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New Zealand has a surprising variety of lizard species for such a small country with a mild climate.

There are just over one hundred known species, and more are being discovered every year. In comparison, Great Britain, another temperate country with a similar land area, has only three. It is not the number of species itself that is remarkable - our neighbour Australia has over 600 lizard species - but rather the fact that they have become so diverse and well-adapted to our cool climate. 

 

Inland Otago jewelled gecko. Carey Knox

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Grand skink, eastern Otago. Carey Knox

 

Lizard origins

Our lizards belong to two families, the skinks and the geckos. They have evolved to flourish in almost all of our major habitat types, from forest floor to canopy, from coastal to subalpine. Indeed, a major reason we have such diversity in our lizard species is because of the wide range of habitats that are provided by New Zealand’s varied topography and climate. Another reason is that they’ve had a long time to evolve without the presence of mammals. With such diversity of habitat and history of isolation, it’s not surprising that all of our 73 native skink species and 33 gecko species are endemic, meaning that they’re found nowhere else in the world. 

 

There is general agreement that gecko were part of the original Gondwana fauna, and have been isolated in New Zealand since it split off about 80 million years ago. There is more uncertainty about the origin of our skinks. They are hardy colonisers, and may have drifted to New Zealand on rafts of vegetation. Estimates of rates of genetic change suggest that this may have happened as recently as 20 million years ago. However it is possible that skinks did not need to cross an ocean at all, as periods of low sea levels around 40 million years ago could have allowed skinks to cross land bridges all the way from New Caledonia to New Zealand. Alternatively, there is the slight possibility that skinks actually did form part of our original Gondwanan wildlife. 

All of our 73 native skink species and 33 gecko species are endemic, meaning that they’re found nowhere else in the world.

 

Adapting to Aotearoa

What is certain is that lizards have formed an important part of New Zealand’s animal life over the last tens of millions of years. They are integral to ecosystem processes, pollinating native plants and dispersing native plant seeds through eating fruit. Palaeoecologist, Trevor Worthy, is sure that New Zealand was once as alive with reptiles as it was with birds: “If you go to predator-free islands like Breaksea and Maud, in places there’s a skink every 20 cm or so, and there’s no reason to think that much of the mainland wouldn’t once have been the same. Of course, there would have been bird predators, such as weka, takahe, falcons and owls, but these would never have been in the same densities as rodents are today,” says Worthy(1).

Our temperate climate has meant our lizards have evolved some globally strange traits. Most of the world’s lizards give birth to eggs, but all bar one of New Zealand’s geckos and skinks give birth to live young. This sole New Zealand egg bearer is called, funnily enough, the egg-laying skink, and is found only in the far north. Giving birth to live young is likely to have developed as a way to cope with cooler temperatures. The lizards still produce eggs to nourish the developing young, but these eggs are retained inside the female’s body until ready to hatch. This means the mother can have some control over the temperature of the eggs when outside temperatures may drop too low for the eggs to survive on their own.  

 

Lizards have had to adapt to our cold winters. Although they don’t go into true hibernation, most  lizards will have a period of lower activity in winter. Typically they will seek out nooks and crannies where temperatures stay more mild, and will retreat deep into rock fissures, underground burrows, or dense ground level vegetation. They will eat much less often. However on fine days they will still come out to sun bask. 

“If you go to predator-free islands like Breaksea and Maud, in places there’s a skink every 20 cm or so, and there’s no reason to think that much of the mainland wouldn’t once have been the same."

Trevor Worthy

Green skink. Carey Knox

 

Today

In the 1950s, only 30 species of lizard were recognised in New Zealand. Today that number has risen to over a hundred. New species of lizards are still being discovered and described. Genetic research is uncovering differences within groups that had previously been considered one species, and new species are still being found in the wild. High on mountain ranges, on cliffs and ridge-tops in Fiordland, the fact that these animals are often in remote country combined with the fact that they’re incredibly difficult to spot means they can easily go undetected. The Awakopaka skink was discovered near the Homer Tunnel in 2014, and for a while the species was know from only one individual. Early in 2020 Carey Knox discovered eight more. There are certain to be species out there that are still unknown to humans. Even for the species we do know, there is often more about them that we don’t know. Lizard research is slow work - the cryptic nature of lizards means field work requires great patience. Owing to a lack of lizard taxonomists, almost half of our species have not yet been formally described. 

 

Tragically, close to 80% of New Zealand’s lizard species are either threatened or endangered. One of the greatest threats to the survival of New Zealand’s lizards is predation by introduced pests: cats, hedgehogs, stoats, ferrets, weasels, possums, pigs, rats and mice. It has been shown that when these predators are removed, lizard numbers return to levels of abundance. Habitat degradation and loss through land clearing and the impact of introduced grazing animals is another huge factor. Poaching for the international reptile trade puts another stress on already vulnerable populations. 

New species of lizards are still being discovered and described.

1. Patterson, G. (Jul 2000). Skinks on the edge.

Department of Conservation. Lizards. Department of Conservation.

Retrieved from: https://www.doc.govt.nz/nature/native-animals/reptiles-and-frogs/lizards/

 

New Zealand Herpetological Society (2017). Herpetofauna (native).

Retrieved from: https://www.reptiles.org.nz/herpetofauna/native

 

Patterson, G. (Jul 2000). Skinks on the edge. New Zealand Geographic, 47.

Retrieved from: https://www.nzgeo.com/stories/skinks-on-the-edge/

 

Science Learning Hub – Pokapū Akoranga Pūtaiao (17 Dec 2009). Native skinks and geckos. 

Retrieved from: https://www.sciencelearn.org.nz/resources/1381-native-skinks-and-geckos

 

Wilson, K. (2007) Lizards - Origins and diversity. Te Ara - the Encyclopedia of New Zealand.

Retrieved from: https://teara.govt.nz/en/lizards/page-2

Bibliography

Contact us:

Email Grant Norbury at: norburyg@landcareresearch.co.nz

 

Tel: +64-21-1783604

Central Otago Ecological Trust
PO Box 282
Alexandra
New Zealand

 

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© 2019 Anna Yeoman for the Central Otago Ecological Trust