The koala (Phascolarctos cinereus), sometimes called the “koala bear,” is an iconic marsupial endemic to Australia. It lives mostly in eucalyptus trees and feeds primarily on eucalyptus leaves. Because this diet is low in energy and contains plant toxins that are costly to process, koalas conserve energy by resting for long periods and living a slow‑paced arboreal life.
It helps to separate global and regional listings: the IUCN Red List assessment for the koala is Vulnerable (VU; assessed in 2014), while the Australian Government lists koalas as Endangered under federal law in Queensland, New South Wales and the Australian Capital Territory—reflecting higher risk in parts of the eastern range.
Taxonomy and naming
Koalas are marsupials in the family Phascolarctidae and the genus Phascolarctos. Despite the common nickname “koala bear,” they are not bears; they are more closely related to wombats.
Appearance
Koalas have a compact, sturdy body, a large round head, fluffy ears, and a prominent hairless nose. Fur colour ranges from grey to brownish‑grey, often with paler areas on the chest and inner limbs. Strong limbs, sharp claws and grasping hands are well suited to climbing and holding onto tree trunks and branches.
Range and habitat
Koalas are native to eastern and south‑eastern Australia, occurring in Queensland, New South Wales, Victoria and a small part of South Australia. Their habitat is defined by the presence of suitable food trees—typically open eucalypt forests and woodlands. Densities tend to be higher where preferred trees grow on more fertile soils and along watercourses. In some regions, koalas also persist in urban and peri‑urban landscapes where tree cover and connectivity remain.
Behaviour
Koalas are mostly active at night and around dawn and dusk. To conserve energy on a low‑calorie diet, they may sleep or rest for up to about 20 hours a day. They are generally solitary but live within overlapping home‑range networks. During the breeding season, males produce deep bellows to advertise their presence and compete for mating opportunities.
Diet
They feed mainly on eucalyptus leaves, and may also browse a few closely related tree species. Koalas rely on specialised digestion and gut microbes to break down fibrous leaves and handle plant toxins. Much of their water intake comes from leaves, although they may drink during hot or dry conditions.
Reproduction and life history
Females can breed from around two years of age, while males often begin breeding at three to four years. Gestation is short—about 35 days—and usually a single joey is born. The joey develops in the pouch for around six months, then rides on the mother’s back. In the wild, average lifespan is about 10–12 years; females can live as long as ~18 years in favourable conditions, while males are typically shorter‑lived.
Relationship with humans
Koalas are a flagship species for wildlife tourism and conservation education. At the same time, they are vulnerable to vehicle strikes, dog attacks, and habitat fragmentation around growing towns and cities. Rescue and rehabilitation networks are important in many regions.
Conservation status and threats
Major threats include habitat loss and fragmentation, road mortality, dog attacks, disease (notably chlamydia‑related illness), heatwaves and drought, and bushfires. Because pressures differ across the range, koala conservation is often managed regionally: federal endangered listing applies to parts of the eastern range, alongside on‑ground habitat protection and connectivity measures.
