Reptiles heading for extinction

Scientists have identified 20 species of Australian snakes and lizards they predict are at highest risk of extinction; 11, they say, are likely to disappear in the next two decades unless action is taken to protect them.

Reptiles are declining at alarming rates all over the world, says Hayley Geyle from Charles Darwin University, lead author of a paper involving a large team of reptile experts published in the journal Pacific Conservation Biology.

This is particularly concerning for Australia, which is home to 10% of the world’s species – more than any other country. It is a “hotspot for reptile diversity”, Geyle and colleagues write, and more than 90% aren’t found anywhere else.

The Australian government has pledged to avoid more extinctions, they say, but it’s impossible to protect species that aren’t monitored. Less than half have been assessed by the International Union for Conservation of Nature (IUCN), and many assessments are out of date.

The IUCN may even be an insensitive way to identify species at most risk, the authors note, as the categories don’t distinguish between declining and small populations.

“While the IUCN Red List has been instrumental for establishing global conservation priorities, it is not designed to distinguish species on a rapid trajectory towards extinction from those with very small populations that may persist for long periods,” they write.

To fill in some gaps, the team identified 60 Australian terrestrial squamates (snakes and lizards) listed as being of high concern on the IUCN and used experts to estimate their level of threat.

Map of top 20 reptiles credit threatened species recovery hub
Credit: Threatened Species Recovery Hub

Gathering all available information on the ecology, threats and population trends for each species, they sent it to 26 reptile experts across the country and asked them to estimate each species’ probability of extinction by 2040, using the information as a guide and assuming continuation of current management practices.

They found that five of the nine species they added to those on the IUCN threatened list were in the top 10 deemed as most endangered. Thus, many of the detected at-risk species are currently not protected.

Top of the list, with 93% probability of extinction, is Victoria’s grassland earless dragon (Tympanocryptis pinguicolla). The Fassifern blind snake (Anilios insperatus) and three skink species in Queensland are also at greater than 50% risk, along with the Bathurst grassland earless dragon (Tympanocryptis mccartneyi) in NSW.

Queensland is home to more than half the imperilled species, including geckos, sliders and dragons, all with small distributions over less than 20 square kilometres – which is concerning, says Geyle. “This means that each species could be lost to a single catastrophic event, such as a large bushfire.”

Indeed, the authors note that their assessment was completed before Australia’s most recent bushfires, which could have had severe impacts on vulnerable species.

That aside, key threats include introduced species such as weeds and cats, disease, climate change and habitat loss or interference through agriculture, urbanisation, altered fire regimes and mining.

Reptiles have vital roles in ecosystems as predators, prey, seed dispersers, pollinators, habitat modification and pest control. But unlike mammals and birds, relatively little attention has been given to their conservation, partly because they are poorly known and hard to survey.

The Christmas Island forest skink (Emoia nativitatis), for example, disappeared in the wild before being given conservation status, and the few that were captive died not long after being listed as critically endangered.

There is hope, however, Geyle says. “Most threats can be ameliorated, and the very restricted distributions of most species means that we should be able to implement targeted and effective recovery efforts.”

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