Tuatara

TUATARA Tuatara are recognised internationally and within New Zealand as a species in need of active conservation management.

Contents Page

3.

Over View Metabolism Evolution of Tuatara Tuatara Species

7.

The Problem Past Distribution Current Distribution Lifespan and Breeding Cycle

11.

The Cause Global warming Predators Evidence of Rat Impact

15.

Current Solutions Captive Bleeding Program Eradication of Mammals Translocation The Case of Little Barrier Island (Hauturu)

2

Overview Research into the life of the Tuatara only started in last 60–70 years. This is due to the remote locations of the Tuatara. This means that due to the slow metabolism and long life spans of the Tuatara, little solid data can be found on the plight of the population over time.

Metabolism Tuatara have very slow metabolism. The average body temperature of an active Tuatara is 11°C; the average body temperature of other reptiles is not lower than 14.4°C. Tuatara breathe once every 7 seconds when active and once an hour when resting.

Average Length of Adult Tuatara

Tuatara have they slowest growth rates of any reptile, continuing to grow for the first 35 years of their lives.

Male

Female

45 cm 56 cm

4

The Evolutionary Tree of Reptiles

Evolution of Tuatara Tuatara are the only surviving relatives of a group

Mammal-like Reptiles

Mammals

of reptiles called the ‘break head’ which existed in New Zealand over 200 million years ago. They became extinct about 60 million years ago.

Turtles & Tortoises

Although Tuatara have remained largely physically unchanged over a long periods of Old Breakhead

Tuatara

evolution, they are evolving at a DNA level faster than any other animal yet examined. This was discovered after comparing recovered DNA

Earliest Reptiles

Snakes & Lizards

sequences from the bones of ancient Tuatara up to 8000 years old with that of living Tuatara.

Bird-like Reptiles

Birds

Crocodiles

Dinosaurs

5 The Northern Tuatara (Sphenodon Punctatus)

Tuatara species Distribution

Tuatara Species Current taxonomy recognises two species of Tuatara, and one of these is considered to comprise two sub-species. The Northern Tuatara (Sphenodon Punctatus) is present on islands from the Bay of Plenty north. The Cook Strait Tuatara (S. Punctatus), an unnamed subspecies, is present on Takapourewa and the Trio Islands The Cook Strait Tuatara Sub species (S. Punctatus)

in Marlborough Sounds. The other species

The Brothers Island Tuatara (S. Guntheri)

known naturally from one small island in the

is the Brothers Island Tuatara (S. Guntheri) Marlborough Sounds, they are slightly smaller than the other Tuatara and lived only in a patch of scrub on the top of North Brother Island.

Past Distribution

6

The Problem The Department of Conservation and Scientists at Victoria University have estimated that by 2085 Tuatara will be extinct in the wild if we don’t intervene.

Past Distribution Tuatara were once widely distributed over the North and South Islands. They declined during

Decline of Tuatara on the Mainland Thriving

the last 1000–2000 years and probably became extinct on the mainland by the late 1700’s. The decline was most likely due to mammals that arrived with the settlers.

When Polynesian settlers arrived in New Zealand, about 1250–1300 AD, they brought with them Kiore rats. By the time of the European settlers (who brought the Norway rats and Ship Rats), in the 1840’s, Tuatara were almost extinct on the mainland.

Extinct 1200’s

1800’s

8

10,000 Northern Tuatara

Population Distribution

Current Distribution Tuatara once lived throughout the mainland of New Zealand but survived in the wild on 32 offshore islands. These islands are mostly free of rodents and other introduced mammalian predators. Tuatara have been translocated to a further three islands that they presumably inhabited in the past.

Northern Tuatara are estimated to have a total population of approximately 10,000. Cook Strait Tuatara are estimated to have a total population of approximately 45,000. At least 30,000 of

45,000 400 Cook Strait Tuatara

Brothers Island Tuatara

the Cook Strait Tuatara are on Takapourewa.

Brothers Island Tuatara are the least numerous with only 400 adults.

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2.

3.

Lifespan and Breeding Cycle The average lifespan of Tuatara is estimated to be 60 years, but they can live to be well over

4.

100 years old. Some experts believe that captive Tuatara could live as long as 200 years. Tuatara become sexually mature in their early teens; between the age of eleven and fifteen.

