New Zealand was largely untouched as an island until very late in human history- the first settlers were the Maori, who came in around the 13th century. For comparison, this was well into the Middle Ages in Europe. This allowed thousands of endemic species to grow unbothered which, like with the Galapagos Islands, led to some really interesting creatures. In the case of New Zealand, there are no native mammals (except some tiny bats) which has let the birds really shine and grow in unique ways.
One of the first to go was the Moa, a huge ostrich-like bird that the Maori hunted to extinction. We saw a Moa skeleton in Auckland. HUGE.