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 up to the age of 70, 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.
Radiation: diverse habitats
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 AD, 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.