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.
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:
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.
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.
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.
Most of New Zealand has been forested over the last 10,000 years, and it is no surprise that most of the land animals are forest-dwellers. Of the animals that have backbones (vertebrates), forest birds were and still are the dominant native life form.
With the exception of bats, New Zealand has no native land mammals, but there are 32 species of birds living in the bush. There were many more when Polynesians arrived, around 1250–1300 CE. Birds had evolved to fill almost every available habitat, in many cases adopting mammal-like characteristics. For example, moa browsed tall shrubs like giraffes.
Polynesians hunted moa and other large flightless birds to extinction. The Pacific rat they introduced also decimated populations of small, ground-nesting birds and insects.
Early European explorers and colonists remarked on the volume of the birdsong. But burning and milling trees reduced and fragmented the bush area available to birds, while introduced predatory animals depleted populations and completely exterminated some species. Around 50% of native bird species are now extinct in the North and South islands.
Some birds still flourish but other species are dwindling. In the early 2000s ornithologists estimated that New Zealand’s forests had:
Generally, the larger an area of forest, the greater variety of plants and animals it holds. The larger national parks are home to 15–20 bird species, but bush remnants (100 hectares or less) seldom support more than 10.
Two species of tuatara (a lizard-like reptile) once lived in New Zealand forests. It is thought that Pacific rats preyed on their young, eradicating them from the mainland. They survive only on offshore islands or in mainland sanctuaries. Some 30,000 live on Stephens Island in Cook Strait. Most of New Zealand’s 80 or so lizard species are forest dwellers.
Frogs were once much more widespread, with seven primitive species common on the forest floor. Four species survive as remnant populations.
Insects and their larvae are everywhere in the New Zealand bush, feeding on living, dead or rotting leaves, trunks, roots, flowers, fruit, and seeds. In one 18-month study, nearly 23,000 creatures were observed climbing up and down tree trunks in the forest. Vast numbers of insects, including cicadas, wasps, ants, beetles, moths and flies, spend long larval lives in rotting logs, bush litter, or underground, to emerge and fly briefly as adults. This makes sense, as under the forest litter the environment is fairly constant, but above ground it is often unpredictable and hazardous.
In conifer–broadleaf forests there is a greater weight of animals living under the ground than above it. Large numbers of insects spend most of their lives as subterranean grubs or caterpillars. The weight of earthworms alone exceeds that of all the birds, possums and insects above ground.
In the forest litter the most numerous animals are mites, caterpillars and grubs, springtails, litter hoppers, woodlice, millipedes, centipedes, beetles, and spiders. Predatory forest animals, whether they are insects, spiders, litterhoppers, native snails, birds or bats, depend on other bush animals for their food.
Wētā are important bush insects, providing food for lizards, and for birds such as kingfishers, moreporks, riflemen, whiteheads, grey warblers and tomtits. Other inhabitants of forest litter include carnivorous snails with large shells (up to 9 centimetres in diameter), kauri snails and an abundance of minute snails.
The biodiversity of insects and other invertebrates is much higher on small offshore islands where mice, rats, hedgehogs and other exotic mammalian predators have never been introduced – or on which conservationists have managed to eradicate them.
Despite the challenging landscape and harsh climate, some native animals make their homes in the alpine zone.
New Zealand’s black mountain ringlet butterfly looked so like a European one (Erebia epiphron) that it was classified as the same. Scientists later realised it was a distant cousin, placed it in a different genus, and renamed it Percnodaimon merula. Species of native edelweiss also look almost identical to the European edelweiss, but belong to another genus. These are examples of ‘parallel evolution’ – where life evolves in similar ways in comparable yet separate environments.
Three species of bird live almost exclusively in the mountains: the South Island’s large kea parrot, a native pipit and a rare, tiny rock wren which, in winter, forages under the snow. This last one is a living fossil with no close similarities to any other living bird (except the rifleman).
Other animals living high in the mountains are: alpine versions of geckos and skinks, spiders, dragonflies, cockroaches, wētā, grasshoppers, cicadas, flies, moths, flatworms, and a giant snail.
