Leadbeater’s possum: a real-life forest fairy

Name: Leadbeater’s possum (Gymnobelideus leadbeateri), also known as the Bass River possum and the fairy possum

Size: Head-body length 16cm, tail length 17cm; weight 130g

Diet: Sap, gum, honeydew, invertebrates

Habitat: Restricted to wet forests 2–3 hours north-east of Melbourne

Conservation status: Critically endangered

Superpower: Cold tolerance – this small possum can withstand freezing temperatures in subalpine woodland and remains active throughout winter without going into torpor.

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It is rare to get a second chance to save a species from extinction, but that’s what occurred when Leadbeater’s possum was rediscovered in 1961 after half a century without a confirmed sighted. Credit: Tim Bawden

As light fades at the edge of a dark, moss-green gully lined with gnarled myrtle beeches, four small shadows emerge quickly and noiselessly into the night …

The story of Leadbeater’s possum is a story about trees – and a story about fire. The elusiveness of this animal hangs like mist, obscuring our view. We don’t know precisely where the first specimens were collected. Strange tales surround the discovery of others. This is an animal that knows how to hide. Cryptic. Elusive. Enigmatic. Until recently, the most basic questions have evaded us – how many are there? Where are they?

Endemic to Victoria, Leadbeater’s possums weigh less than an apple – and they’re fast! Their club-shaped tail conveys emotion; their spatulate toes are reminiscent of a gecko’s. Researchers in the 1970s called them “fairy possums” – this animal wouldn’t be out of place in Tolkien’s Middle-Earth.

In 1960, Leadbeater’s possum was described as “certainly, or almost certainly, extinct”. One year later, after 50 years without a confirmed sighting, it was rediscovered in forest north-east of Melbourne. A victim of past climate change, its entire distribution is now confined to a tiny area of forest – just 70 by 95 kilometres.

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Montane ash forest supports the majority of population – however, Leadbeater’s possums also inhabit snow gum woodlands at 1400-metre elevation, and a single patch of lowland swamp forest at Yellingbo. This last group of possums are genetically distinct and the last remnant of a once-wider lowland occurrence.

Each of these forest types has a different character, as do the possums that live there. Yellingbo is intimate, the possums low down, and the challenge is water. In montane ash forest, the challenge is height; in snow gum, freezing temperatures. Adapted to cold, this animal runs into the white of winter.

Leadbeater’s possums live in family groups comprising a single breeding pair with their young. By day, they sleep huddled together, sharing warmth in dense doonas of shredded bark within tree hollows. Strong neighbourhoods are made up of many families, each with fidelity to their home patch of forest. Family histories are connected to patches of land.

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The history of Leadbeater’s possum tells us to take nothing for granted. The Black Saturday fires in 2009 were a devastating illustration of how quickly circumstances can change. Credit: Tim Bawden

It takes a mountain ash almost 200 years to develop hollows suitable for a family of Leadbeater’s possums (they’re fussy – small entrance, large living room). Home is everything to this animal – both their patch of forest and their tree houses.

Fires, logging, decay and collapse have combined to make old trees with hollows scarce. The quality of forest matters. Leadbeater’s possums seek the “Goldilocks zone” – young trees to feed in, old trees to sleep in.

This possum challenges how we think about time. Suitable hollows take two centuries to develop, while fire can destroy them overnight. Eighty percent of the possum’s range burnt in 1939, a third in 2009.

Few encounter Leadbeater’s possums in the wild. They live in places that are uncomfortable for us. The possum’s elusiveness has not served it well. It’s hard to love what you cannot see.

But we can love an image, an impression. A dream.

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