By Abbas Nazil
Australia is facing a growing conservation paradox as koala populations surge dangerously in some regions while declining sharply in others.
In parts of southern Australia, particularly on French Island in Victoria and the Mount Lofty Ranges in South Australia, koalas have become so numerous that food shortages now threaten their survival.
On French Island, eucalyptus trees have been stripped bare, with reports of starving koalas falling from trees and multiple animals crowding single gums.
Koalas were introduced to the island in the 1880s to protect the species from extinction caused by commercial hunting.
With no natural predators and limited disease, the population expanded rapidly over decades.
Today, that success has created a serious ecological imbalance.
Nationally, Australia is estimated to have between 729,000 and 918,000 koalas, according to the CSIRO’s latest monitoring program.
While the figures appear higher than earlier estimates, scientists stress this reflects improved survey methods rather than a genuine population boom.
In the Mount Lofty Ranges, which hold about 10 percent of Australia’s koalas, conditions such as rainfall, temperature and soil quality have allowed the animals to thrive.
Researchers warn the population has now grown beyond sustainable levels.
A study published in *Ecology and Evolution* projects growth of up to 25 percent over the next 25 years.
Experts caution that overbrowsing is damaging eucalyptus trees, increasing the risk of widespread starvation.
Many overabundant populations exist in areas where koalas are not native, making local trees less resilient to heavy feeding pressure.
The problem is intensified by the animals’ selective diet, as koalas feed on fewer than 50 of more than 800 eucalyptus species.
Preferred trees such as manna gum and blue gum often grow in monocultures, enabling unusually dense populations.
Commercial blue gum plantations have further boosted numbers, with tens of thousands of koalas displaced when trees are harvested.
Meanwhile, in eastern Australia the situation is far more severe.
Koalas in Queensland, New South Wales and the Australian Capital Territory have been listed as endangered since 2022.
There, populations continue to decline due to land clearing, urban expansion, habitat fragmentation, disease, vehicle strikes and dog attacks.
Nearly two million hectares of suitable koala habitat have been destroyed since 2011, most of it in Queensland.
Scientists agree habitat loss remains the single greatest threat to the species.
Climate change is compounding pressures through droughts, heat stress and increasingly intense bushfires.
Managing overabundant populations presents no easy solution.
Culling is prohibited and socially unacceptable, while relocation is costly and often unsuccessful.
Fertility control through sterilisation or contraception has been used for decades but requires long-term commitment.
Modelling suggests sterilising around 22 percent of adult females annually in high-density areas could stabilise populations.
However, koalas can live up to 15 years, meaning results take time.
Conservationists say both extremes of decline and overpopulation stem from the same issue.
Restoring large, connected landscapes of mixed forest is seen as the most sustainable long-term solution.
With climate projections indicating southern Australia may become the species’ future stronghold, experts say finding a balance is urgent.
Without coordinated national action, Australia risks losing its most iconic marsupial in some regions while watching it starve in others.