Animals living in rivers, streams, lakes, bogs and swamps include bitterns, harriers, wrybills, stilts, gulls, crakes, shags, kingfishers, fernbirds, grebes, teal, scaup and other native ducks.
Three kinds of native eel, a lamprey, two smelt species, seven species of bully and 25 species of galaxiids are found in New Zealand waters. There are also kōura (a small edible crayfish) and, more rarely, freshwater mussels.
Many insects, such as mayflies, stoneflies, dragonflies, caddis flies, mosquitoes, midges, and sandflies live in the water or mud as larvae, but emerge to fly as adults. Water spiders run across the surface of streams while beneath swim water beetles and water boatmen. Many waterways carry the water snail Potamopyrgus.
If a sandhopper is picked up and released in the sand dunes, it hops back across the beach towards the sea. If released a kilometre inland, it will still hop back to its beach. Catch a sandhopper on a Canterbury beach, on the east coast, and release it on a West Coast beach and it will hop back towards the east coast.
Many animals live on New Zealand’s sandy and rocky coasts. The most notable of the birds are gulls, terns and shags, but dotterels, sandpipers, plovers, herons, spoonbills, kingfishers and 57 kinds of wading bird feed on the beaches and estuaries. Many of the waders are migratory, arriving for the summer to feed at estuaries and shell banks. For example, 100,000 godwits migrate annually from Siberia and Alaska. Over 50,000 gannets nest round the coasts.
New Zealand’s only venomous animal, the katipō spider, lives in dunes behind sandy beaches. Abundant sandhoppers and kelp flies feed on rotting seaweed.
Compared with animals from other temperate land masses, many native New Zealand animals live for a long time. For example, the kākāpō bird may live for 70 years, stitchbirds for 34 years, and kiwi for at least 30 years.
Of the reptiles, some tuatara have been tagged and recorded, and are known to live to 85, but individuals can probably live to be well over 100. Skinks can live to 40. One person reported keeping a pet native gecko for 37 years and a giant Paryphanta snail for over 30 years.
Many native animals are also comparatively slow breeders. These include New Zealand pigeons, which lay only one egg at a time and which, like kākāpō, often lay no eggs at all in the years when fruit supplies are poor. Extreme examples were the moa species, which took up to 10 years to reach maturity. New Zealand’s slowest-breeding lizard (Whitaker’s skink) produces only one young at a time (it is born live rather than hatched from an egg), and then only in alternate years.
The effects of introduced predatory animals on these long-lived, slow-breeding species have been disastrous. The low reproductive rate of pigeons, kākā, kōkako, kākāpō, takahē, lizards, snails and moa has hastened their decline and, in some cases, their demise.
Some animal groups have (or had) species living in diverse environments or adopting very different lifestyles. Examples are moa species, which lived from the mountaintops to the sea. There are more than 100 wētā species in varied settings, from forests to caves, and even under rocks on Central Otago mountains where there are sub-zero temperatures.
This radiation of many related species into different habitats and lifestyles is a prominent feature of New Zealand animals.
In the words of Australian biologist Tim Flannery:
‘[New Zealand] shows us what the world might have looked like if mammals as well as dinosaurs had become extinct 65 million years ago, leaving the birds to inherit the globe’. 1
In the absence of predatory land mammals, many kinds of birds became flightless. Among them are 10 moa species (now extinct), five kiwi, six rails, two adzebills, three wrens, the kākāpō parrot, the takahē and a teal.
Though not flightless, many other birds have small wings and fly poorly. Among these are the rock wren, kōkako, saddleback, an extinct coot, an extinct owlet-nightjar, and New Zealand’s smallest bird, the rifleman. The native bats also spend a lot of time on all fours, foraging on the bush floor.
Many New Zealand insects cannot fly. Among the heaviest insects in the world are wētā, which are really flightless crickets. Over 100 species have evolved in diverse environments.
A large number of New Zealand species are, or were, giants. Fossils show that until around 1400–1500 CE, 10 species of moa roamed about. The largest species weighed well over 100 kilograms, although most were below this. The biggest eagle known to science, Haast’s eagle, had a wingspan up to 3 metres and preyed on moa. Other recently extinct big birds were a giant rail and a giant coot on the Chatham Islands, and two species of adzebills that weighed around 16 kilograms.
