The giant Haast's eagle died out when humans hunted its main prey, the moa, to extinction. The forests were dominated by birds, and the lack of mammalian predators led to some like the kiwi, kākāpō, weka and takahē evolving flightlessness.
The arrival of humans, associated changes to habitat, and the introduction of rats, ferrets and other mammals led to the extinction of many bird species, including large birds like the moa and Haast's eagle.
Other indigenous animals are represented by reptiles (tuatara, skinks and geckos), frogs, such as the protected endangered Hamilton's Frog, spiders, insects (wētā), and snails. Some, such as the tuatara, are so unique that they have been called living fossils.
Three species of bats (one since extinct) were the only sign of native land mammals in New Zealand until the 2006 discovery of bones from a unique, mouse-sized land mammal at least 16 million years old. Marine mammals, however, are abundant, with almost half the world's cetaceans (whales, dolphins, and porpoises) and large numbers of fur seals reported in New Zealand waters.
Many seabirds breed in New Zealand, a third of them unique to the country. More penguin species are found in New Zealand than in any other country, with 13 of the world's 18 penguin species.
Since human arrival, almost half of the country's vertebrate species have become extinct, including at least fifty-one birds, three frogs, three lizards, one freshwater fish, and one bat. Others are endangered or have had their range severely reduced. However, New Zealand conservationists have pioneered several methods to help threatened wildlife recover, including island sanctuaries, pest control, wildlife translocation, fostering and ecological restoration of islands and other protected areas.