Koala Paradox: Thriving in Some Regions, Facing Extinction in Others
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Koala populations across Australia are exhibiting a startling dichotomy: while facing decline and endangerment in the north and east, numbers are booming to unsustainable levels in the south, creating a complex conservation challenge.
Australia’s beloved koala is facing a crisis of abundance in some areas even as it teeters on the brink of extinction in others. Recent data reveals a national koala population estimated between 729,000 and 918,000, a significant increase from previous estimates. Though, experts caution that this rise is largely attributable to improved survey technology rather than a genuine population surge. The core issue remains a fragmented and precarious future for the species, with localized overpopulation creating new threats to their long-term survival.
A Tale of Two populations
The most dramatic example of this paradox is unfolding on French Island in Victoria’s Western Port Bay, where koalas are literally falling from trees, victims of starvation due to overbrowsing. Eucalypts have been stripped bare by the burgeoning marsupial population, with reports of koalas found dead or severely malnourished. This situation mirrors a similar crisis in South Australia’s Mount Lofty Ranges, where the koala population – representing roughly 10% of the national total – is experiencing rapid growth.
“The ranges tick all the right boxes,” explains Dr. Frédérik Saltré, a senior lecturer in ecology at the University of technology Sydney. “Rainfall, temperature, soil acidity really boosted the habitat suitability… so they could actually thrive in this ecosystem.” A recent study co-authored by Saltré, published in Ecology and Evolution, projects a 17% to 25% increase i
further north, the situation is drastically different. Koalas in queensland,New South wales,and the Australian Capital Territory have been officially listed as endangered since 2022. Here, populations are dwindling due to widespread habitat loss from land clearing and urban growth, coupled with the impacts of disease, vehicle strikes, and dog attacks.
“By far the biggest issue is habitat loss,” asserts Assoc. Prof. Desley Whisson, a terrestrial wildlife ecologist at Deakin University. Climate change, with its associated droughts and increased fire frequency, is also accelerating the decline. Analysis reveals that nearly 2 million hectares of suitable koala habitat have been destroyed since the species was declared threatened in 2011, with 81% of this clearing occurring in Queensland.
While the southern states grapple with overabundance,Whisson notes that,aside from specific locations like islands and the Mount Lofty Ranges,koala populations are generally at low densities across much of the country. “I’m actually a bit concerned that we might be losing some of our populations,” she says, adding that the overabundance issue overshadows the broader, more insidious threat of decline.
Difficult Solutions and a Long-Term Game
Addressing koala overabundance presents a significant challenge. Translocation – moving koalas to new areas – is expensive and not always accomplished. Culling is politically unfeasible given the koala’s iconic status. Fertility control, involving sterilization or long-term contraception, offers a more palatable solution, but it is indeed a slow process.
New modeling by Saltré suggests that sterilizing approximately 22% of adult females annually in the highest-density areas of the Mount Lofty Ranges could stabilize populations at sustainable levels, at an estimated cost of $34 million over 25 years. “It is indeed a more cost-effective strategy than translocation, but concedes “we’re playing the long game here, which is usually way [beyond] the political timeline.”
Ultimately, a holistic approach focused on landscape-scale habitat restoration is crucial. The recent creation of the Great koala National Park in New South Wales, with a moratorium on logging, is a positive step. In the southern states, creating larger expanses of mixed forests – less conducive to high koala densities – is essential. As Saltré concludes, “we need to find a sweet spot where the species can be sustainable over a long time.”
