Koala (Phascolarctos cinereus): Facts, Diet and Habitat

What does a koala look like?

The koala has a stout, almost tailless body, a large round head, fluffy rounded ears and a big, dark, leathery nose. Its thick woolly fur is gray to brownish gray on the back and paler, almost white, on the chest and belly. The rump is speckled, which helps the animal sit comfortably on rough branches. Koala back fur is among the best insulating coats of any marsupial and sheds rain well.

The hands and feet are built for climbing. Each front paw has two digits that work against the other three, a bit like two thumbs, so the koala can grip narrow branches. On the hind feet, the second and third toes are joined together and used as a grooming comb. All the digits carry long, curved claws.

Koalas also have fingerprints that look remarkably like human fingerprints, with loops and whorls. This is a case of convergent evolution: koalas and primates developed similar ridges independently, probably to grip branches and feel food.

Males are larger than females and have a bare, dark scent gland in the middle of the chest. They rub this gland on tree trunks to leave their scent.

How big is a koala?

Koala size changes a lot across the range. Koalas in Victoria and the south are bigger, with thicker brown-gray fur, while those in Queensland are smaller, lighter and silver-gray.

Males can be up to about 50% heavier than females in the same area. Some researchers once split koalas into three subspecies (Queensland, New South Wales and Victorian), but genetic studies show a gradual change in size and fur from north to south rather than clear groups.

Habitat and range

Wild koalas live only in Australia. Their range covers about 1 million km² (390,000 sq mi) of the east and southeast, from northern Queensland through New South Wales, the Australian Capital Territory and Victoria into South Australia. Koalas had all but disappeared from South Australia by the early 1900s; today’s populations there, including those on Kangaroo Island and in the Mount Lofty Ranges near Adelaide, descend from animals brought in from Victoria.

The key requirement is eucalyptus. Koalas live in tall, open eucalyptus forests and woodlands, from coastal plains to hills and inland river corridors. In dry inland areas they cling to the trees along creeks, where leaves stay moister in drought. Many also live in suburbs and farmland where enough of the right trees remain.

Each adult has a home range it uses for years. Ranges are small where food trees are dense, often just a few hectares, and much larger in poor or sparse woodland.

What do koalas eat?

Koalas are herbivores that feed almost only on eucalyptus leaves. Australia has hundreds of eucalyptus species, but koalas strongly prefer a few dozen, and the koalas in any one area usually rely on just a handful of local favorites. Now and then they also browse other native trees, such as some paperbarks and wattles.

Eucalyptus leaves are tough, low in nutrients and full of oily, toxic compounds. Koalas cope with this with special enzymes in the liver that break down the toxins, gut microbes that help ferment the fiber, and a very long caecum (a side pouch of the gut) of up to about 2 m (6.6 ft). An adult eats roughly 200–400 g (7–14 oz) of leaves a day, sniffing each branch to choose the most nutritious and least toxic.

Koalas get most of their water from the leaves, so they drink less than many mammals. For a full guide to their menu, see what do koalas eat?

Behavior and daily life

Koalas are quiet, solitary and mostly active at night and around dusk. Because their food gives so little energy, they sleep or rest for about 18–22 hours a day, usually wedged into a fork of a tree. Their metabolic rate is roughly half that of a typical mammal of their size. Read more in why do koalas sleep so much?

On hot days koalas move low down on the trunk and press their bellies against the cooler bark. A 2014 study using heat cameras showed that this “tree hugging” helps them shed body heat. They come down to the ground only to move between trees, walking or bounding on all fours.

Koalas spend only a few minutes a day interacting with each other. Adults live in loose groups whose home ranges overlap. Dominant males occupy ranges close to several females.

The most striking koala behavior is the male’s bellow, a deep, rasping call made of snore-like inhalations and belch-like exhalations. It is far lower than expected for an animal of this size. In 2013 researchers found that koalas have a special pair of vocal folds outside the voice box, in the soft palate, which makes these very low sounds possible. Bellows advertise a male’s size and position to females and rivals, especially during the breeding season.

