New Zealand is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island and the South Island —and over 700 smaller islands, covering a total area of 268,021 square kilometres, New Zealand is about 2,000 kilometres east of Australia across the Tasman Sea and 1,000 kilometres south of the islands of New Caledonia, Fiji, and Tonga. The country's varied topography and sharp mountain peaks, including the Southern Alps, owe much to tectonic uplift and volcanic eruptions.
New Zealand's geographic isolation for 80 million years and island biogeography has influenced evolution of the country's species of animals, fungi and plants. Physical isolation has caused biological isolation, resulting in a dynamic evolutionary ecology with examples of distinctive plants and animals as well as populations of widespread species. The flora and fauna of New Zealand were originally thought to have originated from New Zealand's fragmentation off from Gondwana, however more recent evidence postulates species resulted from dispersal. About 82% of New Zealand's indigenous vascular plants are endemic, covering 1,944 species across 65 genera. The number of fungi recorded from New Zealand, including lichen-forming species, is not known, nor is the proportion of those fungi which are endemic, but one estimate suggests there are about 2,300 species of lichen-forming fungi in New Zealand and 40% of these are endemic. The two main types of forest are those dominated by broadleaf trees with emergent podocarps, or by southern beech in cooler climates. The remaining vegetation types consist of grasslands, the majority of which are tussock.
Before the arrival of humans, an estimated 80% of the land was covered in forest, with only high alpine, wet, infertile and volcanic areas without trees. Massive deforestation occurred after humans arrived, with around half the forest cover lost to fire after Polynesian settlement. Much of the remaining forest fell after European settlement, being logged or cleared to make room for pastoral farming, leaving forest occupying only 23% of the land.
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, frogs, spiders, insects, and snails. Some, such as the tuatara, are so unique that they have been called living fossils. Three species of bats 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 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.