Mountain Pygmy Possums Bounce Back from Brink of Extinction

Parks Victoria

An adorable Mountain Pygmy Possum stares directly into your soul and it sits on a persons arm

A hardboiled egg weighs more than a Mountain Pygmy Possum after its hibernation. Image credit: Parks Victoria.

The Mountain Pygmy Possum (Burramys parvus) has an incredible story to tell. The animal weighs as much as a hardboiled egg (at 45 grams) and demonstrates several quirks that no other native marsupial does on the continent. It was initially discovered as a few fragmentary fossils in 1894, but on a frosty morning in August of 1966, the unthinkable happened; a chance discovery brought the fossils back to life. Now, the race is on to bring this critically endangered species back from the brink of extinction, as Parks Victoria and other agencies battle against climate change to protect this "bug-eyed" possum.

Rediscovery

Finding a "thought-to-be-extinct" animal is rare, especially in Australia where the extinction rate is higher than on any other continent. Worldwide, this occurs from time to time: the most famous example of rediscovery was of the Coelacanth, a lobe finned fish that can reach more than two metres in length. Prior to 1938, the last evidence of this bizarre fish was cemented in late Cretaceous sediments, and just like the dinosaurs, were thought to be victims of the mass extinction event over 66 million years ago. But in December of 1938, a Coelacanth was captured by local trawlermen off the coast of South Africa and caused a stir in the scientific community.

In the Victorian alpine/subalpine areas, rediscoveries of extinct flora aren't uncommon. The critically endangered Mountain Burr-daisy (Calotis pubescens) was thought to be extinct in Victoria but was rediscovered in 2009 from a single location that is now protected by Parks Victoria. The Kiandra Leek Orchid (Prasophyllum retroflexum) is now known from two distinct populations in the subalpine regions in Victoria (and two from NSW), after being thought extinct for more than 80 years.

A purple and yellow flower is standing amongst the grass. A small babbling stream with grasses and sedges on either side, is protected by a fence.

The threatened Mountain Burr-daisy occurs at only one location, where it is protected by a fenced enclosure, preventing it from being grazed and trampled by feral horses, deer, and pigs. Image credit: Parks Victoria.

But finding an extinct animal known only from the fossil record, alive and breathing, is something else.

The Mountain Pygmy Possum was first known to western science as a single jawbone cemented in a small limestone block and a few isolated teeth by Robert Bloom in 1894. The remains were estimated to be over 15,000 years of age and found in cave deposits in NSW on Gundungurra Country.

A picture of the jaw is illustrated, showing the jaw in two segments and an elongated premolar tooth.

The identity of this jawbone confused palaeontologists for almost 50 years, until better techniques for isolating bone from the rocks were utilised. At one stage, it was thought to be a missing link between possums and kangaroos/wallabies. Image credit: Robert Broom.

For over 70 years, the only known evidence of the Mountain Pygmy Possum was of a handful of fossil bones and teeth, until one day in August of 1966. A group of skiers on Mt Hotham discovered a "strange looking rat" in their ski-hut, that was clearly different from the other rodents. Reports vary, but some state that this strange-looking animal was "stealing the bacon from their stove". The strange rat was captured, and affectionately named George. He was taken to Melbourne by one of the skiers who intended to give it to his 4-year-old daughter as a pet but was later confiscated to be studied for science.

Australian palaeontologist and botanist Norman Wakefield made the "EUREKA" moment whilst studying George. It was an incredible moment in Australian science, but it would take a few years until scientists found another living Mountain Pygmy Possum and could start to understand the population dynamics of this enigmatic possum species.

A newspaper clipping of a Mountain Pygmy Possum is shown, with text underneath:

This is one of the few images of George that still exist, announcing the existence of a living Mountain Pygmy Possum in a 1967 newspaper clipping. Image provided by Peter Homan.

