The future survival of Koalas threatened with extinction in Australia may come down to an isolated population on an island off the continent’s mainland, experts say.
A group of 50,000 Chlamydia-free ‘bears’ offers an insurance policy against the species being wiped out completely by the various threats they face.
They include habitat loss from deforestation, diseases such as chlamydia, attacks from predators, fire and road collisions are all contributing to their decline.
Conservationists in Australia recently reported that Koalas in the country are already ‘functionally extinct’.
This describes an animal population which is either so small it has ceased to affect its environment or has no breeding pairs left.
If the species is still breeding, but from such a small number of individuals that it succumbs to genetic disease, it may still be counted as functionally extinct.
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The future survival of Koalas threatened with extinction in Australia may come down to an isolated population on an island off the continent’s mainland, experts say (stock image)
Scientists led by the University of Adelaide have discovered that, unlike every other large population in Australia, Kangaroo Island koalas are free from infection by Chlamydia pecorum.
This bacterial infection is the most significant disease causing death in koalas, and a key factor in koalas being under threat in north-eastern Australia.
‘The impact of Chlamydia on populations of koalas in Queensland and New South Wales is devastating, with high levels of severe disease and death, and common infertility,’ says researcher Jessica Fabijan, PhD candidate with the University of Adelaide’s school of animal and veterinary sciences.
‘This last large, isolated Chlamydia-free population holds significant importance as insurance for the future of the species. We may need our Kangaroo Island koalas to re-populate other declining populations.’
For the study, researchers captured and released 75 wild koalas from the Mount Lofty Ranges and 170 koalas from Kangaroo Island (KI).
Each koala was checked by a veterinarian and tested for Chlamydia pecorum and koala retrovirus.
On KI, historical veterinary records of koalas were searched for incidence of chlamydial disease.
There were over 13,000 records collected over 22 years by the South Australian Department for Environment and Water (DEW).
Researchers found that 46.7 per cent of koalas from the Mount Lofty Ranges were positive for Chlamydia, although the vast majority not showing signs of disease.
All KI koalas tested negatively for Chlamydia and no disease was observed.
There were no definitive cases of chlamydial disease in the 13,000 past records of koala examinations on KI.
A group of 50,000 Chlamydia-free ‘bears’ offers an insurance policy against the species being wiped out completely by the various threats they face (stock image)
Research is now underway to understand the difference in Chlamydial disease severity between southern and northern koalas.
‘This is a very important finding because Chlamydial disease is so prevalent and efforts to fight it have so far been unsuccessful,’ added project leader Dr Natasha Speight, also from the University of Adelaide’s school of animal and veterinary sciences.
‘Although, South Australian and Victorian koala populations are stable, this is believed to be at least partly due to current lower prevalence and severity of Chlamydial disease.’
KI’s population is one of the few, and likely the largest, Chlamydia-free population of koalas in Australia.
And Koala numbers have fallen so low across Australia that the species is now ‘functionally extinct’, animal campaigners believe.
Risks to Koalas include habitat loss from deforestation, diseases such as chlamydia, attacks from predators, fire and road collisions are all contributing to their decline (stock image)
The Australian Koala Foundation said there may be as few as 80,000 of the animals left in the wild, meaning they are unlikely to produce a new generation.
The foundation says that, since 2010, it has monitored 128 Federal electorates that fall within known koala environments, and in 41 there are no koalas left.
While researchers admit that the koala’s tendency to move around and its patchwork habitat make it difficult to track, they say numbers are in steep decline.
Between 1890 and 1927, more than eight million of the animals were shipped to London after being shot for fur.
Research conducted in 2016 showed there were around 330,000 of the animals left in Australia, though this number could be as low as 144,000 and as high as 600,000.
The biggest threats to koalas are habitat loss and heatwaves caused by climate change, such as the one last year that saw thousands of animals die from dehydration, studies have shown.
The full findings of the study were published in the journal Nature Scientific Reports.
Scientists led by the University of Adelaide discovered that, unlike every other large population in Australia, Kangaroo Island koalas are free from infection by Chlamydia pecorum
