Establishing additional populations of the wetapunga on islands in the Hauraki Gulf, North Island, New Zealand

Summary

The wetapunga (Deinacrida heteracantha), one of the world's largest insects and reduced to a single wild population on New Zealand's predator-free Te Hauturu-o-Toi (Little Barrier Island) after mammalian predators eliminated it elsewhere, was the subject of a captive-breeding and island-establishment program led by the Department of Conservation, Auckland Zoo and Butterfly Creek. Small founder groups collected from Hauturu in 2008, 2009 and 2012 (totaling 21 pairs) bred readily in captivity, producing around 350 hatchlings from the earliest cohorts reared individually to avoid cannibalism, a labor-intensive method later supplemented by communal rearing trials at Auckland Zoo that showed comparable survival with far greater efficiency; the 2012 founders alone produced over 1,500 first-generation nymphs by 2014. Fifty mid-to-late instar wetapunga were released onto predator-free Motuora Island in 2010 and Tiritiri Matangi in 2011, each placed in bamboo refuges near natural daytime shelter, followed by supplemental releases of over 750 more nymphs in 2014 and, in a shift toward earlier-instar, higher-volume releases, 944 second-generation nymphs directly into natural refuges on Motuhoropapa Island in June 2015. Baited tracking tunnel surveys in June 2015 confirmed the presence of a first island-born generation at both Motuora and Tiritiri Matangi, though full self-sustaining status will not be assessed until mixed-age populations persist ten years post-release. Difficulties included early struggles identifying suitable food for first-instar nymphs and the strain unexpectedly high breeding success placed on captive rearing capacity. The project rates itself partially successful, citing the first confirmed island-born generation and validated communal rearing methods as key milestones while full establishment remains unproven.