History of Leadbeater's Possum
McCoy’s 1885 Prodromus, included this coloured version of a drawing of Gymnobelideus leadbeateri that had been used in the 1867 scientific description.
The evolution of the ‘naked dart’
Leadbeater’s possum evolved up to 20 million years ago.
It was first scientifically described by Frederick McCoy in 1867 on the basis of two specimens sent to the recently established Melbourne Museum. The specimens had been collected by Jim Peters from scrub on the banks of the Bass River in West Gippsland. McCoy noted the superficial similarity of the specimens to the previously described Sugar Glider, known at the time as Belideus*, Greek for “dart”, because of its gliding ability. The obvious difference was that the new possum lacked a gliding membrane, so McCoy called it the “naked dart” or Gymnobelideus. The specific name, leadbeateri, comes from the taxidermist at the museum, John Leadbeater, who preserved the first two skins, which are still in the museum’s collection.
Over the following decades the swamp forests of the Bass River area were drained and cleared to make way for agriculture. By the early 1900s only a handful of specimens had been collected, the forests were gone and it was soon presumed the species was extinct.
By 1960 the animal had not been seen alive for 50 years and it was declared, “almost certainly extinct”. But on 3 April 1961, the species was rediscovered by naturalist Eric Wilkinson in the forests at Cambarville and Tommy’s Bend, near Marysville, The first specimen collected in more than 50 years was obtained later in the month. Extensive searches followed and it was established that the existing population is limited to Victoria’s Central Highlands. However, the availability of suitable habitat is critical: Leadbeater’s possum requires three essential components, big, old hollow-bearing trees in which it can build its nest, a mid-storey of wattles in which it feeds on sap and a dense under-storey providing horizontal connectivity so that it can move safely around. Conservation efforts for Leadbeater’s possum involve protection of remaining old-growth trees, and maintenance of mature stands that will, in time, develop hollows and provide future habitat.
The combination of 40-year-old wattle regrowth (for food) and large dead and decaying Eucalyptus trees left still standing after the 1939 fires (for shelter and nesting) allowed the Leadbeater’s possum population to expand to an estimated peak of about 5000 in the early 1980s. From that peak the Leadbeater’s possum population was expected to further decline rapidly, by as much as 90%, due to a habitat bottleneck as suitable den trees decayed and eventually collapsed. The use of the industrial clear fall system of logging contributed to the destruction of existing hollow-bearing trees and the absence of creation of new ones. The February 2009 Black Saturday bushfires destroyed around 45% of Leadbeater’s Possum’s reserved habitat in the Central Highlands, possibly halving the wild population. An Ecosystem Assessment published in 2014 (Burns et al.) concluded the Mountain Ash ecosystem in the Victorian Central Highlands is Critically Endangered, with a high probability it will collapse within 50 years.
The Sugar Glider is now known as Petaurus breviceps.
Highs and Lows
Leadbeater’s possums also live in Snow Gum woodland on Mt Bullfight, about 9 kms from Lake Mountain. This area was also affected by the 2009 fires but not burned as severely as Lake Mountain.
In 1986 a new population of Leadbeater’s possums was unexpectedly found at the Yellingbo Nature Conservation Reserve at Yellingbo in the Upper Yarra Valley. It was later found that these lowlands animals are genetically distinct from those in the montane Ash forests, having been separated for up to 10,000 years. The lowlands Leadbeater’s possums at Yellingbo may be the last remaining representatives of the original West Gippsland swamp forest population described by McCoy in 1867. At the current time (June 2022) less than 40 of these special animals survive.
Lost and Found
A presentation video celebrating the rediscovery of the Leadbeater’s possum.
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