Species’ expansion threatens South Australia’s habitat and biodiversity, Lisa Cox
Last modified on Fri 12 Jul 2019 22.55 AEST
A sterilisation program of Kangaroo Island koalas had little success, a report says Photograph: Alamy
Animals including koalas and kangaroos could be culled in parts of South Australia, where high population numbers are damaging the landscape.
A report from a parliamentary inquiry has recommended the state’s environment minister make an immediate decision to declare koalas, western grey kangaroos, long-nosed fur seals and little corellas overabundant in some areas.
Culling is an option that could be suggested, although the report acknowledges there is reluctance to communicate publicly the need for culling because “some community stakeholders find the concept of culling an abhorrent approach in managing overabundant species”.
The inquiry, by the parliament’s natural resources committee, investigated the impact and management of certain overabundant and pest animals and the effectiveness of current measures to keep numbers under control.
If the recommendation is adopted to declare population numbers of certain species too high, it would trigger ministerial powers to order control options.
In relation to koalas, the committee took evidence from Kangaroo Island’s natural resource management board urging culling of populations on the island.
“The board is concerned that the koala population will continue to increase to a point where irreparable habitat damage occurs,” the report said.
The overabundance of several species was caused by changes to the landscape
The committee heard that sterilisation of the Kangaroo Island koala population had had little success.
“Population numbers on the Island continue to rise and their impacts are threatening its biodiversity,” the report says.
Little corellas were identified through the inquiry as a species requiring statewide management because the species “has become so prolific that isolated management actions are ineffective”.
In the case of long-nosed fur seals, the committee heard that the species was affecting the Coorong fishery.
But the report says culling is only one of several options that could be considered and there were numerous tools that would not involve culling such as habitat modification and acoustic repellent devices.
In the committee’s report, the presiding member, Josh Teague, said overabundant species were causing an “imminent threat” to wildlife and habitats.
“The overabundance of several species was caused by changes to the landscape, including by the clearing of native vegetation,” he said.
“Further, the committee heard that unless we act to manage the problem by culling abundant animals, there will not be a lot of other biodiversity in the state.”
with Australian Associated Press
Kangaroo Island koalas touted as species saviours after showing no signs of chlamydia – ABC
2 July 2019
Less than a decade ago, the number of koalas on Kangaroo Island was so high they were being sterilised in large numbers in an attempt to bring the population under control.
- Koala populations in Queensland and New South Wales have been decimated by chlamydia
- But koalas on Kangaroo Island have shown no sign of the disease, researchers say
- That population is now regarded as crucial for the survival of the species
Now, however, the island off mainland South Australia is being touted as a potential lifeline for koala populations across Australia, particularly the eastern states.
The island’s koalas could be the last in the country that are entirely free of chlamydia, Adelaide researchers say.
The bacterial infection is widespread in koalas in Queensland and New South Wales and has had devastating effects, causing blindness, infertility and death.
“This last large, isolated chlamydia-free population holds significant importance as insurance for the future of the species,” University of Adelaide PhD candidate Jessica Fabijan said.
“We may need our Kangaroo Island koalas to repopulate other declining populations.”
In recent years, koala numbers have been decimated in north-eastern Australia because of high levels of disease and death.
A new study by the team involved capturing and testing 245 koalas — 170 from Kangaroo Island, 75 from the SA mainland.
While almost 47 per cent of mainland koalas tested positive for chlamydia, none of the Kangaroo Island koalas showed any signs of the disease.
Ms Fabijan is working alongside staff from South Australia’s Department for Environment and Water (DEW) and the University of the Sunshine Coast in an effort to rejuvenate koala numbers across the nation.
Veterinary scientist Natasha Speight, who oversaw the research project, said having a chlamydia-free population of koalas would complement work on a vaccine developed in Queensland.
“Chlamydia is the biggest threat towards koala health,” Dr Speight said.
“Koalas in South Australia are really interesting because we don’t know as much about them as we do in the eastern states.”
“There’s a lot of information we can learn, particularly about their diseases and their health.”
Survival of the species at stake, department says
Unlike the eastern states, South Australia has witnessed an increase in koala numbers in recent years, and the estimated population of koalas on Kangaroo Island is currently about 50,000.
But koalas are not native to the island and were first were introduced in the 1920s as a back-up, because of the effect of hunting on the mainland.
Like the human strain, koala chlamydia is sexually transmitted.
Ms Fabijan said the island’s population had been protected for geographical reasons.
“They’re isolated and they’re chlamydia free,” Ms Fabijan said.
“We don’t know where [the chlamydia] came from, it’s probably been in the population for thousands of years.
“There is a possibility it came from livestock because they share the same species of chlamydia.”
While sterilisation using non-surgical contraceptive implants is ongoing across South Australia, DEW spokesperson Brenton Grear said Kangaroo Island had a vital role in saving the species.
“Future-proofing South Australia’s koala health is paramount to ensuring the survival of the species in Australia, given the marked decline in the eastern states,” he said.