In the midst of the Anthropocene, natural habitats and the wildlife that occupy them simply cannot seem to catch a break. This is certainly the case in Australia, which exhibits the highest rates of mammal extinctions globally. One of the species contentiously facing extinction in Australia is the iconic Koala (Phascolarctos cinereus). This arboreal marsupial is an endemic species, occupying much of eastern Australia, spanning across Queensland, New South Wales, South Australia and Victoria. The distribution of the Koala aligns with key habitat species from the genera Eucalyptus and Corymbia, found in tall Eucalypt forests and low Eucalypt woodlands. Due to a lack in nutrient availability in these leaves, Koalas need to consume approximately two and half pounds of leaves per day – a significant number in proportion to body size. As Koalas require such high intake of food, it is critical that a large extent of habitat remains available for the species to be able to thrive.
However, unfortunately for the Koala they are no longer considered to be thriving in the Australian landscape, in fact, it has become evident recently that it is quite the opposite. The conservation status of the Koala has been contested, however recently adjusted from ‘Least Concern’ in 2008, to ‘Vulnerable’ in 2014. The IUCN Redlist suggests the number of mature individuals is estimated between 100,000 and 500,000 individuals, with a declining trend in population. The population status of the Koala varies by State and therefore makes assessments of a total conservation status difficult to define. While some populations are becoming locally extinct, others appear to be healthy. Despite this large variation in population estimates, a study in 2016 estimated a national population size of 329,000 individuals, observing a 24% reduction over the last three generations. Although listed as ‘Vulnerable’ to extinction, it is argued that a more updated assessment would see this species upgraded once again to ‘Endangered’, given the current magnitude of threats they are facing.
Like many other species around the globe, the Koala is facing considerable threats to species persistence, particularly in relation to human influences. Since European settlement in Australia, humans have inflicted many negative impacts to Koalas. Throughout the early twentieth century, Koalas were dealt a significant blow by humans as they were widely hunted for their fur and their habitat cleared. Although population numbers were able to bounce back from this, more recent threats of urbanisation, introduced domestic and feral species, disease, motor vehicle collisions and climate change, have all become major threats to the survival of the species. The Australian Koala Foundation estimates that over 4,000 koalas are killed each year by dog attacks and motor vehicle collisions alone. These threats act in unison, making consequences for the species considerably worse. For example, as habitat becomes constricted and individuals need to return to the ground to seek further habitat or more nutrient rich trees, their risk of being attacked or hit by a car increases. In addition, the threat associated with needing to return to the ground, elevates stress and leaves koalas more prone to disease such as Chlamydia.
Despite the array of threats impacting the Koala, the two posing the most serious threat to persistence are habitat loss and climate change. Koalas require approximately 100 trees per individual, an increasing issue as Australian Woodlands continue to shrink. Urban development and land clearance for timber industries and agriculture have significantly reduced the amount of available habitat to the Koala, fragmenting the landscape and leaving populations small and scattered in most cases. The removal of Eucalyptus trees results in an inability to support the species in terms of protection and habitat, but also decimates critical food sources, leaving populations to starve.
To make matters worse for the Aussie icon, climate change is here and Koalas are particularly vulnerable to its impacts. While it is not unusual for the Australian landscape to endure hot temperatures, droughts and wildfire, climate change will bring these events closer together, making them both more frequent and more severe. Although wildfire can cause widespread devastation, much of the Australian vegetation such as Eucalypts actually require fire for regeneration.
Over millions of years species have become adapted to these events – thick insulating bark, dormant buds called epicormic shoots sprouting upon fire damage, and thick woody encapsulated seeds within their canopy that will drop after fire into a thick nutrient rich ash bed. These traits give native species a competitive advantage in the aftermath of the fire, when there is less competition for light and nutrients along the forest floor. Despite these advantages, if fires are too severe or too close together, they become completely incinerated and lack the ability to recover. This is unfortunately what we have observed over late 2019 and early 2020 along the east and south coast of Australia, where over 12,000,000 hectares of land was burned – where the Koala, among many other species is concentrated.
