Facts

The big koala facts page

Every core claim on this site, in one place, with its source.

What they are

Koalas are marsupials: mammals that give birth to underdeveloped young. Queensland Government: Koala facts They are different enough from other marsupials to be placed in their own family, Phascolarctidae. Queensland Government: Koala facts Their closest living relatives are wombats, and both have a backward-facing pouch. Queensland Government: Koala facts The scientific name is Phascolarctos cinereus: the genus draws on Greek for a pouched ‘bear’, and cinereus is Latin for ashy-grey. Queensland Government: Koala facts The word koala is said to come from a Dharug word meaning ‘no water’ — the Queensland Government presents that as a reported etymology, not a proven one. Queensland Government: Koala facts The Australian Museum gives a size range of 68–82 cm. Australian Museum: Koala

The body

A koala is unmistakable: thick ash-grey fur, a white chest, a round head and fluffy ears. Australian Museum: Koala Koalas in Queensland are smaller, lighter in colour and have less fur than those in New South Wales, Victoria and South Australia. Queensland Government: Koala facts In Queensland, adult females weigh about 5–6 kg on average and adult males about 6–8 kg; in Victoria, average weights are about 8.5 kg for females and 12 kg for males. Queensland Government: Koala facts They have two opposable thumbs on their fore paws, which helps them grip smooth-barked gum trees. Queensland Government: Koala facts Koalas are arboreal — they live in trees — but they do climb down to move between trees, walking slowly on the ground and, if disturbed, bounding at up to about 30 km an hour. Queensland Government: Koala facts A male marks trees and attracts females with a scent gland on his chest, which oozes a strong, musky oil. Queensland Government: Koala facts They have an acute sense of smell, used to detect other koalas and favoured food trees. Queensland Government: Koala facts Koalas can sleep for up to 20 hours a day, because their diet is low in energy and breaking down the toxic leaves takes work. Queensland Government: Koala facts They are mostly active at night, and around dawn and dusk, though they will move in daylight if they are disturbed, too hot or too cold, or need a new tree. Queensland Government: Koala facts

Diet

The diet is highly specialised: mainly the leaves of certain eucalypts, plus some flowers and stems, and a few related trees such as lophostemon, melaleuca and corymbia (brush box, paperbark and bloodwood). Queensland Government: Koala facts The Australian Museum likewise describes a specialised diet of certain eucalypt leaves, with some flowers and stems, and a long caecum to help digest the fibrous leaves. Australian Museum: Koala A koala eats around 500 grams of leaves a day — about the size of a small lettuce. Queensland Government: Koala facts Most of their water comes from the leaves, which can be up to about 50% water, so they often have no need to climb down for a drink — except in very hot or dry periods. Queensland Government: Koala facts The leaves are low in energy, with only about 5% sugars and starches on average, and they contain toxic oils that most animals cannot eat. Queensland Government: Koala facts A specialised gut, including an elongated, coiled caecum, and gut bacteria break the leaves down; joeys are not born with those bacteria. Queensland Government: Koala facts The mother passes those bacteria to the joey in a sticky, runny faecal substance called pap, which the young ingests instinctively. Queensland Government: Koala facts The IUCN assessment also describes a specialist diet, mostly Eucalyptus foliage with occasional leaves of other, mostly myrtaceous, plants. IUCN Red List assessment PDF: Koala (Phascolarctos cinereus)

Life cycle

Males usually begin mating at three to four years old; females can breed from about two, generally having one joey a year for the next 10 to 15 years. Queensland Government: Koala facts Gestation lasts 35 days, after which the mother usually gives birth to a single joey; twins are possible but rare. Queensland Government: Koala facts In Queensland, births usually take place between November and February. Queensland Government: Koala facts The joey stays in the pouch for about six months before emerging, then rides on its mother’s back for between six and 12 months. Queensland Government: Koala facts By about 12 months the young is weaned and takes up a home range that overlaps with its mother’s for much of the next year. Queensland Government: Koala facts The Australian Museum likewise notes six months in the pouch, then a gradual weaning from milk to leaves and pap from the mother. Australian Museum: Koala Breeding season differs between northern and southern populations: in the north, an estimated 60% of births occur in summer and early autumn (December to March). Australian Government conservation advice for the listed koala (in effect 12 February 2022)

Where

The Australian Museum describes a patchy distribution from northern Queensland to southern Victoria and south-eastern South Australia. Australian Museum: Koala The Queensland Government likewise places them across much of Queensland, New South Wales, Victoria and a small area of South Australia, in open forest and woodland where the right food trees grow. Queensland Government: Koala facts The IUCN lists the koala as native and extant in New South Wales, Queensland, South Australia and Victoria. IUCN Red List: Koala (Phascolarctos cinereus) The IUCN notes introductions to at least 12 islands, including Kangaroo Island in South Australia and French and Phillip Islands in Victoria, and a mainland introduction in the Adelaide region. IUCN Red List assessment PDF: Koala (Phascolarctos cinereus) Fossil records show koalas once inhabited parts of Western Australia and the Northern Territory; there are no fossil records of them in Tasmania. Queensland Government: Koala facts Habitat is defined by a select group of food trees; densities are higher on more fertile soils and along watercourses, and they can remain in partly cleared and urban areas. Queensland Government: Koala facts

Status and threats

The IUCN Red List assesses the koala (Phascolarctos cinereus) as Vulnerable globally, under criteria A2b+3bce+4bce. The assessment date is 27 May 2014 (published 2020, and annotated as needing an update). IUCN Red List: Koala (Phascolarctos cinereus) · checked 12 Nov 2026 The IUCN population trend is decreasing, with a global estimate of 100,000–500,000 mature individuals (best estimate 300,000). IUCN Red List: Koala (Phascolarctos cinereus) · checked 12 Nov 2026 The combined koala populations of Queensland, New South Wales and the Australian Capital Territory have been listed as Endangered under Australia’s EPBC Act, in effect from 12 February 2022. Australian Government conservation advice for the listed koala (in effect 12 February 2022) · checked 12 Nov 2026 Other koala populations, in Victoria and South Australia, are not listed as threatened under the EPBC Act. Australian Government conservation advice for the listed koala (in effect 12 February 2022) · checked 12 Nov 2026 CSIRO’s National Koala Monitoring Program 2025 national estimate is between 729,000 and 918,000 koalas. CSIRO cautions that this may reflect increased monitoring effort rather than a substantial rise in numbers. CSIRO: Calling out the koala legends (November 2025) · checked 12 Nov 2026 During the 2019–2020 bushfire season, an estimated 9% (more than 36,800 km²) of the koala’s distribution was impacted by fire, according to the Australian Government conservation advice (citing DAWE 2021a). Australian Government conservation advice for the listed koala (in effect 12 February 2022) · checked 12 Nov 2026 The conservation advice identifies habitat loss from land clearance and mining, climate change (including drought and rising temperatures), disease, and deaths on roads and from dogs among the main threats, which can also act together. Australian Government conservation advice for the listed koala (in effect 12 February 2022) · checked 12 Nov 2026 Chlamydiosis, a bacterial disease, threatens many koala populations. Two forms can infect koalas: Chlamydia pecorum (the most common cause of disease) and Chlamydia pneumoniae. NSW Environment and Heritage: Understanding chlamydia in koalas · checked 12 Nov 2026 The disease can cause infertility, particularly in females, and can lead to blindness, weakness, and greater vulnerability to dogs and extreme weather. NSW Environment and Heritage: Understanding chlamydia in koalas · checked 12 Nov 2026