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When the word ‘possum’ is mentioned in Australia, most people might instantly think of a bold and rambunctious brush-tail possum, or perhaps a conspicuous flower-eating ringtail. What most people might not know, is that Australia is home to at least 32 species of possums, and this number is likely to increase with further genetic analyses. In fact, recent DNA testing has revealed that the greater glider and sugar glider are actually three different species each (northern greater glider, central greater glider and southern greater glider, and sugar glider, Krefft’s glider and savanna glider respectively), raising the number of Australian possum species by four in just the last couple of years!
Whilst Australian possums might not have the most creative English names (e.g., striped, brushtail, ringtail, pygmy, short-eared, yellow-bellied, feathertail), fortunately evolution has been more interesting, resulting in a diverse range of appearances, abilities, and ecology within the group. They range in size from the world’s smallest possum, the little pygmy possum at 7-10 g and 50-75 mm long (that’s about as the size of a matchbox car and the weight of 7-10 paper clips!) through to the generously weighted brushtail possum species weighing up to 4500 g, and the greater glider that can measure up to a metre long (that’s including its very long feather boa of a tail)
Having evolved adaptations for living in trees and shrubs, possums are basically Australia’s equivalent to global primates such as monkeys and lemurs. Possums fill similar ecological roles, including seed dispersal, pollination or being prey to predators. Some possums have also evolved similar physical traits to primates, including opposable thumbs, a prehensile tail, and big toes, to help them grasp branches and food. One striking example of convergent evolution between possums and primates is the striped possum, which lives in far northern Queensland, Papua New Guinea and Indonesia, and shares common traits with the disturbingly unique-looking aye-aye lemur of Madagascar. These species are the only known mammals to use ‘percussive foraging’, whereby they tap on parts of trees to find cavities and then use their powerful jaws and a special elongated finger to extract wood-boring larvae.
The gliding ability displayed by more than a third of Australia’s possum species, (thanks to ‘patagia’: skin membranes between the forelimbs and hindlimbs), is arguably their most remarkable physical adaptation, allowing them to efficiently navigate their tree-top environment and evade predators. Australia contains the world’s smallest gliding mammal species, the broad-toed and narrow-toed feathertail glider weighing 13 g (that’s about as heavy as a AAA battery), and the world’s largest gliding marsupial the greater glider which weighs up to 1.5 kg and can glide 100 metres!
Another useful ability displayed by many of Australia’s smaller possums is a process called ‘torpor’, where animals are able to significantly decrease their body temperature and metabolism to conserve energy. This process can occur for a few hours each day for some species and reduces the animal’s need for food, helping them survive unfavourable conditions like extreme dry or cold weather, or fire. Deeper and longer bouts of torpor are described as hibernation, a process observed in mountain, eastern and western pygmy possums. Somewhat counterintuitively, the mountain pygmy possum normally hibernates among rocks and under a snow blanket that protects it from the harsh winter conditions. Unfortunately, these snow blankets are disappearing due to climate change, and along with a reduction in bogong moth prey due to drought, artificial light pollution, and pesticide use, the mountain pygmy possum faces a very real risk of extinction.
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Although many of Australia’s possums are probably unfamiliar to most people, recent media stories have brought attention to the plight of some of the most threatened species including the critically endangered Leadbeater’s possum, mountain pygmy possum, and western ringtail possum, and the endangered greater glider. Many of Australia’s possums are threatened by habitat loss from logging and land clearing for livestock farming and mining, loss of tree hollows, climate change, inappropriate fire regimes, and introduced predators such as foxes and cats. Despite increased awareness among land managers, decision makers, and the public of the threats facing some of Australia’s possum species, manageable threats impacting some species continue unabated.
Australian possums are much more than just brushies and ringtails, and they include a diverse group of animals with some incredible abilities that perform vitally important ecological roles. So, next time someone mentions the word ‘possum’, give a thought to some of the other amazing possum species that call Australia home!
The nominees for preferred possum are:
Southern greater glider (Petauroides volans), the east coast: Queensland, New South Wales, Victoria.
Imagine a cat-sized cross between a possum and a koala that can also basically fly. Greater gliders are the largest marsupial glider in the world, and an important forest indicator species. Often one of the first to drop out of areas that have been disturbed, it’s possible to use this incredible animal to gauge how the ecosystem is going for other forest-dependent critters.
Common ringtail possum (Pseudocheirus peregrinus), eastern Australia and Tasmania.