Still-living giants include the flightless kākāpō, which is the world’s biggest parrot, the weka and the 3-kilogram takahē. Among other big New Zealand animals are giant weevils, land snails, centipedes, earthworms, flatworms and wētā.
Although the forest birds had no mammalian predators, giant eagles and lesser hawks would have preyed on them. It is thought that in response to these threats from above, most New Zealand bush birds evolved camouflaging green, brown and grey on their upper plumage.
In general, tropical countries have a wider range of plant species than similarly sized countries with temperate climates. This rule holds for temperate New Zealand, which has only 2,500 native plant species. Most grow nowhere else. Included are 185 grasses, 93 hebe species and 20 conifers. Some 5,800 species of fungi have been given names, as have at least 2,000 lichens and 500 mosses.
Although Māori had names for most plants, the first European botanists to visit the country had difficulty putting names to some as they were so unlike any they had seen.
New Zealand has two main forest types:
These forest types often intermix.
Conifer–broadleaf forest resembles tropical jungle rather than European woodlands. Most of the trees have thick, shiny, evergreen leaves. Several species have buttressed trunks, and flowers on their trunks or stems. Like rainforest, conifer–broadleaf forest is many-layered, with tall, emergent trees. A closed roof or canopy of tall trees blocks out most of the light. Beneath are layers of sub-canopy trees and tree ferns, then a shrub layer and finally a dense layer of ferns, seedlings and other ground plants.
Contributing further to the appearance of tropical rainforest are a tangle of scrambling, climbing, hanging and perching flowering plants, ferns, mosses, lichens, liverworts, algae and fungi.
The amount of berries, fruit and seeds produced by plants in the bush varies from year to year. A warm summer and heavy flowering is usually followed by a bonanza crop of berries, fruit and seed the following autumn. Cold summers suppress flowering and fruit production.
Several plant species are known as ‘periodic flowerers’, as they produce few flowers or no flowers at all for a year or two, then produce vast numbers. Five species of southern beech tree, along with cabbage trees, flax, and the climbing kiekie are periodic flowerers, producing heavy crops of seed every two to four years. Some birds have evolved to be periodic breeders in response.
Relatives of many of New Zealand’s most distinctive trees, such as rimu, kahikatea, miro, tōtara and beech, were present when New Zealand was part of Gondwana. Some biologists used to think these trees evolved from ancestors that were ‘on board’ when New Zealand broke away from Gondwana 85 million years ago. Others now argue that these species’ ancestors disappeared from New Zealand for a while, only to be re-introduced from Australia or New Caledonia.
Until 5 million years ago New Zealand had no snow-covered mountains. Most alpine plants and animals are thought to have evolved from lowland species as the mountains rose.
Mountain plants must withstand harsh freezing and thawing, drought, fierce ice-laden gales, and high levels of ultraviolet radiation. Many cling to exposed rock faces, steep slopes, shingle slides and screes and wrest nutrients from very poor soil and rocks.
Red, silver and snow tussocks predominate in the New Zealand alpine zone, with patches of stunted, wind-shorn shrubs, sprawling heath-like plants, grass trees and dense thickets of leatherwood.
Because alpine rocks, soil and water contain little nitrogen, two kinds of mountain plants get their nitrates by eating insects. These are the sundews, which catch insects on their sticky leaves, and the bladderwort, whose roots capture insects under water.
Alpine meadows, bogs, swamps and tarns are home to a great variety of attractive mountain flowers including gentians, eyebright, edelweiss, giant buttercups, and daisies. Many shrubs have brightly coloured berries to attract the birds and lizards that disperse their seeds.
Some plants resist the fierce drying winds by growing hairy, thick, woolly or fleshy leaves. Others hold on to their old leaves to insulate the plant against the wind and help retain water. The most curious of these is the huge, cushion-shaped vegetable sheep (Raoulia eximia). Other alpine plants form mats, or become succulents and grow long taproots to survive on ever-sliding screes or shingle slips.