Reproduction and joeys

Koalas breed in the Australian spring and summer, roughly from October to May. After a pregnancy of only about 33–35 days, the female gives birth to a single tiny, hairless joey, weighing under 1 g (0.04 oz) and about the size of a jelly bean. Twins are rare.

The newborn crawls into its mother’s pouch and attaches to one of her two teats. The pouch has a strong ring of muscle at the opening that keeps the joey from falling out. The young koala grows inside for about six to seven months, first poking its head out at around six months old.

Before the joey starts eating leaves, the mother produces a soft, runny form of droppings called pap. The joey eats this, taking in the gut microbes it needs to digest eucalyptus. After leaving the pouch, it rides on its mother’s back and is fully weaned at about one year. Females can breed from about two to three years old, while males usually wait until about four, when they are large enough to compete.

How long do koalas live?

Wild koalas usually live about 10–18 years, with females often outliving males, whose lives are more risky because of fights and roaming. In zoos and wildlife parks koalas sometimes reach 20 years or more.

Old age in koalas is closely tied to their teeth. Years of grinding tough leaves wear the cheek teeth down, and a koala with worn-out teeth can no longer chew enough food.

Predators and threats

Healthy adult koalas have few natural predators. Dingoes, large pythons and powerful owls or eagles may take some, especially young animals. The main dangers today come from people and disease:

• Habitat loss and fragmentation. Land clearing for farming, housing and roads has removed or cut up much of the koala’s former habitat, especially in Queensland and New South Wales.
• Bushfires and drought. Koalas move slowly and climb higher when fire comes, which leaves them exposed in the crowns of flammable eucalyptus. The 2019–2020 “Black Summer” fires killed or displaced tens of thousands.
• Dogs and cars. In suburbs and farmland, dog attacks and road collisions kill thousands of koalas each year.
• Disease. Chlamydia, a bacterial infection, causes eye disease, bladder infections and infertility in many mainland populations. Koala retrovirus (KoRV) weakens the immune system.
• Climate change. Hotter, drier conditions reduce leaf moisture and quality and raise the risk of heat stress.

Conservation status

The IUCN Red List classifies the koala as Vulnerable, with a decreasing population. It was rated Least Concern until a reassessment in the 2010s moved it up because of falling numbers.

National listings are stricter in the north. In February 2022 the Australian government listed the koala populations of Queensland, New South Wales and the Australian Capital Territory as Endangered, after steep declines. Southern populations in Victoria and South Australia are in better shape, and in a few places, such as parts of Victoria, koalas are so numerous that they overbrowse their food trees.

Counting koalas is hard, so population estimates vary a lot depending on method. See are koalas endangered? for the full picture.

Myths and facts

Myth: koalas are bears. Koalas are marsupials. The “koala bear” name was given by early European settlers. Their closest relatives are the common wombat and the two hairy-nosed wombats. See are koalas bears?

Myth: eucalyptus makes koalas “drunk” or “stoned”. Koalas are sleepy because their food provides little energy and takes a long time to digest, not because the leaves act as a drug.

Myth: koalas never drink. They drink rarely, but wild koalas do drink, especially in heat waves and droughts.

The “drop bear”. Australians sometimes joke to visitors about “drop bears”, fierce koalas that fall on people from trees. It is a tall tale with no basis in fact.

Koalas and people

Aboriginal Australians have known the koala for tens of thousands of years, and it appears in many traditional stories. The word “koala” is usually traced to the Dharug language of the Sydney region.

After European settlement, koalas were hunted on a huge scale for their soft fur. Millions of pelts were exported between the 1880s and late 1920s, until public outrage brought full legal protection. Today the koala is, alongside the red kangaroo, one of the best-known symbols of Australia and a major draw for visitors.

Because koalas need large amounts of fresh eucalyptus, only a small number of zoos outside Australia keep them, among them several in Europe and North America, as well as in Japan.