Evidence suggests that the tuatara cannot persist in areas where rats are present due to competition with these fast breeding rodents. They do not occur on Brothers Island but there is concern that Polynesian rats, Rattus exulans
, which occur on other islands, may spread by boats and on driftwood to Brothers Island (7). Tuatara are also predated on by introduced animals such as dogs and cats (8). Furthermore, scientists warn that climate change could have significant impact on this species as the eggs are sensitive to small changes in temperature that could alter the sex ratio and unbalance the reproductive success of a population. Tuatara have, however, survived 200 million years, so may have mechanisms to cope with climate change, though it is feared that the climate change of the future may occur at a faster rate than tuatara can adapt, physiologically or behaviourally (9).