Living dinosaurs on the way to recovery
The tuatara is a lizard-like creature that is only found on certain small islands around New Zealand and in a number of mainland sanctuaries.
It is not a true lizard but a 'living fossil', a survivor of a group of animals that were once more widespread. They look very much like lizards but their skeleton shows many differences.
Tuatara are the only existing members of the Order Sphenodontia, which was well represented by many species during the age of the dinosaurs, some 200 million years ago. All species apart from the tuatara declined and eventually became extinct about 60 million years ago. Only tuatara survived to become a 'living fossil'.
Endangered species
Despite large numbers of tuatara on some islands, the species is still endangered.
When Polynesian settlers arrived in New Zealand, about 1250 - 1300AD, they introduced kiore / Pacific rats which preyed on tuatara, one of the world’s oldest species.
By the time European settlement began in the 1840s, tuatara were almost extinct on the mainland. Some islands provided temporary havens, but soon these too were invaded by rats and other mammalian predators.
As early as 1895 legal protection was granted to tuatara and the islands they occupied, but the reptiles continued to decline.
First conservation work
In the mid-1980s the New Zealand Wildlife Service and its successor, the Department of Conservation (DOC), began to develop ways to eradicate rats from islands. Nowadays these predators are gone from almost all of the tuatara islands, making them safe for many threatened native species.
In addition to eradicating predators other measures to protect tuatara were introduced. Collecting and incubating eggs, breeding in captivity, and moving tuatara to rat-free islands have increased numbers.
In 2005, 70 adult tuatara from Stephens Island (Takapourewa) were moved to the Karori Wildlife Sanctuary in Wellington. They were the first mainland population in hundreds of years.
Tuatara on Little Barrier Island
On Hauturu / Little Barrier Island, in the Hauraki Gulf between Auckland and the Coromandel, a threatened population of tuatara has been saved from extinction thanks to a DOC initiative.
When DOC started a captive management programme on Little Barrier in 1991, no tuatara had been seen on the island for 14 years - though the rats continued to thrive. Then eight surviving adult tuatara were discovered, captured and held safe from the rats.
As a result of the safe environment the tuatara eventually bred. The eggs were incubated in captivity, and the young were raised in rat-free enclosures.
Kiore were completely eradicated from the island in 2004, and in 2006 the first of more than 100 young tuatara were set free.
Tuatara in the wild
Until 1998, tuatara could only be found on island sanctuaries that were closed to the public.
As an experiment, to make them more accessible, they were introduced to Somes Island (Matiu), in Wellington Harbour, and Tiritiri Matangi Island, near Auckland. The risk was rewarded and many people have now visited these ecological restoration projects and seen tuatara.
A living dinosaur
A New Zealand native, the tuatara are rare, medium-sized reptiles. An adult can grow up to 24cm in length and weigh about 500 grams.
Though there are physical resemblances, tuatara are very different to lizards, crocodiles and amphibians. Their primitive body structure suggests that they have changed little in the past 220 million years, making them one of the world’s oldest and most un-evolved species. The Maori translation of tuatara is ‘spiny back’.
Tuatara are vulnerable to predators as they are slow breeders. Females lay soft-shelled eggs nine months after mating, and the eggs take 12 - 15 months to hatch. The sex of the baby depends on the soil temperature.
It takes anything from 9 - 14 years for a juvenile tuatara to mature, and they reach their full size at 25-35 years old. The tuatara lives for 60 - 100 or more years.
Tuatara are found on around 35 islands. Seven of these are in Cook Strait, between the North and South islands, and are home to an estimated 45,500 animals. About 10,000 Northern tuatara are spread over islands in the Hauraki Gulf, off Northland, the Coromandel Peninsula and the Bay of Plenty.
More information:
Zealandia - the Karori Sanctuary experience
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