6 Jul 2018

Red List update: Australian reptiles in crisis, surprise toad rediscovery

Climate change and invasive species don’t just impact birds – the latest update to the IUCN Red list of threatened species shows that they are a growing threat to Australia’s unique reptiles. However, the update also revealed good news for four South American amphibians assumed to be extinct.

The Carchi Andes Toad was thought to be extinct - until now © Gabriela B. Bittencourt-Silva
By Jessica Law

Our Bird Red List update of 2017 rang alarm bells for invasive species and climate change. Now, the latest findings of the IUCN Red List confirm that the pressures driving avian declines are part of wider problems shared across the natural world. One of the most shocking discoveries is that that 7% of Australia’s reptiles are now threatened with extinction.

Australia’s reptiles are something special. These lizards and snakes evolved in isolation from the rest of the world, radiating out into a varied and fascinating array of species. This diversity is so large that they represent almost a tenth of the world’s reptile species. It’s no wonder they form the keystone of indigenous art and storytelling. Their loss would be a huge blow to science, culture and the ecosystems they support.

Sadly, the risk of this happening is getting higher. For more than half of them, the biggest danger is invasive species: it is estimated that feral cats alone kill about 600 million reptiles a year. One of the biggest victims of this feline bane is the Grassland Earless Dragon Tympanocryptis pinguicolla (which really does lack ears). This year, its status was updated from Vulnerable to Endangered.


The Grassland Earless Dragon is now Endangered due to cats and wildfire © Will Osborne


The grassland specialist’s struggle is exacerbated by loss of habitat. Like many Australian species, this small dragon is adapted to the semi-natural wildfire patterns that were in place prior to European settlement.  Now, agriculture, invasive weeds and the loss of traditional indigenous burning methods leave it with scant refuge.

Not all invasive species are predators. The Cane Toad Rhinella marina, native to South America, was deliberately introduced to Australia in 1935 in an attempt to eradicate the Cane Beetle Dermolepida albohirtum. This blunder has wreaked environmental havoc ever since, with toad’s highly toxic nature poisoning every predator that attempts to eat it. One distressing example is the Mitchell’s Water Monitor Dermolepida albohirtum. Since the Cane Toad arrived, this huge swamp-dwelling lizard has seen population declines of 97% in some areas. This year, it enters the Red List as Critically Endangered.


The Mitchell's Water Monitor has declined by 97% from eating toxic Cane Toads © Stewart Macdonald


As if that wasn’t enough, climate change is a growing concern. The Bartle Frere Cool-skink Techmarscincus jigurru is a cold-adapted lizard found only on the summit of Queensland’s tallest mountain, Mount Bartle Frere. Its name reflects its predicament: just a 1°C increase in temperature is likely to result in a loss of 50% of the Cool-skink’s population within 30 years, as there are no colder areas for the animal to move to.


The Bartle Frere Cool Skink could die out due to a warming habitat. Not cool. © Stewart Macdonald


As bleak as this picture seems, knowledge is power, and can be used to catalyse action.

“This Red List update highlights the vulnerability of Australia’s lizards and snakes to invasive alien species, including the toxic Cane Toad and feral cats, often in combination with threats from habitat loss due to invasive weeds, development, and fire,” says Philip Bowles, IUCN SSC Snake and Lizard Red List Authority Coordinator. “Understanding the threats to each of Australia’s native reptile species will help us effectively work with the Australian Government, local conservation groups and indigenous people to address them.”

Four toads formerly presumed extinct were rediscovered in Colombia and Ecuador

Nature always has the power to surprise us, and no Red list update is complete without some good news. This year, four toads formerly presumed extinct were rediscovered in Colombia and Ecuador. The Rio Pescado Stubfoot Toad Atelopus balios, Quito Stubfoot Toad Atelopus ignescens and an Ecuadorian species Atelopus nanay were all suspected to have succumbed to the deadly chytridiomycosis disease, a fungus which has devastated amphibian populations across the planet. And the Carchi Andes Toad Rhaebo colomai was hit so hard by habitat loss that it was also feared to be gone forever – but it has proven to be a survivor.


The Quito Stubfoot Toad: not as extinct as we thought © Luisa Coloma Centro Jambatu


With this wonderful reprieve comes the opportunity to help these species on the road to recovery.

“[The toads] are still negatively impacted by human-induced threats… highlighting the urgent need to improve the conservation of these species to prevent their extinction,” says Jennifer Luedtke, IUCN SSC Amphibian Red List Authority Coordinator.

So what can we learn in relation to birds? Reptiles and amphibians are (arguably) not as beautiful as their avian cousins, but climate change and habitat loss are no less of a threat. In this way, birds can play a vital role as a popular flagship to rally people under. In saving them, we save the species that share their ecosystem.