“This is the story of how dedicated people prevented this giant of an insect from going extinct. It recounts the adventures they had, the joy of discovery and despondence of failure, the cooperation and support they had, the risks they took and the mistakes they made”.
The rescue of the Mercury Island tusked wētā (Motuweta isolata) from extinction is one of the most dramatic stories in New Zealand conservation. A giant wētā for all practical purpose, the Mercury Island tusked wētā is a heavy, ground-dwelling insect that has no defense from mammalian predators. It disappeared across most of its georgraphic range after the kiore (aka Polynesian rat, Rattus exulans) arrived with the first human settlers. A single population survived in marginal habitat on 13ha Ātiu / Middle Island, one of two natural fortresses in the Mercuries that had never been touched by a mammalian pest.
Thirteen wētā were captured between 1993 and 1994 as the last mammals were being eradicated from the Mercury Islands. These were used in multiple attempts to develop a captive-breeding method. Fortunately, one of these was successful so another three (one male and two females) were taken into captivity in 1998 and their progeny were used to repopulate all the Mercuries, and two other predator-free islands nearby. Only three more wētā were found on Ātiu / Middle Island after this: two were left alone and the last one, a female, was captured in January 2001 but it was infertile. The original population on Ātiu is now extinct.
Today, hundreds of Mercury Island tusked wētā live on predator-free islands, a testament to the success of our conservation effort. All are descendants of three specimens taken into captivity in 1998.
Saving the Mercury Island tusked wētā from extinction was a battle that was fought on multiple fronts. It involved fieldwork in remote locations, learning how to breed wētā in captivity – something that had never been done before – while at the same time learning about the biology and the ecology of an insect we knew next to nothing about. Many people were involved, united by a common thread: their love for conservation, and their sheer determination not to see a unique species go extinct. The “Acknowledgements” section in the book is prominent near the front and emphasizes the teamwork that was required to achieve the ambitious goal.
Ian Stringer, a scientist at Massey University and at the Department of Conservation, was one of the lead figures in the recovery of the Mercury Island tusked wētā. He was involved in the programme from the beginning, organised the timetable of recovery actions, and authored numerous publications. Nobody is as qualified as he is to narrate the story of the rescue of Motuweta isolata from extinction.
The book is not about Ian; it is about the Mercury Island tusked wētā, and it is a tribute to the whole team that worked for its conservation.
In typical selfless fashion, Ian has decided to make the book available to everyone, at no cost. Available in electronic format only, it can be downloaded from
