A koala mother and her joey (young) rest in a eucalyptus tree. Eucalyptus leaves and shoots make up the main part of a koala’s diet.
© Shutterstock

It’s summer in Australia, so you know what that means—time for a koala count! The Australian government has funded a project to count the population of the beloved teddy-bearlike mammals, as well as record where the marsupials (pouched mammals) live. The government commissioned this project because, in recent years, estimates of the koala population have varied greatly. In 2016, for instance, there were an estimated 300,000 koalas in Australia. Three years later, that number was down to 80,000, with some scientists saying the number was as low as 43,000.

In previous counts, people merely counted how many koalas they saw. But, koalas spend almost all their time in eucalyptus trees, making it difficult for people to spot them among the leaves. For the new count, humans will still venture into the forests to search for koalas. But, to ensure a koala-ty count, the government has also introduced some new methods. It will employ heat-seeking drones. A drone is an aircraft designed to operate without a pilot on board. The drones will detect the body heat that a koala gives off. The government will also use dropping-detection dogs—that is, dogs that identify koala droppings. The droppings serve as evidence that koalas live in the area. In addition to detecting droppings, these dogs can sniff out koalas themselves.

In recent years, the koala population has declined. People have cut down eucalyptus forests for housing developments, resorts, and farmland. In addition to spending most of their time in the forks of eucalyptus trees, koalas eat mainly the leaves and young shoots of eucalyptuses. They even get most of the water they need from eucalyptus leaves. Koalas are also vulnerable to natural disasters. Tens of thousands of koalas were killed when bushfires devastated large areas of Australia in late 2019 and early 2020. In fact, a study by the World Wildlife Fund (WWF) estimated that more than 60,000 koalas had been either killed, injured, or displaced by the fires. This staggering number led some scientists to say that the animal was “functionally extinct.”

There are efforts to increase the koala population in Australia. For instance, the WWF hopes to use drones to drop eucalyptus-tree seeds in forests. The WWF will also create a fund to sponsor koala sanctuaries (safe spaces).

December 23, 2019

Saturday, December 21, was the winter solstice in the United States and the rest of the Northern Hemisphere. In the Southern Hemisphere—which includes Australia, New Zealand, and other lands south of the equator—the solstice marks the beginning of summer. In Australia, summer is a season known for bushfires. Such wildfires are common in Australia, due in part to the country’s hot and dry climate. Many wildfires start in the remote countryside known to Australians as the bush. Bushfires can be extremely destructive, especially if they reach urban areas. The fires often kill people and destroy property and farmland. They also devastate forests, along with the koalas and other animals that live there.

Police in Jimboomba, Queensland, rescued this koala and her joey from a bushfire in late November 2019. Many other koalas were not so lucky. Credit: Jimboomba Police

A number of major bushfires have plagued Australia in 2019. Late last summer, in February, bushfires consumed more than 50,000 acres (20,000 hectares) of land in northern New South Wales. Far more destructive bushfires ignited again in New South Wales in September, burning nearly 5 million acres (2 million hectares) there and in neighboring Queensland. Some of those fires lasted for weeks, while others continue to burn, turning skies black or orange, causing severe damage, and killing a number of people. The bushfires also killed thousands of vulnerable and slow-moving koalas trapped by the rapidly spreading flames.

Bushfires are relatively common in Australia. These fire-damaged buildings are seen alongside a house that survived Christmas Day bushfires near Melbourne in 2015. Credit: © Julian Smith, EPA/Landov

Koalas live only in the forests of Queensland, New South Wales, and Victoria, in eastern Australia. They are found in significant numbers in only a few areas, and the animals are protected by law. Bushfires, however, ravage the koala’s natural habitat and its population. Koalas cannot escape the fast-moving fires, and their only defense is to climb to the top of a tree, curl into a ball, and hope the flames do not rise to reach them. Koalas sometimes survive this way, but they often burn their paws and claws descending charred trees, leaving them unable to climb properly again.

Koalas are not officially listed as endangered, but the population in New South Wales and Queensland has decreased by more than 40 percent since 1990. The animals are threatened by deforestation and habitat loss, as well as the effects of climate change, which is causing longer and more intense heat waves and droughts, leading to more frequent, intense, and longer-lasting bushfires. Beyond the flames and smoke of the fires, many koalas die from lack of water or exposure to prolonged periods of high temperatures. Australia just suffered through the driest spring in its history, and a brutal heat wave peaked on Dec. 19, 2019, when the highest ever nationwide average temperature—107.4 °F (41.9 °C)—was recorded.

October 31, 2014

Hopes for the survival of Australia’s wild koalas have been boosted by test results for a new vaccine against chlamydia, a disease that is ravaging populations of the beloved marsupial. One of vaccine’s developers told news media that the sexually transmitted disease, which causes blindness and infertility, is one of the “tipping points” contributing to the decline of the species. Estimates of the current size of the koala population vary from several hundred thousand to as few as 43,000. Conservationists estimate that the animal’s numbers in New South Wales and Queensland have fallen by as much as 40 percent since 1990. In 2012, the government of Australia, for the first time, listed koalas as a vulnerable species in the states of New South Wales and Queensland and in the Australia Capital Territory. Other threats facing koalas include habitat loss, wild and domestic dogs, urban development, mining, and climate change.

For the trial, researchers captured  60 wild koalas and fitted them with radio collars so the animals’ movements could be tracked. They then vaccinated 30 of the koalas. Some of these koalas were healthy; some were infected by chlamydia; some had already developed symptoms of the disease. The researchers found that none of the vaccinated koalas developed the disease. In addition, those animals already infected did not go on to develop chlamydia. And nearly all of those that had symptoms improved. Among the nonvaccinated group, more of the koalas became infected and the condition of animals with chlamydia worsened.

A female koala carries her joey (young) on her back. Wild koala populations have fallen because of the bacterial infection chlamydia. Scientists are working on a vaccine to prevent and treat the infection in koalas.  (Dave Watts, Tom Stack & Associates)

The researchers plan to continue their tests for another year. If results remain positive, wild koalas could be vaccinated for their protection. “We hope to specifically show a positive effect of the vaccination disease, not just infection, as well as female reproduction rates,” one of the researchers said.

Additional World Book articles:

• Endangered species

May 3, 2012

The government of Australia has, for the first time, listed koalas as a vulnerable species in the states of New South Wales and Queensland and in the Australia Capital Territory. Australia’s federal government lists threatened species in three categories: vulnerable, endangered, and critically endangered. The vulnerable classification means that governments in the three areas must take koala populations into account when evaluating applications by developers.

A female koala carries her joey (young) on her back. The joey spends its first seven months in the mother's pouch and the next six riding on her back. (Dave Watts, Tom Stack & Associates)

Conservationists welcomed the listing as a significant benefit in protecting koala populations from threats ranging from habitat loss and urban development to mining and climate change. They noted, however, that the listing does not protect koalas in certain areas being logged in New South Wales. Conservations also argued that the declaration should have been national in scope.

Estimates of the current size of the koala population vary from several hundred thousand to as few as 43,000. Conservationists estimate that the animal’s numbers in New South Wales and Queensland have fallen by as much as 40 percent since 1990. Native to Australia, koalas are marsupials whose diet consists of the leaves of the eucalyptus tree. They can sleep up to 20 hours a day.

Additional World Book articles:

• Conservation
• Wildlife conservation
• History of Attempts to Save Species (a special report)
• Threatened Species Around the World (a special report)