1.

Female Breeding cycle

Male Tuatara breed every year. Female Tuatara

5.

Takes an average of four years

breed every 2–6 years, on average every four.

The stages of the female breeding cycle are: 1. Egg yolk production can take about 2–3 years.

2. Mating season takes place in mid summer 3. Ovulation happens within 1–2 months.

4. The female Tuatara caries the eggs for 8–9 months. The embryo does not develop. Egg shelling occurs gradually throughout winter.

5. Females congregate to lay eggs in early spring. They dig nests, often digging up existing nests.

Females can lay between 1–19 eggs.

6. Eggs take 11–16 months to hatch.

The sex determining stage occurs and then the embryo hibernates in the egg during the winter.

7. The young hatch in spring.

6.

7.

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The Cause The Tuatara population has dwindled over the few hundred years. This is due to environmental causes such as Global Warming and the affects of human settlement in New Zealand such as the introduction of mammals.

Global Warming

Temperatures effect on Sex of hatchlings

New Zealand’s cool climate suits the Tuatara’s

male Tuatara outnumber females by a ratio of 1:7

The sex of the hatchlings is determined by the

slow rate of living. The prolonged reproductive

on islands near the top of the South Island.

temperature that the developing embryos are

cycles of female Tuatara may be adaptations to a

exposed to during the sex determining stage.

temperate environment with cool summers and

Tuatara could survive if nesting female Tuatara

cool, but not freezing, winters. The temperature

change their behavior and where they nest,

The pivotal temperature is around 21°C. There is

needed for Tuatara to survive is approximately

such as laying eggs deeper in the soil. There

less than 1°C separating the production of males

within the range of 4 –15°C in winter and

is a possibility that they will be able to adapt,

and females. Scientists at Victoria University

10 – 25°C in summer.

however as the temperatures are rising so

have found that when incubated at 22°C, 80%

quickly they may not have time.

of the hatchlings produced were likely to be

Tuatara have survived climate changes in the

females. At 20°C, 80% of the hatchlings were

past however these have been at a slower rate,

likely to be females.

this would have given the Tuatara more time to adapt to the changes. Current patterns of 80% Female

global warming could increase the male bias already present in the Tuatara population. Male biased sex ratios are already evident in natural populations of Tuatara, and global warming may further skew sex ratios towards males. Already

21°C 80% Male

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Predators

Kiore Rats Effect on Tuatara

The three species of rat introduced to New Zealand are the Kiore, the Norway and the Ship Rat. Rats impact Tuatara by competing with Kiore Rat

them for food, eating Tuatara eggs, juveniles and even adult Tuatara. They are nocturnal and therefore hunt when Tuatara are most active.

The Tuatara defence strategies of staying still, relying on their camouflage, or retreating to their

Competition for Food and Resources

Predation

burrows are not effective because the rats can sniff them out.

Differences in physical and physiological conditions among Tuatara populations are consistent with Kiore having a detrimental effect upon Tuatara. The presence of Kiore is associated with lower body conditions of adult Tuatara. Evidence suggests that the Kiore may have been nest robbers, taking eggs as well as small hatchlings. As Tuatara are slow breeders they cannot make up for losses.

Adult Tuatara

– Stress Impairs reproduction – Lower body condition

Tuatara Hatchlings and Juveniles

– Less young in population, aging population – Reduced population size

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Evidence of Rat Impact

Percentage of Juvenile and Young Adult Tuatara Present in Sampled Population

In 1981 the rat-free Island Whenuakura near Whangamata, had a population of about 200 Tuatara. In 1984 the Tuatara were wiped out and in their place were Norway rats.

Rat-free Islands MAX

79%

Additional surveys during the 1960s–1980s have supported observations that on rat-inhabited islands, Tuatara have much lower populations.

22%

MIN

Juvenile and small-adult Tuatara have been found on all rat-free islands where more than ten

Kiore-inhabited Islands

Tuatara were found, collectively accounting for 22–79% of the sampled population. In contrast,

MAX

15%

on four Kiore-inhabited islands (all in the Hen and Chickens group), juveniles and small adults have

MIN

0%

rarely been seen, accounting for 0–15% of the 0%

% of Total population

100%

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Current Solutions In recent years the management of captive Tuatara has played a crucial role in enabling the recovery of Tuatara populations, aiding conservation related research, and founding new wild populations as well as raising public awareness of these issues. sampled population.

of age they are used to populate new islands.

