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Tuatara

by  Charles Daugherty and Susan Keall

Tuatara have changed little since they lived alongside dinosaurs, over 220 million years ago. But these living fossils now survive in the wild only on New Zealand’s nearshore islands – where attempts are being made to ensure they don’t, like the dinosaurs, become extinct.


Life history

What are tuatara?

Tuatara are lizard-like reptiles, found only in New Zealand. Adults are between 30 and 75 centimetres long, and weigh between 250 and 1,200 grams. Males are larger than females, and have more developed spines in the crest along the neck, back and tail.

Tuatara are among New Zealand’s most famous animals, second only to kiwi. They are representative of ancient, endemic life forms.

Importance to Māori

Tuatara are of great cultural significance to Māori, and feature in some creation stories. Some iwi (tribes) view tuatara as the kaitiaki (guardians) of knowledge.

Living fossils

Tuatara are the only living representatives of an ancient lineage – the order Sphenodontia, over 250 million years old. The other reptiles – crocodiles, turtles, snakes and lizards – have many species worldwide, but just two species of tuatara survive, and only in New Zealand.

Because tuatara still look like the fossil Sphenodontians which lived during the age of dinosaurs, 220 million years ago, they are often called living fossils. Many anatomical features distinguish them from other living reptiles – for example, they have a defining pattern of openings in the skull and a unique type of haemoglobin in the blood, and males have no external reproductive organ.

Habitat and feeding

Tuatara live in burrows and are more active at night, but will come out during the day to bask in the sun. Both sexes are territorial, and males aggressively defend their territory by posturing, displaying, and fighting if necessary. Teeth are their main weapons, and a bite can cause serious injury. Tuatara are carnivorous, eating invertebrates, lizards, frogs, small tuatara, and the chicks of seabirds with which they often share burrows.

Reproduction

Tuatara mate in late summer. The male courts the female by approaching her with a proud walk. He mounts the female, positioning her with his hind legs and tail to align their reproductive openings for the transferral of sperm. The female usually lays 6–10 eggs the following spring, in a shallow nest in the ground. She may guard the nest for a few nights, then return to her own burrow. The eggs incubate for about a year, so hatchlings emerge when eggs are being laid the following season. The hatchlings receive no parental care and have to fend for themselves. Male tuatara mate annually, while females do so only once every two to seven years, depending on the availability and quality of food.

Life span

Like many other New Zealand animals, tuatara live for a long time. They reach reproductive maturity at about 15 years, and may breed for many decades. Their maximum lifespan is not known for certain, but some tuatara have reached 80 years, still looking vigorous and healthy. They may live to 100 years or more.

A cultural icon

Tuatara are a New Zealand icon. They feature in paintings and sculptures, record covers (such as Tuatara, a compilation by Flying Nun records, first released in 1985), stamps and coins. From 1967, when it replaced the sixpence, until 2006, when it was taken out of circulation, the five-cent coin featured a tuatara on a rocky shore.


Tuatara islands

Island refuges

Tuatara were once widespread and abundant on the New Zealand mainland, but after humans and predatory mammals arrived, they gradually became restricted to 32 nearshore islands. Many of these islands were tiny – less than 10 hectares, and some as small as only 1 hectare. A few, such as the Poor Knights Islands off the Northland coast, or Stephens Island in Cook Strait, were never invaded by rats, and had few of the other mammals that threaten native animals.

These islands have become refuges for many native species, especially lizards, birds and invertebrates.

Two species

The common tuatara (Sphenodon punctatus) occurs on islands off the north-eastern coast of New Zealand, and on some islands in Cook Strait. The Brothers Island tuatara (Sphenodon guntheri) survived only on the tiny, 4-hectare North Brother Island, in Cook Strait. Two new populations of the Brothers Island tuatara have been created on Tītī Island in the Marlborough Sounds and Matiu (Somes Island) in Wellington Harbour.

The two tuatara species look similar, but have genetic differences. Tuatara bones have been found the entire length of New Zealand. Where dated, they are usually a few hundred to 5,000 or more years old. It is not known whether these bones are from the two living species, or others now extinct.

