Currently, S. guntheri is ranked as Vulnerable by the IUCN Red Data Book, whereas S. punctatus has been delisted. The decline of tuatara on the main North and South Islands of New Zealand and on many offshore islands has been attributed to predation by introduced mammals, especially rats. Innovative and aggressive campaigns against introduced mammals by the New Zealand Department of Conservation, combined with research on behavior and reproductive biology by universities and partnerships with zoos in New Zealand and the United States, have led to the beginnings of a resurgence by both species. Within the range of the northern form, introduced rats have been removed from seven islands where tuatara populations were dangerously low or were showing recruitment failure. An additional population has been estab lished on an island within the form's historic range. Attempts are under way to establish two new populations of S. guntheri on islands from which rats have been removed, and additional restoration plans are being formed that will benefit the Cook Strait S. punctatus.
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