Captive Breeding Program

or more females for conservation efforts.

Eradication of mammals

The Objectives of Captive breeding are aimed to

After the young Tuatara hatch they become part

Of all the introduced mammals rats are proving

of the Head Start programme . They are kept

to be the most harmful to the survival of the

in enclosures, in semi-natural conditions for up

Tuatara. Rats have a huge impact on Tuatara by

to five years. The young Tuatara have a higher

competing with them for food, as well as preying

survival rate than in the wild because they are

on eggs, juveniles and even adult Tuatara.

1. Preserve the genetic diversity of all the existing wild populations.

2. Restore Tuatara as part of healthy ecosystem.

4. Promote public knowledge of tuatara and to advocate for their conservation and promote public awareness through accessibility.

3. Obtain new knowledge of tuatara through research.

safe from predators. When they reach 5+ years The Department of Conservation has been eradicating rats from Tuatara islands and their

allow scientists and conservationists to:

surrounding islands to prevent rats swimming

Artificial incubation is part of the captive

from near by islands. Ten island populations of

breeding program. It prevents the loss of laid

Tuatara became extinct during the twentieth

eggs from disturbance by other nesting female

century and rats were present with each of

Tuatara and predation of rats and beetle larvae. It

these. However conservation efforts by DOC

also makes it possible to produces hatchlings as

have seen at lest 13 islands become rat-free in

early as 6 months due to decreased fluctuation in temperature and humidity. The sex ratio of hatchlings can be controlled so that it is possible to produce hatchlings of with the sex ratio 1:1,

Poor Knights group (5 islands) Hen & Chickens group (5 islands) Little Barrier Island

16 Tiritiri Matangi island Cuvier Island Mercury group (4 islands) Alderman group (4 islands) Karewa Island Plate Island Moutoki Island Moutohora Island

Translocation Translocation is the only method by which Tuatara can be restored to parts of their former range. This is one of the one of the only ways to increases their species security.

Sphenodon Guntheri is present naturally on one small island with a Tuatara population of

Takapourewa Island

approximately 400. In 1995, 50 juvenile and 18

Trios group (3 islands)

adult Brothers Island Tuatara were moved to

Titi Island

Titi Island, and their establishment monitored.

North Brother Island

Within five years the translocated population had

Matiu/Somes Island

increased substantially in mass and length.

The Northern Tuatara (Sphenodon punctatus)

A mainland release of S. Punctatus occurred in

Occurs naturally

2005 at the heavily fenced and monitored Karori

Translocated population

Sanctuary. The second mainland release took

The Brothers Island Tuatara (S. guntheri)

place in October 2007 when a further 130 were transferred from Stephens Island to the Karori

Occurs naturally

Sanctuary. In early 2009 the first recorded wild

Translocated population

born offspring were observed.

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The Case of Little Barrier Island (Hauturu) Little Barrier Island (Hauturu) in the Hauraki

Surveys in 1991–92 found eight surviving adult

Gulf, is one of New Zealand’s most valuable

Tuatara, which were caught and housed away

nature reserves. The island is a protected nature

from the rats. These eventually bred, producing

reserve, where human impacts are kept to a

42 eggs, which were incubated at Victoria

minimum and extreme care is taken to keep the

University and the young were raised in rat-free

island free of introduced animals and plants.

enclosures. Kiore were eradicated from the

Little Barrier is one of the last remnants of

island in 2004. In 2006 the first of more than

primeval New Zealand; the only large forested

100 young tuatara were set free. The release of

area left in the country relatively undisturbed by

Tuatara is a major achievement in the ecological

browsing mammals. As such, it is an invaluable

restoration of New Zealand’s nature reserve.

Location of Little Barrier Island

refuge for rare and endangered plants, birds and animals whose mainland habitats have been destroyed. Little Barrier Island is one of the few islands with the potential to support a population of many thousands of Tuatara.

In 1991 no Tuatara had been seen there for 14

Little Barrier Island Hauraki Gulf

years, but the Kiore were thriving. Tuatara were feared extinct from the largest island (3,000 hectares) on which they had previously lived.

Auckland city

Grace Aitken 07023774