Skinks facing extinction find new hope away from predatory snakes

Endangered blue-tailed skinks released on Cocos (Keeling) Islands after facing extinction In short: More than 500 blue-tailed skinks have been released on Horsburgh Island in the Cocos (Keeling) Islands in an effort to bolster numbers. Numbers of the species dropped dramatically due to introduced predators on Christmas Island. What's next? It is hoped that the blue-tailed skinks will breed and establish a large colony on Horsburgh Island, enabling them to be removed from the critically endangered list. A critically endangered skink almost wiped out by predatory snakes on Christmas Island has been given a new chance of survival after being relocated to a remote island off Western Australia. More than 500 blue-tailed skinks were released on Horsburgh Island in the Cocos (Keeling) Islands, about 2,900 kilometres north-west of Perth, in July, and researchers are hopeful their numbers could increase into the hundreds of thousands. The species was hunted to the brink of extinction due to predators introduced to Christmas Island, mainly the South-east Asian wolf snake. Christmas Island National Park threatened species manager Brendan Tiernan said the snake had devastated lizard populations. "By 2009 there was only one population left on the most remote pocket of Christmas Island, and extinction was imminent," Mr Tiernan said. "We realised that we're about to lose these species and it was time to get out there and secure them into captivity before they fell off the edge of the cliff." Parks Australia's threatened species program coordinator Shayla Stefanetti said despite being only 10 to 12 centimetres long, the absence of the tiny skink had been noticed by island residents. "Locals used to see them everywhere; they were very well described with their bright blue tails," she said. Lizards travel by air When Parks Australia began tracking the lizards, they captured only 66. Those blue-tailed skinks provided the foundation for a successful breeding and conservation program on Christmas Island, and their numbers swelled to around 400. The breeding program enabled staff to translocate the lizards to the neighbouring islands of Pulu Blan and Pulu Blan Madar in the Cocos (Keeling) archipelago in 2019 and 2020, where predators were absent. The lizards were transported by air and sea in special containers. "Those two islands were very successful and reached capacity of around 5,000 animals each," Ms Stefanetti said. Horsburgh Island was chosen as the next translocation site due to its size and similar lack of predators. Fifty times as large as either Pulu Blan or Pulu Blan Madar, Hosburgh Island has the potential to host an even larger population of the species, thereby safeguarding its future. Species milestone Ms Stefanettis said she was hopeful the translocation, led by Parks Australia and Taronga Conservation Society Australia, would be successful. "[We] have the potential to have hundreds of thousands of skinks living on Horsburgh,"she said. "To go from extinct in the wild to then have a really successful population flourishing in the wild, that is huge. "It's a huge milestone for not only the species, but for our national park to achieve as well." Mr Tieran said it was unlikely blue-tailed skinks would be able to be released back onto Christmas Island in the near future. "For the time being, we have no viable control options for the wolf snake, [so] returning them to the wild on Christmas Island isn't an option," he said. "It's certainly something that we're trying to progress towards, [but] snakes are notoriously difficult to control."