Unique koala group thought to be extinct faces new threat

Michael Dahlstrom
·News and Video Producer
·5-min read

There are calls to better protect a tiny koala colony whose complex genetics could be critical to the marsupial’s survival across southern Australia.

While "sightings" of extinct Tasmanian tigers always come to nothing, these unique koalas defied the odds and actually survived a wave of hunting and clearing.

The small but largely unknown population of endemic koalas, once believed wiped out across mainland Victoria, were found in fragmented habitat in the 1990s, living in South Gippsland, Victoria.

While visually similar to Victoria’s other populations, scientists are increasingly realising the Strzelecki koalas have special qualities not found elsewhere.

Their genetic complexity will likely allow them to better adapt to future pressures like extreme weather and disease.

Researchers believe Strzelecki koalas need to be given better protection. Source: Suzie Zent
Researchers believe Strzelecki koalas need to be given better protection. Source: Susie Zent

Describing their miraculous survival as “gorillas in the mist type stuff”, veteran koala researcher Dr Stephen Phillips believes they should be given increased government protection.

“They’ve got so much to contribute to the conservation of Victorian koalas, but it really needs to be recognised and managed very, very carefully,” Dr Phillips said.

“It can't be managed like your typical Victorian koala.”

Why most of Victoria's koalas are vulnerable

Strzelecki koalas, named after the range in which they live, were noticed in the 1990s by researchers investigating health implications resulting from inbreeding, a complication likely to affect nearly all koalas in the southern states.

Genetic bottlenecks occurred when the species was pushed to extinction across mainland Victoria and South Australia, and then later repopulated using just a handful of surviving animals on French Island and Phillip Island.

As expected, most koalas analysed suffered from a weak gene pool, and this has been found to lead to kidney and renal failures, undescended testicles and high levels of hermaphroditism.

There are concerns many of these animals could suffer a sudden population decline like the Tasmanian devil did, another species affected by a historical genetic bottleneck.

Between 1996 and 2015, 95 per cent of devil populations infected by cancerous facial tumours were wiped out and the high mortality could be linked to lack of diversity in their immune genes.

Put simply, if a population's genes are similar, either all or none of the animals are likely to be impacted by a disease, and this can wipe out large numbers very quickly.

Scientists believe genetic bottlenecks made Tasmanian devils more susceptible to population declines due to disease. Source: Getty
Scientists believe genetic bottlenecks made Tasmanian devils more susceptible to population declines due to disease. Source: Getty

What excited the researchers about the Strzelecki koala tissue samples is that they were from animals who were genetically complex – as unlike other populations in Victoria they have not been translocated.

This endemic population have even found a way to live with chlamydia, a disease that has decimated koalas in NSW and Queensland.

Large numbers of Strzelecki koalas living on timber plantation

While the Strzelecki koalas survived 'extinction' last century, their future is now less than certain.

Environmentalists have singled out bushfire and habitat loss as the greatest threats to their fragmented populations.

Their range was significantly impacted by Black Saturday over a decade years ago and many believe they were lucky to avoid Black Summer last year.

Despite their importance, Victoria's department of environment (DELWP) said they were unable to provide an estimate of how many Strzelecki koalas remain.

They directed population questions to a private company, HVP Plantations, where a significant number of Strzelecki koalas are believed to survive on their landholdings.

Despite their significance the Victorian government do not know how many Strzelecki koalas remain. Source: Getty
Despite their significance the Victorian government do not know how many Strzelecki koalas remain. Source: Getty

Building a critical picture of koalas on their land has proved difficult as, despite providing a link to their detailed koala management plan, the company declined to answer any direct questions about Strzelecki koalas from Yahoo News Australia.

In a statement, a company spokesperson highlighted their work to protect koalas, which has included safeguarding forest from logging as well as investment in ongoing research.

“HVP has a close affinity with koalas and responsibly shares its workplace with this iconic animal,” a spokesperson said in a statement.

“HVP has a comprehensive koala management plan to help maintain its Victorian population.”

The company acquired the land following a privatisation drive by the Kennett government in the 1990s which saw the animals' habitat leave state hands, frustrating environmentalists.

Friends of the Earth, who have campaigned to get stronger protections for Strzelecki koalas, say competing with commercial interests has complicated work to safeguard them.

Despite division between environmentalists and the timber company over logging practices, in recent years both camps have privately reported ongoing cooperation around the issue of koala protection.

Difficult pathway to protection for distinct koalas

What originally appeared to be one significant group has since been identified as two distinct populations of genetically complex animals, thanks to ongoing research by Federation University’s Faye Wedrowicz.

The populations have been identified by DELWP as potentially having a “greater ability” to adapt to like climate change.

A Strzelecki koala in care after losing his mother. Source: Susie Zent
A Strzelecki koala in care after losing his mother. Source: Susie Zent

Rising carbon dioxide levels are likely to affect the nutritional quality of the koala’s food source, eucalyptus leaves, however Strzelecki koalas could have the genetic diversity to adapt.

Some effort is being made to preserve their genetics, with DELWP safeguarding the population with a translocation exclusion zone so they cannot breed with the state’s other more abundant koalas.

The Federal Environment Minister likely has the clearest pathway to protect the animal further, by listing the Strezlecki koala as a vulnerable animal via the Environment Protection and Biodiversity Conservation (EPBC) Act.

According to the department, the legislation allows a “distinct population of biological entities” to be classified as a species, but a spokesperson said it is “used sparingly” like in the case of the NSW, ACT and Queensland koalas.

They said their focus is on supporting the recovery of these nationally-listed koala populations and that an assessment of Victoria’s overall koala population in 2012 found it to be “large and relatively stable”.

While the Commonwealth has committed $1 million to build a genome sequencing program for koalas, they are not currently considering listing the Strzelecki koala as a threatened species.

For now, the Strzelecki koalas, despite their significance, remain vulnerable and in need of further research.

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