'Whodunnit', as Aussie reptiles go extinct: study

[TOKYO] Three species of reptile on Christmas Island in Australia have been declared extinct in the wild, according to a study released on Tuesday, with scientists baffled as to the cause.

Lister's gecko, the blue-tailed skink and the Christmas Island forest-skink were downgraded from "critically endangered" to "extinct in the wild" in the International Union for the Conservation of Nature's (IUCN) latest report.

"The extinctions ... are an intriguing 'whodunnit', as their cause remains unclear," said John Woinarski, professor of conservation biology at Charles Darwin University in northern Australia.

Populations of reptiles on Christmas Island, an Australian territory just south of Indonesia, have been declining rapidly since the 1970s, the IUCN said.

While scientists speculate that a snake introduced in the 1980s or changes in the environment following the introduction of the Yellow Crazy Ant could be to blame, "the reason for the decline remains unclear," according to the study.

Scientists tried in vain to establish a captive breeding programme for the forest skink and it has now been declared extinct in the wild.

Lister's gecko and blue-tailed skink both have "well-established" captive breeding populations but are now also extinct in the wild.

"In this case, the extent and severity of decline was revealed too late to save these Christmas Island reptiles," said Woinarski.

The IUCN also sounded the alarm over the western ringtail possum, which was downgraded from vulnerable to critically endangered due to a fall in species numbers by 80 percent over the past 10 years.

Scientists suspect climate change is to blame as the possum is "susceptible to heat stress" and its food source has shrunk.

"A drying climate is pushing the ringtail possum to the brink of extinction," said the report.

However, there was better news for two species of kiwi in New Zealand that were upgraded from endangered to vulnerable due to conservation efforts and predator control.

The IUCN's updated "red list" of endangered species was released on Tuesday in Tokyo.

AFP