Using Innovation to Create Safe Habitat

Extinct in the Wild for over a decade, the bright Blue-tailed skink and Lister’s gecko are ready to return home.

Home to lush rainforests and unique flora and flora, 63% of Christmas Island is a National Park. More than a mere homecoming, this project will use innovative technology and research to make their habitat safe and sound by suppressing their main predator, the Wolf snake.

Join us as we embark on a mission to reclaim safe habitat for these small endemic reptiles on Christmas Island.

The story

: A Lister’s gecko is perched on the edge of a rock, all of its toes gripping onto the surface. It is approximately 5cm from head to vent, a yellow-fawn colour with black spots, and golden yellow eyes.

Lister’s Gecko. Photo: Jason Turl.

Prior to 1979 there were five recorded species of endemic terrestrial reptiles on Christmas Island, and one native non-endemic skink.

Today, only two species remain in the wild, the Giant Gecko (Cyrtodactylus sadleiri) and the Christmas Island blind snake (Ramphotyphlops exoccoeti). They are highly threatened.

Two of the six species are extinct on Christmas Island: the endemic forest skink (Emoia nativatis) and the coastal skink (Emoia atrocostata).

The remaining two species Lister’s gecko (Lepidodactylus listeri) and the Blue-tailed skink (Cryptoblepharus egeriae) are considered Extinct in the Wild. Luckily, thanks to one intrepid Parks ranger and a whole team of supporters, they’ve been secured in ex-situ populations and are now ready to be released back into the Christmas Island ecosystem.

The threat

Wolf Snakes (Lycodon aulicus capucinus), an introduced invasive species, are the prime suspects behind the significant decline in native reptile populations on Christmas Island. The evidence indicates that their spread across the island closely aligns with the patterns of lizard disappearances.

But, worldwide, it’s unknown how to stop invasive reptiles in their tracks. The research and on-ground work behind suppressing and eradicating invasive reptiles is lacking. Rangers, research institutions, and community on Christmas Island will be navigating largely uncharted territory. However, they’ll have the backing of conservationists and specialists around the world!

Another challenge is that the behaviours and habits of the Wolf Snakes on Christmas Island are largely unknown, adding to the difficulty behind tracking, trapping, and removing them – and the need for research and innovative approaches.

Wolf Snake strangling a Lister's Gecko

Wolf Snake predating on a Lister’s Gecko Photo: Parks Australia.

Facing the challenge with research and innovation

No species are universally distributed. They show unique patterns of distribution based on their available environments. Understanding how an invasive species interacts with its habitat to complete its life cycle is the key behind effective suppression strategies.

Environmental DNA (eDNA) testing means only a drop of water is needed to track a source, making tracking invasive species much more efficient.

Environmental DNA (eDNA) testing means only a drop of water is needed to track a source, making tracking invasive species much more efficient. Photo: Department of Environment – Photographer, DCCEEW Production team.

To gain this understanding, Parks rangers are using new eDNA technology to help unveil the mysteries around the Wolf Snake’s movements on Christmas Island so that they can be tracked down and trapped.

Teaming up with eDNA technology specialists CESAR Pty Ltd, Parks staff have mapped the Wolf Snake’s genome, enabling tracking through eDNA sampling. Further, eDNA field collection protocols have been developed and trialled on Christmas Island, promising new research into the Wolf Snake’s habits and behaviours in that environment.

Comprehensive research in partnership with research institutions, will inform Park rangers of snake pheromone biochemistry, and once that is understood, Pheromones will be used to lure the love-lust snakes into the traps during breeding season.

In partnership with Christmas Island National Parks Reptile Advisory Group and in collaboration with rangers, specialists, and researchers around the world, suppression methods will be formed, and research outcomes shared to inform global conservation efforts.

The Return Home

Parks Australia maintains captive breeding programs for both Lister’s gecko and the Blue-tailed skink, in which genetic diversity is carefully managed.

A subset of the species from various ex-situ populations across the Cocos Keeling Islands, Christmas Island enclosures, and Taronga Zoo will be released to areas on Christmas Island when wolf snakes are suppressed to a level where they no longer pose a threat. This would effectively re-establish wild populations of these two species in their native habitat and restore their role within the Christmas Island ecosystem.

Biosecurity ensuring a lasting impact

The biosecurity on Christmas Island is managed by State and Federal governments, with every arrival to the island assessed by Australian Quarantine and Inspection Service staff. With in-principle support for continuous biosecurity enhancements, the likelihood of a new Wolf snake incursion on the island is very low, strengthening the long-lasting legacy of his project.

More information

Taking advantage from one of the pilot research projects in which the total genome of the wolf snake has been determined will greatly improve the efficiency of using eDNA for the distributional information. 

If you’re interested in reading the most recent published research regarding the collapse of a native reptile population, see the paper by Jon-Paul Emery et al. 

Jon-Paul Emery, Nicola J. Mitchell, Harold Cogger, Jessica Agius, Paul Andrew, Sophie Arnall, Tanya Detto, Don A. Driscoll, Samantha Flakus, Peter Green, Peter Harlow, Michael McFadden, Caitlyn Pink, Kent Retallick, Karrie Rose, Matthew Sleeth, Brendan Tiernan, Leonie E. Valentine, John Z. Woinarski , 2021, The lost lizards of Christmas Island: A retrospective assessment of factors driving the collapse of a native reptile community’, Conservation Science and Practice published by Wiley Periodicals LLC. on behalf of Society for Conservation Biology.

Your support will back the cutting-edge technology and research needed to suppress the invasive Wolf snake, ensuring the survival of threatened reptiles on the island.

Help bring back the Lister’s gecko and Blue-tailed skink to their native habitat, and form a vital contribution to conservation research and action worldwide.

Join us in creating a secure haven for Extinct in the Wild species to return to their native habitat on Christmas Island.

A Blue-tailed skink looking outwards from atop a small rock. Its bright blue tail is curled towards the camera.
Blue-tailed skink. Photo: Parks Australia

The extinction risk is very real, so habitat preservation is vital.

The time to act is now.

Support the Lister's Gecko
Ensure this gecko is not lost forever!
Support the Blue-Tailed Skink
Get the Blue-Tailed skink home!
Quell the Wolf Snake
Support research to stop the Wolf Snake!
All donations within Australia (over $2) are tax deductible.
Image credits:
Header: Blue-tailed skink, © Parks Australia.
Line breaker: Hosnies Springs, Christmas Island© Photographer – Michael Mahony.
Tiles L-R: Lister’s Gecko, © Jason Turl; Blue-tailed Skink, © Parks Australia; Wolf Snake, © Parks Australia.


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