This endearing species forms enduring family groups, with both parents caring for the young, typically twins: the parents carry their young on their backs. The white-tipped tail is strong and prehensile, useful for carrying nesting material or for balance.
Torresian striped possum (Dactylopsila trivirgata), Queensland and Papua New Guinea.
It has the largest brain for its body size of any marsupial and also has an elongated fourth finger that it uses to extract juicy grubs out of rotting timber – very handy!
Savanna glider (Petaurus ariel), northern Australia: Queensland, Northern Territory, and Western Australia.
A species that managed to fool scientists for a very long time, it was only in 2021 that the savanna glider was formally recognised as being a new and undescribed species.
Leadbeater’s possum (Gymnobelideus leadbeateri), Victoria.
Leadbeater’s possums weigh less than an apple and they’re fast! Researchers in the 1970s called them “fairy possums” – this animal wouldn’t be out of place in Tolkien’s Middle-Earth.
Honey possum, noolbenger (Tarsipes rostratus), southwest Western Australia.
The hummingbird of the mammal world, this tiny wonder weighs in at 15g and feeds entirely on nectar, utilising an extremely fast and highly evolved tongue to gather its daily needs. Male honey possums are smaller than females, but their testes are around 5% of their body weight – around 4kg for and adult human male and thelongest spermatozoa of any mammal in the world: 0.36mm (for comparison, an elephant’s sperm is just 0.056mm).
Mahogany glider (Petaurus gracilis), north Queensland Wet Tropics.
Soaring through open forests and woodlands, this stylishly striped species can travel up to 60m in one glide. The species was first recorded in the 1880s, but disappeared for almost a century until its rediscovery and naming in 1989. Its limited distribution in fragmented habitat means that it’s highly endangered.
Scaly-tailed possum (Wyulda squamicaudata), north-western Australia.
Not the most charismatic of names, but this shy species’ tail is actually quite fascinating, with small scales like “tiny fingernails” that allow the Wyulda to grasp rocks and trees for extra balance.
Narrow-toed feathertail glider (Acrobates pygmaeus), east coast Australia from Far North Queensland to western Victoria.
Star of the now defunct 1c coin, this “tiny acrobat” tends to be hard to spot, due to their size – around 8cm long – and the fact they spend most of their time more than 15m above the ground in canopies. As the name suggests, this species has a distinctive tail fringed with long stiff hairs, which acts as a rudder.
Mountain pygmy possum (Burramys parvus), alpine areas of NSW and Victoria.
Should you meet a critically endangered mountain pygmy-possum you might at first mistake it for a house mouse – they’re about the same size. But the pygmy-possum is a little larger and its tail – coiled and partly furry – and toes (five, not four front toes, and joined second and third back toes) give it away. The mountain pygmy-possum occupies in a limited range in elevations above 1300m in the high country of Victoria and NSW; it’s the only Australian mammal restricted to such alpine habitat. Mostly it survives on invertebrates such as caterpillars, beetles and especially bogong moths, and supplements its diet with fruits and seeds from the mountain plum pine and other heath species. It’s feared that the climate-related recent severe decline of bogong moth numbers may further threaten the mountain pygmy-possum’s survival. Fewer than 2000 individuals are estimated in the wild.
Green ringtail possum (Pseudochirops archeri), eastern Australia and Tasmania.
This plump tree-dweller – found in tropical rainforests from just north of Townsville to the Daintree – has fur follicles with black, yellow and white bands that give it a lime-green colour. Its unusual adaptations include a predilection for sleeping in the open in tree forks, and an ability to feed unaffected on the leaves of the stinging tree – a member of the nettle family renowned for the excruciating and long-lasting pain its plant hairs inflict on humans.
Sugar glider (Petaurus breviceps), northern and eastern Australia; slave-traded internationally.
Cutest possum in the possumiverse? The sugar glider would give this title a fair shake – one of the reason that its a favourite in the international exotic pet trade. With a total length – tail included – of only 25–30cm, thick, soft fur and large bulgy eyes it’s easy to see why people love sugar gliders. They’re opportunistic eaters, and can flip between carnivorous, insectivorous and plant-related diets. Fun fact: the sugar glider’s eyes are set wide apart to assist its airborne navigation – they allow for more precise triangulation of flight paths and landing spots.
Polling to determine the finalists of Australian Mammal of the Year is now closed. The Top Ten finalists will be announced on Monday 15 August and final voting for the Mammal of the Year will begin!