Many of New Zealand’s animals and plants are not found elsewhere – these are known as endemic species. For example, over 80% of the 2,500 species of native conifers, flowering plants and ferns are found nowhere else. And of the 245 species of birds breeding in New Zealand before human arrival, 71% were endemic. This high rate is mainly the result of the country’s long isolation from other land masses.
We tend to focus on larger animals and plants such as birds and trees because they are easily visible, but they comprise only about 5% of New Zealand’s estimated 70,000 native species living on land. The vast majority of living things in New Zealand are small or hidden life forms.
Land of fungi and insects
The best guess of the numbers of land-based native plants and animals is around 70,000 species. Insects and fungi dominate, each having an estimated 20,000 species – many are not yet described. Among some animal groups, new species are being discovered faster than scientists can cope with them.
Around 30,000 species of land-based life forms have been given scientific names. The approximate numbers of named, native species are:
- 6,000 beetles
- 5,800 fungi
- 2,500 higher plants
- 2,000 moths and butterflies
- 1,100 spiders
- 1,000 land snails
- 550 mosses
- 500 liverworts and hornworts
- 170 earthworms
- 85 millipedes
- 91 birds that breed and feed on land
- 80 skinks and geckos
- 38 freshwater fish
- seven frogs
- three bats
- two tuatara.
What is missing?
In New Zealand, whole groups of animal species common in other land masses are absent, or very poorly represented. The most notable group is land mammals: apart from two surviving bat species, there are none. Almost everywhere else on earth, mammals are prominent or dominant. There is no evidence that reptilian groups such as iguanids (a type of lizard) and snakes ever established in New Zealand. Groups such as ants, and many other families of animals without backbones, are also poorly represented.
Just because species or whole groups of plants and animals do not naturally live in New Zealand now does not mean that they never lived there. Species such as casuarina (she-oak), eucalyptus (gum tree), banksia (bottle-brush), acacia, protea, coconuts, crocodiles and turtles are found in the fossil record but died out over the last 15 million years as the climate cooled.
Big groups of small creatures
Certain animal groups in New Zealand have exceptionally large numbers of species. There are 900 species of tiny snail living in bush litter, and over 100 species of wētā (cricket-like insects). At one site, as many as 134 different species of moth were caught in a single night.
Fewer species, high endemism
New Zealand, like other temperate land masses, has fewer plant and animal species than more tropical lands. But as in many isolated islands, a high proportion of these are found nowhere else.
Among the most distinctive life forms are ancient animals from the supercontinent Gondwana. The land that was to become New Zealand broke away from Gondwana some 85 million years ago. Ancient animals that have descended from Gondwanan ancestors include Jurassic tuatara, skinks and frogs, velvet worms (peripatus), native wrens, mayflies, caddis flies, sandflies, and at least 170 species of earthworm, some very large. These living fossils have been isolated on the islands of New Zealand since the days of the dinosaurs.
Most of New Zealand’s native plants and animals flew, floated or were blown from Australia or the Pacific Islands over the past 85 million years. All had to survive subsequent changes in environment and climate. They have filled every habitat of the country and about 600 smaller offshore islands – from the subtropical Kermadecs to the nearly subantarctic Auckland and Campbell island groups. In environments which have long been isolated from other land masses, such as islands, new arrivals often face less competition from other species. They can find greater opportunities to evolve into different forms and move into different habitats.