Habitat

It was immediately obvious that the Mountain Pygmy Possum was in dire straits. Its population was restricted to alpine areas above 1300 metres (thanks in part to the mass inland aridification of Australia from the last ice age), and in Victoria, these tiny critters are currently found in two succinct areas: Mt Bogong to Mt Higginbotham and Mt Buller, all located within culturally important areas of Aboriginal land (Kosciusko National Park in NSW also has another geographically isolated population). It is the only Australian mammal restricted to alpine/subalpine environments. The most prominent populations are in Victoria, with more than three quarters of the 2000 or so known individuals being recorded in the state.

You'd be forgiven for thinking that this possum resides in the trees like its arboreal cousins the Pygmy Possums (Cercartetus sp.), but this possum lives on the ground, amongst the boulder fields which are dominated by the Mountain Plum Pine. Their populations are connected to known expanses of Bogong moth habitat, as the moth is the most important part of their overall diet.

Spindly Mountain Plum pine wraps itself around a boulder-field, with a person surveying the area in the background.

When George was found, it was initially thought he was a hitchhiker from lower altitudes. Mountain Pygmy Possums are the only possum species in Australia that don't live in trees. Image credit: Parks Victoria.

Behaviour and Diet

With an average weight of 45 grams after their seven-month hibernation, this species is the definition of a survivalist. Their hibernation is something no other marsupial does; they drop their body temperature from around from 35 degrees Celsius in the warmer months to just above freezing, to a staggering 2 degrees Celsius, as they nest under the snow. Much like a squirrel, they store seeds during the warmer months and occasionally munch on them during the harsh and oppressive colder periods.

They'll chomp on all sorts of things, from the berries of numerous shrubs, a range of seeds and various small bugs and lick the nectar from flowers, but by far the most important contributor to their diet are Bogong moths (Agrotis infusa).

A Bogong moth is lying on top of the green grass.

Each female Bogong moth can lay in upwards of 2000 eggs every season. Image credit: Museums Victoria.

These moths weigh less than a tic tac and annually migrate across southern Australia in their billions. In the Victorian alps, they remain in their dormant state for months, where they are feasted upon by opportunistic possums. But as recently as 2017, the moth was placed on the IUCN's "Red List of Threatened Species", after surveys discovered up to 99% of their population had disappeared, due in part to major land clearing for crops along the Murray Darling basin and changing farming practices. This population is thought to be slowly recovering, (thanks to wetter weather in the last few years), but immediate intervention was required. Parks Victoria partnered with Zoos Victoria to distribute "bogong bikkies", a delicious nutty biscuit created for the possum, in lieu of this population crash and in one of their last remaining strongholds in the Alpine National Park. It continues to be hugely successful.

Threats to Survival and Conservation in Parks Victoria

As mentioned previously, the density of Bogong moth populations is a huge factor in successful breeding efforts for this possum. In 2017-18, more than half of all females monitored lost their litters. There are numerous overarching threats, and Parks Victoria has a tremendous legislative responsibility to look after the habitat of this possum.

A cute little Mountain Pygmy possum is eating the fruit of a Mountain plum pine on a rock outcrop, grasping the berry in its hands and bringing it to its mouth.

One must become ChOnK if they are to survive the harsh winter, as this individual munches on the berry of a Mountain Plum Pine. Image credit: Parks Victoria

Back in 1983, the Alpine National Park was extended to include important Mountain Pygmy Possum habitat on the western slopes of Mt Higginbotham. Throughout this time, Parks Victoria and numerous other agencies have successfully managed the critical interface between their habitat and the numerous hazards that threaten their survival. To carry this out effectively, Parks Victoria must:

1) Actively monitor and reduce known populations of foxes and feral cats in this area through various control methods. The monitoring of rabbit populations is key, as they can sustain high populations of pest predators. The scat and gut contents from feral cats and foxes are routinely analysed to determine if this possum is on the menu.

A Parks Victoria staff member is setting up a trap for a feral cat.

Parks Victoria staff have previously used cat traps to control populations of feral cats. Feral cats are hardwired to be attracted to smelly and at times, gut wrenching scents of dead animals, but have proven difficult to catch in national parks. Image credit: Parks Victoria

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Rediscovery

Habitat

Behaviour and Diet

Threats to Survival and Conservation in Parks Victoria

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