A tuatara in your trousers

One cold, wet night on Stephens Island in Cook Strait, researcher Alison Cree was bitten by a tuatara. It let go after 15 minutes, leaving her with bruised fingers. She felt she got off lightly: ‘My pain, though, seemed small compared with the terror that must have seized a male colleague who had a tuatara run up his trouser leg. Fortunately, the adventurous reptile was subdued before causing any major harm.’ 1

Numbers

Tuatara can live in remarkably dense populations. Most tuatara islands have 50–100 tuatara per square hectare – so an island of only 10 hectares may have a population of hundreds. Larger islands with many seabirds and invertebrates, which tuatara eat, may have greater densities. The largest population is on Stephens Island (Takapourewa), where there are estimated to be as high as 2,500 per square hectare in some places, and a total of at least 30,000. The total number of tuatara on all the islands is probably between 50,000 and 100,000.

Footnotes
  1. Charles Daugherty and Alison Cree, ‘Tuatara: a survivor from the dinosaur age.’ New Zealand Geographic 6 (April–June 1990): 60. › Back

Decline and recovery

Mainland extinction

Despite large numbers of tuatara on some islands, populations continued to become extinct until recently. When Polynesian settlers arrived in New Zealand, about 1250–1300 AD, they brought with them kiore or Pacific rats (Rattus exulans), which preyed on tuatara. By the time of European settlement, in the 1840s, tuatara were almost extinct on the mainland. Some islands provided temporary havens, but soon these too began to be invaded by rats and other mammalian predators.

Legal protection was granted to tuatara and the islands they occupied in 1895, but the reptiles continued to decline. The most recent localised extinction was on Whenuakura Island, off the Coromandel Peninsula, around 1984. Since then, active conservation management has reversed the decline, and new populations have become established on predator-free islands.

Path to recovery

In the mid-1980s the New Zealand Wildlife Service and its successor, the Department of Conservation, developed ways to eradicate rats from islands. Rats have now gone from almost all of the tuatara islands, making them safe for many threatened native species.

In addition, collecting and incubating eggs, breeding in captivity, and moving tuatara to rat-free islands have increased the number of island populations to 37. In 2005, 70 adult tuatara from Stephens Island (Takapourewa) were moved to Karori Wildlife Sanctuary in Wellington – they were the first mainland population in hundreds of years. Many new tuatara populations are planned for islands and mainland reserves that have been freed of predators.

The case of Little Barrier Island (Hauturu)

On Little Barrier Island (Hauturu), in the Hauraki Gulf, a threatened population of tuatara was saved from extinction. In 1991 none had been seen there for 14 years, but the kiore were thriving. Tuatara were feared extinct from the largest island (3,000 hectares) on which they had previously lived. Surveys in 1991–92 found eight surviving adult tuatara, which were caught and housed safe from the rats. These eventually bred, their eggs were incubated in captivity, and the young were raised in rat-free enclosures. Kiore were eradicated from the island in 2004, and in 2006 the first of more than 100 young tuatara were set free. Committed action by scientists, conservationists, iwi (tribes) and volunteers has given hope that tuatara will once again be plentiful on Little Barrier Island.

Cooling down

Some Māori muttonbirders tell of an interesting use for tuatara on hot days. They would drape the cold-blooded reptiles across their stomach to cool themselves down. The effect would probably be short-lived – when tuatara warm up they become increasingly active.

Seeing tuatara in the wild

Until 1998, tuatara could be found only on island sanctuaries that were closed to the public. As an experiment, they were introduced to Somes Island (Matiu), in Wellington Harbour, and Tiritiri Matangi Island, near Auckland. Many people have visited these ecological restoration projects and seen tuatara.

In 2007, tuatara were most easily seen at the Karori Wildlife Sanctuary, 10 minutes from downtown Wellington. You will eventually be able to see them at other ecological restoration sites on the mainland.


External links and sources

More suggestions and sources

More links and websites


How to cite this page: Charles Daugherty and Susan Keall, 'Tuatara', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/en/tuatara/print (accessed 15 August 2018)

Story by Charles Daugherty and Susan Keall, published 24 Sep 2007