Silent extinctions occurring unreported across Australia – from spiders to frogs

Creatures are quietly going extinct in Australia before anyone can describe and name them.

Australia recognises 67 of its fauna species including the Tasmanian tiger are extinct, but animal experts believe the number is much higher.

It’s assumed two frogs that haven’t been seen since the 1990s and an elusive snake have been wiped out even though on paper they're listed as critically endangered.

When it comes to insects and spiders the situation is worse, as it’s believed many have fallen victim to a phenomenon called “silent extinction”. This term refers to a species vanishing from existence before scientists can describe and name it.

This is the first of a two part series investigating the gap between declared versus actual extinctions.

A Tasmanian tiger in colour (left) and a mountain mist frog (right) on a leaf.
The Tasmanian tiger (left) is declared extinct, but the mountain mist frog (right) is still listed as critically endangered. Source: NFSA/Stephen Richards

🐸 Which frogs are most likely extinct?

Queensland’s mountain mist frog (Litoria nyakalensis) will likely be uplisted from critically endangered to extinct on Australia’s Environment Protection and Biodiversity Conservation (EPBC) list of threatened species. It hasn’t been seen since April 1990 – a year after several frog species in the Wet Tropics were decimated by an outbreak of chytrid fungus – and it has already been declared extinct on the international Red List.

James Cook University’s Professor Conrad Hoskin spent 25 years searching rivers for the species in vain.

“Another frog that's essentially lived the same story is the northern tinker frog (Taudactylus rheophilus). They declined dramatically after 1990, and some individuals persisted until around the year 2000, but they dropped out just after that,” he said. “We are essentially certain those two species are extinct.”

Hoskin also fears a critically endangered reptile's days are numbered — the Fassifern blind snake (Anilios insperatus). “That species hasn’t been seen for decades now,” he said.

A creek running through the Wet Tropics.
One of the last known places the mountain mist frog was recorded. Source: Professor Conrad Hoskin

😶‍🌫️ Are species ever rediscovered?

The process for declaring extinction is slow because there is little funding to search for surviving populations of rare creatures.

Occasionally species are rediscovered, as was the case with two small lizards last year – the Victorian grassland earless dragon which hadn’t been seen since 1969, and the Lyon’s grassland striped skink which was last documented in 1981.

We have these sort of silent extinctions, these species that we don't even know anything about. They don't have a name. We don't know they exist. And they may already be gone.Dr Jeremy Wilson

🕸️ Are spiders facing extinction?

Although Australia is internationally renowned for its colourful spiders, few are protected under state or federal conservation laws. And just 2700 of an estimated 10,000 spider species are thought to been described.

“You've got species that are known from three or four records, there are lots that haven’t been seen in over 100 years. But often that's just because nobody's gone out and looked,” spider expert Dr Jeremy Wilson explained.

The process of describing and in turn protecting spiders is slow and museum shelves are stacked with dozens of specimens waiting to be examined — less than 10 scientists in the country have sufficient taxonomic expertise in spiders to identify new species. Wilson is one of them and he splits his time between the University of Western Australia, the Western Australian Museum and Queensland Museum.

He was involved in describing the trapdoor spider (Euoplos dignitas) which like many spider species is confined to a small, heavily fragmented habitat, and this puts them at risk of being wiped out by events like land clearing or extreme weather. “We don’t have the data to know the damage we’re doing. With vertebrates the ranges are much larger, and so it's a little harder to completely destroy a range. But with some invertebrate species it's completely possible,” he said.

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🔎 How do we know we are losing species?

Although there is little data in Australia about insect extinctions, Dr Nick Porch, an archaeologist at Melbourne’s Deakin University has examined fossil records on Mauritius, Hawaii and French Polynesia to better understand the impact of human arrival on fauna. He found evidence of widespread extinctions due to the lifestyle needs of the new inhabitants.

“They burn wood to cook. They cut down forests to grow their plants. They get rid of habitat and that means extinctions through loss of places these species live,” he said.

“If you apply that to the Australian context, we know we've lost lots of habitat because large parts of Australia have been cleared for agriculture. We know that forestry has had an impact on species. But the problem in our part of the world is we really don't understand very well the abundance and the spatial distribution and even the diversity of the invertebrates that we have.

“With the invertebrates here I could go out this afternoon and find new species if I went to the right place. The abundance and diversity of these things is so incredible, and what that means is it's really hard to say, with any sort of certainty, the extent of extinctions in these groups, other than to suggest that it's clearly happening.”

More on extinction

🦤 Extinction rate too high

Environment non-profit the Australian Conservation Foundation notes that some degree of extinction is a normal and actually essential for evolution to occur, but the current rate is thousands of times higher than what’s natural. Its nature campaigner Peta Bulling is warning reported extinctions are “just the tip of the iceberg”.

Climate change, invasive species and the bulldozing of forests are driving a silent extinction catastrophe. Australia needs strong political action to protect our unique nature or the numbers will continue to grow,” Bulling said.

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