Re-introduction of tuatara as part of an ecological restoration project on Wakatere-papanui Island, Marlborough Sounds, New Zealand

Summary

Tuatara (Sphenodon punctatus Cook Strait), ancient reptiles reduced by introduced predators to a handful of offshore New Zealand islands, had never persisted on Wakatere-papanui Island in the Marlborough Sounds due to rat invasion. Following rat eradication across the Rangitoto island group in 1999, funded by San Diego Zoo and negotiated with multiple Maori landowners including Ngati Koata no Rangitoto ki te Tonga, Victoria University of Wellington and the Department of Conservation translocated tuatara from nearby Stephens Island in two stages. In November 2003, 89 wild-caught tuatara ranging from hatchlings to adults, removed from frog habitat to ease predation pressure on endangered native frogs, were transported by helicopter and released within a week of capture. In October 2004, 343 head-started juveniles about five years old, raised from eggs and hatchlings collected from Stephens Island rookeries in 1998-99 and reared at Nga Manu Nature Reserve, were added, giving a founding sex ratio near 1 male to 0.75 females among sexable adults. All animals underwent health screening for Salmonella, blood parasites, and internal parasites before release, though ecto-parasites were deliberately left in place given uncertain risk. Monitoring in 2006 relocated 25 percent of the 2003 cohort and 6 percent of the 2004 cohort, all of which had gained substantial weight and length, adult males averaging 43 percent mass increase over three years, but no recruitment into the population was yet detected. The project rated itself Partially Successful, noting founders are surviving and growing but it remains too early, given tuatara's long lifespan and infrequent breeding, to confirm self-sustaining recruitment.