Koala

The koala is a marsupial endemic to Australia, meaning it is found in the wild nowhere else on Earth. Despite the common nickname 'koala bear,' it is not a bear at all; its closest living relatives are wombats, and like all marsupials it raises its young in a pouch. Koalas inhabit eucalyptus forests and woodlands stretching from northern Queensland down through New South Wales and into Victoria and South Australia. They are highly arboreal, spending almost the entire day and night in trees, where they rest, feed and sleep for up to 18–20 hours a day to conserve the limited energy their leaf diet provides. Individuals occupy overlapping home ranges centred on favoured food trees, and densities vary enormously between regions, from healthy southern populations to severely depleted northern ones.

Few animals are as specialised as the koala. It feeds almost exclusively on eucalyptus leaves, which are tough, low in nutrients and laced with toxins that would sicken most mammals. Koalas cope through a long digestive tract and a large caecum full of microbes that ferment and detoxify the foliage, plus a slow metabolism and long rest periods. They select around 30 preferred eucalyptus species out of more than 600, and local populations often specialise on whichever species grow nearby. Their cheek teeth are adapted to shear and grind fibrous leaves, and they obtain most of their water from foliage, though they will drink during heatwaves and drought. This deep reliance on specific trees is also their greatest vulnerability: when those trees are cleared or burned, koalas have little ability to switch foods or move elsewhere.

Koala declines are driven by a stack of overlapping pressures. The clearing and fragmentation of eucalyptus woodland for agriculture, forestry and urban growth removes the trees koalas depend on and forces them to cross roads and open ground, where vehicle strikes and dog attacks take a heavy toll. Disease is a major factor in many populations, particularly chlamydia, which can cause blindness, infertility and death, and koala retrovirus, which weakens the immune system. Drought and extreme heat add further stress, and catastrophic bushfires, such as those of the 2019–2020 fire season, killed or displaced large numbers of koalas and destroyed vast areas of habitat. Northern populations in Queensland and New South Wales have fallen sharply, which is why those populations were uplisted to Endangered under Australian federal law in 2022, even though the species globally remains classified as Vulnerable.

Protecting and reconnecting eucalyptus habitat is the single most important action for koala survival. Conservation efforts focus on safeguarding remaining forest, restoring corridors between fragmented patches, planting preferred food trees, reducing land clearing, and managing threats such as roads, dogs and disease. Wildlife hospitals and carers rehabilitate sick, burned and injured koalas, while research into chlamydia vaccines and population monitoring aims to slow disease spread and track recovery. Because the koala depends so completely on intact, connected woodland, habitat protection delivers the broadest long-term benefit, sheltering not only koalas but the many other species that share Australia's eucalyptus ecosystems.