It’s 2am and Grandpa Boofhead is feeling frisky, his bellows echoing through the moonlit eucalyptus trees around my house in the Adelaide Hills, South Australia. It’s early spring, the breeding season, and those calls will carry for kilometres.
Grandpa Boofhead – the name given to him by my children – is the southern koala type. All koalas are the same species (Phascolarctos cinereus) but he’s twice the size of his northern cousins, sporting darker, shaggier fur.
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We met Grandpa Boofhead in 2007, when we moved into his neck of the woods. We regularly see him, usually at night, ambling between trees. He bellows now from his favourite perch, metres away from our bedroom window, signalling his readiness to mate.
Things can get a little rowdy when his girlfriends, Elvira and Bunny, add their voices to the chorus. Our fondness for our wild neighbour is echoed far and wide.
The koala is beloved not only in Australia but around the world, generating billions of dollars in tourism revenue. You’d think, then, that its future would be secure.
But today, the koala is both endangered and overabundant. It’s a paradox that makes conservation far from straightforward.
Humans and koalas
Humanity’s relationship with this endearing marsupial has had a chequered history. Koalas were once widespread across the bush-clad length of eastern and south-eastern Australia – from Queensland down to Victoria and west into South Australia – perfectly adapted to a life of munching eucalyptus leaves in coastal forests.
That is, until the 19th century, when fur traders arrived. Entrepreneurs spotted the potential offered by koalas’ warm, waterproof pelts and the slaughter began. Eight million skins had been exported by the time public outcry stopped the trade in 1927.
Those that survived might have gone the way of the Tasmanian tiger, which went extinct in 1936, had it not been for the establishment of sanctuaries. These included the Koala Park Sanctuary, Sydney, in 1930, and Lone Pine Koala Sanctuary, Brisbane, in 1927, still in operation today.
Wild island colonies were also founded, with mixed results. The colony on Phillip Island, Victoria, had collapsed by the 1940s, while those on French Island, also off Victoria, and on Kangaroo Island, off South Australia, had significant success.
On French Island in particular, three released individuals enjoyed each other’s company so much that a ‘joey boom’ was soon doubling the population every three to four years. The resulting overbrowsing prompted translocations to ease the strain.
Translocation would become a common intervention in the decades that followed, with thousands of koalas moved from island to island, and to the mainland. Indeed, Grandpa Boofhead’s ancestors arrived in the Adelaide Hills from Kangaroo Island in the 1960s and 1970s.
Koalas: an endangered species?
Yet bouncing back from the fur trade was never going to be easy, particularly as koalas face numerous other challenges. These include habitat loss, with their coastal forest home increasingly cleared for agriculture and development, as well as dog attacks, traffic collisions and diseases such as chlamydia.
Population estimates vary wildly, with the highest around 520,000, while some experts suggest there may be as few as 60,000. The uncertainty further underscores the complexity of koala conservation.
The past 25 years have seen populations plummet by 62 per cent in New South Wales (and the Australian Capital Territory) and by 50 per cent in Queensland.
Both states now list koalas as Endangered, with the species predicted to go functionally extinct in New South Wales by 2050. “As habitat is lost, many are forced to live in increasingly smaller and more isolated pockets with limited access to partners outside their groups,” says Lyndal Hulse of the University of Queensland.
Koalas in South Australia and Victoria may be faring better. In some locations, overabundance has even been recorded, which leads to overbrowsing and, sometimes, mass starvation.
Yet scientists are still in disagreement. Some argue that southern koalas, despite appearing abundant, remain at risk because of their fragmented habitat and narrow gene pool.
Others believe that these populations are thriving compared to their northern counterparts, which have more genetic diversity but higher rates of disease.
Koala conservation, it seems, is a highly emotive issue, where everybody has an opinion and there is never enough money. About 80 per cent of Australia’s koalas live on private land, in backyards, farms and pastures.
Tracking koalas
While Grandpa Boofhead lives out his days in and around our bush block (a patch of natural bushland), not all koalas have it so easy.
In Atherton, northern Queensland, a tropical koala known as Athy was found clinging to a telegraph pole. He had apparently become lost while seeking new territory and was rescued by Roger Martin and Amy Shima from the local Tree-Kangaroo & Mammal Group.
After a health check and a satellite-tag fitting, Athy was released among the eucalyptus of Bluff Forest Reserve, 20km away.
Koalas depend on eucalyptus leaves, known colloquially as gum leaves. These are toxic to most animals but koalas have specialised digestive enzymes that break down the poisons. Their fussy eating habits also help, as some gum species are more toxic than others.
Fingerprints for sensitivity, like those of humans, and a highly attuned sense of smell allow them to select the best leaves. It’s been a long evolutionary road.
Such a low-energy, low-protein diet means that koalas must eat 5-10 per cent (200-1,000g) of their body weight per day, depending on their size and the season (in spring, for instance, leaves are softer, more moist and more nutritious).