New Zealand rivers and lakes once supported a wide range of native waterweeds, most of which have been supplanted by foreign species such as Canadian pond weed, oxygen weed and watercress. However, bogs, swamps and the banks of rivers and lakes are often still clothed with native species such as sedges, rushes, raupō, flax, cabbage trees, toetoe, and sphagnum moss.
Raupō (bulrush) is one of New Zealand’s few deciduous plants.
To withstand parching, salt-laden winds many coastal trees such as pōhutukawa, karaka, ngaio, nīkau palms and kohekohe, have developed thick or glossy leaves. Other species, such as the native ice plants and glasswort, hold water within their leaves and can tolerate higher salt levels than many other plants.
Tough grasses such as pīngao (Desmoschoenus spiralis) and spinifex (Spinifex sericeus) used to bind New Zealand sand dunes, but they have been largely taken over by foreign marram grass (Ammophila arenaria). Mangroves (Avicennia marina) thrive in the sluggish tidal mudflats north of Tauranga.
Several plant groups which are herbaceous or small shrubs in the northern hemisphere have evolved into trees in New Zealand. These include tree-sized daisies, lilies, fuchsia and veronica (hebe). New Zealand also has giant buttercups, and forget-me-nots 1.5 metres tall. On offshore islands, too, there is a tendency for gigantism – megaherbs (large-leaved flowering plants) are prominent on the subantarctic islands. Many have smaller alpine relatives on mainland New Zealand.
Many New Zealand trees can live to a great age – kauri to 1,700 years, miro to 1,400, rimu to 1,200 and rātā to 1,100. Perching astelia lilies can live at least 60 years.
Most flowering plants on earth are hermaphrodites – male and female sex organs appear on the same flower. In the New Zealand bush, however, many species have single-sex flowers. These may be on the same plant (for example, kauri and kawakawa), or may be found as separate male and female plants (for example, most conifers, coprosmas, astelia and clematis).
Plants that have evolved from two species of the same genus are more common than in many other lands. This ability to hybridise freely means that it is easier for new species to arise.
New Zealand has over 50 species of small-leaved shrubs and low-growing trees with densely interlaced wiry, highly tensile stems. Among them are conifers, daisies, myrtles, brooms, pittosporums, and coprosmas. Collectively known as ‘divaricating shrubs’, their branches are spread apart at a wide angle.
While this feature is found elsewhere, it is nowhere as prominent as in New Zealand, where it occurs in around 10% of woody plants and has evolved independently in 18 plant families.
Some claim that these small-leaved plants with tangled stems evolved in this way to avoid being eaten by moa. In experiments, when offered these plants, emus and ostriches got so little nourishment that they would have died of starvation. Was divarication an adaptation by the plant to deter grazing birds?
This theory is challenged by others who think that divaricating plants evolved in response to climate. They argue that divarication is an adaptation to a dry, windy and frosty climate, either recently, or during past glaciations. Tangled branches may serve as both a windbreak and frost screen, and reduce water loss from the plant.
Many New Zealand trees have different leaves as saplings and as adults. Ribbonwood, mataī, lancewood, kaikomako, some hebes, certain species of kōwhai, and several other common trees and shrubs have small or fibrous leaves as saplings. But once grown to 2–3 metres (the height to which moa could reach), they develop larger leaves. Some botanists suggest this growth pattern evolved to prevent moa from eating the saplings.
New Zealand also has very few annual or deciduous plants, perhaps because of the lack of a strongly seasonal climate. Most plants are evergreen, and their leaves some shade of green, but there are curious exceptions.
Some young bush plants are dark, with brownish leaves that merge with their shadowy backgrounds, making them difficult to see. Examples of seedlings with brown leaves are lancewoods, young kauri and some sapling kahikatea and mataī. Several forest and alpine plants are so devoid of leaves that they appear to be dead.
The mountain horopito often has red and yellow blotches on its leaves. In some cases whole hillsides can appear reddish at the higher altitudes where this plant lives. Research suggests red leaves may be a protective measure against harsh ultraviolet radiation.
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