Talking about tuatara

21:48, Nov 14 2012

Tuatara - our "living fossil", are the last remaining member of their reptile family and haven't really changed very much in 225 million years.

Tuatara are reptiles but not lizards, and they have changed little since they walked the Earth with their dinosaur cousins. All of their relatives died out about 60 milllion years ago yet tuatara somehow remained. 

Some iwi consider tuatara to be their ancestors or kaitiaki (guardians) of knowledge, which given their age and incredible endurance is probably quite a fitting reference.

There are two species of tuatara, the Stephens Island tuatara (Sphenodon punctatus) and the Brothers Island tuatara (Sphenodon guntheri). There is also a Northern subspecies of tuatara. 

If you've ever had the opportunity to see a tuatara up close, or even hold one, you'll know that they are just amazing creatures. They can grow to 75cm long and are all muscle. The "spines" on their back (tuatara means "spiny back" in Maori) are all for show, actually feel very soft and males can increase bloodflow to them. This raises the spines, makes the male look bigger and tougher and is designed to attract the lady tuatara.


Age is no barrier to tuatara breeding - and nowhere could this be better described than at the Southland Museum, home to Henry the 115-year-old tuatara. Henry became a father for the first time at 111 years old after previously showing no interest in female tuatara. Keepers discovered a tumour near his "man bits" and after that was removed, Henry has been making up for lost time. I think he's an example to us all!

Tuatara breeding occurs after they reach sexual maturity after about 15 years, but as with everything tuatara, reproduction is a slooooowwwww process.  Females only feel like mating (depending on conditions and food supply) about once every two to five years, and after nine months or so she lays eggs in a warm spot in the soil, which take another year or more to hatch out. Tiny tuatara must make themselves scarce, since adult tuatara will eat anything moving that fits in their mouth, so the young ones get around this by hunting during the day, and hiding at night when the adult tuatara are out and about.

Tuatara, like other reptiles, are "cold-blooded", which isn't a very accurate term, but it means that instead of regulating their own body temperatures (like mammals), tuatara gain their temperature from their surrounding environment.  According to Te Ara Encyclopedia, Maori on the muttonbirding islands used to drape the cool tuatara on their stomachs to help them cool down.

Tuatara used to be found all over New Zealand, but they began to disappear from the mainland about the same time Polynesian rats or kiore got here. By the time Europeans began settling here in the 1840s (as well as our omnipresent introduced rats) the tuatara were pretty much gone.

Once again, predator-free islands came to the rescue of our native species. On islands which had remained free of rats, tuatara survived and thrived. However, the rats (being good swimmers and hitchhikers) soon made their way to many of the islands where tuatara existed and risked their survival again.

In the 1980s the Wildlife Service and then Department of Conservation began to excel at removing rats and other predators from islands, creating more and more predator-free natural havens, and that has been the saving grace for tuatara (and other wildlife).

Thanks to these lifeboats for wildlife, the Brothers Island tuatara managed to hang in there on just four hectares! After pioneering the rat eradication techniques, the next step for DOC was to work on translocations. By moving tuatara to predator-free islands and predator-free mainland sanctuaries, new populations have been created or supported all over the country.

The most ambitious tuatara transfer happened last month, thanks to Air New Zealand supporting DOC's "Great Tuatara Transfer", which moved 260 tuatara from Stephenson's Island to a range of eco-sanctuaries around the country, including Orokonui Sanctuary in Dunedin, which started the first South Island mainland population in 150 years.

Though the decline in tuatara caused by predators has now been well and truly reversed, it seems that once again this modern-day dinosaur is at risk, this time thanks to climate change.

Scientists have discovered that the temperature of the soil that the eggs are buried in determines what sex the hatchlings will be. If the soil temperature is 22 degrees Celsius or more, all males are hatched; if it is just a couple of degrees cooler, only females hatch out.  A warming climate could well spell the end for our living fossil, though we are able to control artificial incubation temperatures. Just another reason to make sure we are doing everything we can to combat climate change, if only to help protect a creature who has survived all other catastrophes over the past 200 million years.

Probably the best place to see tuatara in the wild is at Zealandia, just 10 minutes from downtown Wellington. But look closely! The last time I was looking at tuatara there, I started chatting to a young American girl who said "I've been standing here for half an hour and I still haven't seen one." When I pointed one out to her, she said "Near that stick?" until the "stick" moved, surprising her greatly!

Have you been lucky enough to see tuatara? Did you know about the impact of climate change on them? I'd love to hear your stories!

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