Athy feeds for three to four hours a day and sleeps for up to 20, with most of his energy diverted to detoxifying and absorbing his meals. Little wonder koalas have extra backside padding for snoozing in tree forks. They are probably the only mammal that sits down more than we do.
Roger and Amy have been tracking Athy’s movements using a thermal drone and I’ve been invited along. It’s a crisp evening in early September and the rising moon adds a faint glow to the 30m-tall gum trees. A short drive down a track brings us to a quiet spot, where the only noises are the rustling of leaves and the occasional possum call.
The drone buzzes into the gloom, its blinking red lights revealing its path as it ‘mows the lawn’. We are glued to the pilot’s screen, looking for glowing bodies. And while we spot plenty of radiant possums and kangaroos, Athy eludes us tonight.
Fast forward to 4am, 1,750km south, and Sean FitzGibbon and Amber Gillett, from the Koala Ecology Group at the University of Queensland, are on a similar survey in Burbank, a Brisbane suburb that has lost most of its koalas over the past 30 years.
“Drones are a game-changer,” says Sean. “We used to stretch out in a line, walk through the habitat and get sore necks. You’d get your eye in, but you don’t spot them all.”
Once a koala is spotted, it is ‘flagged’ down using a plastic bag attached to a pole, which coaxes a descent. “Seven out of 10 times, this works,” says Sean.
The koala will be measured and given a health check, and may have a radio-collar fitted before being released. Wild koalas are usually placid, according to Amber, but let you know when they’re cross.
“I almost lost two fingers once,” she says. “Koalas have some serious teeth.”
Koalas breed from spring to summer’s end, from September to February – a little earlier for Athy in the north, a little later for Grandpa Boofhead in the south. They are usually solitary and, while females tend to stay within their home ranges, the males cover huge distances in search of mates. Athy himself was tracked travelling 100km during the breeding season.
Females select mates based on bellow quality, and one joey is produced each year. Breeding is a time of renewal but also of vulnerability.
Saving Australia's koalas
Many koalas moving tree-to-tree succumb to dog attacks and car strikes, particularly in urban areas where habitat fragmentation forces them to leave the safety of the canopy.
Then there’s chlamydia, a sexually transmitted bacterial disease, which likely jumped to koalas from livestock. It’s a different strain to the one found in humans and affects up to 90 per cent of koalas in some wild colonies.
Severe cases can be fatal, and thousands of koalas have died, particularly in New South Wales and Queensland, where the immune system-suppressing koala retrovirus is also rife. Treatment is complicated because antibiotics can upset the gut bacteria that koalas rely on.
Thankfully a new vaccine has been developed. Amber has been using it on her Burbank koalas and full rollout is expected next year. Yet a vaccine alone is not enough, particularly as climate change brings more frequent and intense bushfires.
When the flames come – huge, fierce and fast-moving – they rapidly devastate koala habitat. The animals usually respond by staying put in the canopy, a hard-wired instinct that worked when populations were in the millions and losses could be absorbed – but not today.
One such blaze ripped through Victoria’s Budj Bim National Park in early 2025, leaving hundreds of koalas dead or seriously injured. There had been a drought, so the animals were already weak and food was scarce.
The much-publicised cull of injured koalas that followed, with around 700 shot from the air, was described by James Todd, the state government’s chief biodiversity officer, as “necessary euthanasia”.
Researchers expect koala ranges to shrink to the south and east with climate change. But others are more hopeful, and work is afoot by organisations across the country to protect and reconnect koala habitat.
Protecting a national icon
Plans are underway for a 476,000ha nature reserve in New South Wales, dubbed the Great Koala National Park, and a project was launched in 2021 by the Australian Koala Foundation to link fragmented habitat via a 2,543km-long ‘koala camino’ from Cairns in north Queensland to Melbourne in Victoria.
“It’s a long-term vision,” says CEO Diane Tabart. “But these connections could be key to saving the koala.”
Meanwhile, Koala Conservation Australia, in partnership with Taronga Conservation Society, is breeding disease-free animals to boost wild populations in New South Wales and the mid-north coast, with the first joeys born in May 2025. The hope is that these healthy ‘founder’ koalas will breed in the wild.
Given that the range of the koala is more than one million km² – four times the size of the UK – saving this charismatic marsupial cannot be achieved by conservation programmes alone. Community involvement is critical – and Australians, it seems, feel strongly about protecting their national icon.
“There’s an appetite out there,” says Bill Ellis of the University of Queensland. After he gave a talk to farmers at a national farming forum, he was met with a queue of 400 farmers wanting to know how to restore koalas to their properties.
As I listen to Grandpa Boofhead calling into the night, I hope his grandchildren will meet mine among these same gum trees and the future of his species can be secured. Koalas may be vulnerable but they are also tough and adaptable. A land down under with no koalas would be a sad place indeed.
