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Why are tuatara found mainly on offshore islands rather than New Zealand’s main islands?
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tuatara
The species is the sole living member of the reptile order Rhynchocephalia.
Tuatara were once widespread across New Zealand’s main islands, but they are now found primarily on offshore islets due to the introduction of non-native predators.
The arrival of the Maori people introduced the kiore, or Polynesian rat, which preys heavily on tuatara eggs and young. Furthermore, the introduction of other mammals—such as cats and pigs—has rendered the tuatara seriously threatened with extinction on the main islands. Consequently, these reptiles have survived in the wild only in areas where such invasive species are absent or controlled, such as the roughly 30 islets off the northeast coast of the North Island and a handful of islets in the Cook Strait.1