While unprecedented bushfires swept across Queensland, New South Wales, South Australia and Victoria, particular and confronting devastation was observed on Kangaroo Island – South Australia, where at least half of the island was entirely scorched, leaving nothing but ash and burnt carcases behind. The Island was a lush oasis for native species, rich in biodiversity, largely attributed to its removal from the mainland and the ability to keep introduced species such as foxes and rabbits away. The population of Koalas was thriving here, home to approximately 50,000 individuals, one of three known populations entirely free from Chlamydia. Sadly, it has been estimated that half of this population perished in the recent bushfires. Over in New South Wales it has been estimated that 8,000 Koalas have died in the bushfires since September, one third of the total population within the entire State. For Victoria and Queensland losses have been unquantified, although significant breeding grounds and populations have perished in these regions. The losses observed in Queensland, New South Wales and Kangaroo Island are particularly concerning as these populations have the greatest genetic diversity and contain populations free of Chlamydia. Chlamydia is common among Koalas and can be detrimental to breeding success of the species, as if left untreated causes infertility to individuals.
While many species have been impacted by these fires (kangaroos, wallabies, potoroos, cockatoos, honeyeaters), Koalas have been among some of the hardest hit. Amidst fire, the species curls up into a ball, high up in the canopy of a Eucalypt. This behaviour can be effective in moderate fires where flames don’t often reach the canopy, however proves hopeless amongst such severe bushfires. In addition, Koalas are slow moving, the removal of much of their habitat has left the species with nowhere to go in the aftermath of fire and they occupy extremely flammable trees that often burst into flames in such high intensity fires. Severe burns on Koalas digits are particularly concerning as this means there will be no claw. Without a claw, Koalas are unable to scale the trees, therefore will not be able to seek protection or feed. Other injuries that have emerged from the fires include broken bones from falling out of trees, as well as severe dehydration and malnutrition, leading to the shutdown of organs.
As the bushfires began to settle and the real damage to Koalas became evident, the Victorian population was subject to callous acts of animal cruelty. After large extents of habitat were burned throughout Gippsland, a further 140 acres of land was bulldozed on a Victorian blue gum timber plantation near Cape Bridgewater. While the act of cutting down plantation timber is not illegal, there are strict regulations and protocols in place to protect species such as Koalas that may be inhabiting the trees. South West Fibre – the hardwood plantation company – carried out all protocols to ensure a safe operation, discarding any tree containing a Koala from being harvested and leaving all 76 Koalas in good health upon their leaving. A second and illegal logging operation carried out by a landowner however, resulted in deaths, dehydration, starvation and broken bones. Fortunately 80 Koalas were able to be saved, although in dire health, these individuals were taken in by wildlife rescuers. Sadly, 40 individuals were either found dead or needed to be euthanised due to injuries, many still clutching onto branches, crushed between the felled timber.
It is difficult to determine the fate of the Koala – estimates of loss are indeed estimates, and in most cases bodies were unable to be found due to the high intensity of the fires. The biggest concern is now whether or not there is enough habitat for the species to remain viable and be relocated into, only time will tell. Prior to the bushfires, World Wildlife Fund predicted the Koala could be extinct as early as 2050. While it is true that these catastrophic fires may have brought that extinction timeline forward, there is still hope for the Koala. Massive efforts are being made into habitat restoration planning, wildlife breeding populations and research into genetic diversity by many organisations. The Government has also contributed 50 million dollars to a wildlife package, dedicated to ensuring native species survival in the aftermath of fire. Unfortunately areas hard hit by the recent fires aligned with prime Koala habitat, however areas of suitable habitat do remain. It is critical now that this remaining habitat be protected by the Australian government. While Koalas are protected by law, their homes and food are not – why protect a species if we are going to continue to decimate their habitat and food source? Under business as usual it is very likely we may see the Koala go extinct.
Above all else, this disaster has sparked much needed conversations and attention into the climate and biodiversity crisis – both of which are being heavily felt in Australia. More investment is being made into emergency response to wildlife, funding has been poured into animal rescue organisations, and the massive public response around the globe has been overwhelming. Koalas are a charismatic umbrella species, meaning their attention and protection will secure habitat for many other Australian species – a story of hope in an ecological disaster. What we do need to keep in mind though, is that this was only one summer. With projected increases in temperature, longer periods of drought, and more intensive and frequent bushfires, we need to be proactive not reactive in the future. As a society we need to significantly reduce our emissions, demand better environmental protection for our wildlife and their habitats, and demand governments take immediate action on climate change.
Ecosystems and species can recover after natural disasters, however only if they have the resilience to do so – an ability humans have notoriously taken away. Australia can’t afford to lose another species at the cost of economic growth and development, especially not this one.
Koalas have evolved over millions of years to recover after fire, if they can’t bounce back from this, the onus is on us.
