, Secretary, and Anchor Islands, where stoats eradicated resident populations of Kākāpō (Strigops habroptilus), SI Kōkako (Callaeas cinerea), SI piopio (Turnagra capensis), S I tīeke (Phiesturnus carunculatus), kākāriki (Cyanoramphus sp.), and little spotted kiwi (Apteryx owenii). Stoats that invaded Maud Island and Orokonui fenced sanctuary wiped out formerly thriving refugee populations of saddlebacks/tīeke. Suppression of stoats on Waiheke Island has greatly increased nesting success and numbers of kākā (Nestor notabilis). Ferrets are deadly to larger birds, including breeding adult kiwi, weka (Gallirallus australis) and accessible seabird colonies, but are poor climbers and have never reached the most valuable islands. Weasels are generally small and now rare, but were very destructive to small prey on first arrival.