Leadbeater's possum (Gymnobelideus leadbeateri) is a critically endangered possum largely restricted to small pockets of alpine ash, mountain ash, and snow gum forests in the Central Highlands of Victoria, Australia, north-east of Melbourne. In June 2025 it was reported that an image of a sole possum was recorded on a camera trap in October 2024 near Yarrangobilly Caves, Southern NSW, within the Kosciuszko National Park. It is primitive, relict, and non-gliding, and, as the only species in the petaurid genus Gymnobelideus, represents an ancestral form. Formerly, Leadbeater's possums were moderately common within the very small areas they inhabited; their requirement for year-round food supplies and tree-holes to take refuge in during the day restricts them to mixed-age wet sclerophyll forest with a dense mid-story of Acacia. The species was named in 1867 after John Leadbeater, the then taxidermist at the Museum Victoria. They also go by the common name of fairy possum. On 2 March 1971, the State of Victoria made the Leadbeater's possum its faunal emblem.
History Leadbeater's possum is thought to have evolved about 20 million years ago. It was not discovered until 1867 and was originally known only through five specimens, the last one collected in 1909. From that time on, the fear that it might be extinct gradually grew into near-certainty after the swamps and wetlands in Australia around Bass River in south-west Gippsland were drained for farming in the early 1900s. By the time of the 1939 Black Friday fires, the species was thought to have been extinct. Then, on 3 April 1961, a member of the species was rediscovered by naturalist Eric Wilkinson in the forests near Cambarville, and the first specimen in more than 50 years was captured later in the month. In 1961, a colony was discovered near Marysville. Extensive searches since then have found the existing population in the highlands. However, the availability of suitable habitat is critical: forest must be neither too old nor too young, with conservation efforts for Leadbeater's possum involving protection of remaining old-growth stands, and maintenance of younger stands that are allowed to attain hollow-bearing age. The combination of 40-year-old regrowth (for food) and large dead trees left still standing after the fires (for shelter and nesting) allowed the Leadbeater's possum population to expand to an estimated peak of about 7500 in the early 1980s. From its peak in the 1980s, the Leadbeater's possum population was expected to further decline rapidly, by as much as 90%, due to a habitat bottleneck. The population has dropped sharply since 1996. Particularly, the February 2009 Black Saturday bushfires destroyed 43% of Leadbeater's possums' habitat in the Central Highlands, halving the wild population to 1,500. A study in 2014 concluded there is a 92% chance the Leadbeater's ecosystem in the Victoria central highlands will collapse within 50 years.
Habits Leadbeater's possums are rarely seen as they are nocturnal, fast-moving, and occupy the upper storey of some of the tallest forest trees in the world. They have an average body length of 33 cm (13 inches) with the tail included. They live in small family colonies of up to 12 individuals, including one monogamous breeding pair. Mating occurs only once a year, with a maximum of two joeys being born to each pair. All members sleep together in a nest made out of shredded bark in a tree hollow, anywhere from 6 to 30 metres above ground level and roughly in the centre of a territory of 3 hectares, which they defend actively. The society of Leadbeater's possums is matriarchal: each group is dominated by only one female Leadbeater's possum that is active in expelling outsiders. Other juvenile females are weaned off before they reach sexual maturity. In addition, female Leadbeater's possums are more aggressive in nature, often engaging in frequent fights with other females, including their own daughters. Due to the constant attacks, young females are forced to leave much earlier than their male brothers, which results in the extremely high male to female ratio of 3:1. Solitary Leadbeater's possums have difficulty surviving: when young males disperse at about 15 months of age, they tend either to join another colony as a supernumerary member, or to gather together into bachelor groups while they wait to find a mate. At dusk, Leadbeater's possums emerge from the nest and spread out to forage in the sub-canopy, often making substantial leaps from tree to tree (they require continuous understory to travel). Their diet is omnivorous: feeding on a range of wattle saps and exudates, lerps, and a high proportion of arthropods which they find under the loose bark of eucalypts, including spiders, crickets, termites and beetles. Plant exudates make up 80% of their energy intake, but the protein provided by the arthropods is essential for successful breeding. Births are usually timed for the beginning of winter (May and June) or late spring (October and November). Most litters are of one or two young, which stay in the pouch for 80 to 90 days, and first emerge from the nest following this. Young, newly independent Leadbeater's possums are very vulnerable to owls. As of 2013, Leadbeater's possums are found in three habitat types: lowland swamp gum, of Yellingbo Nature Conservation Reserve; montane ash forest, wet sclerophyll forest dominated by mountain ash, shining gum and alpine ash with a dense mid-story of acacia species; sub-alpine woodlands of Mount Baw Baw, Lake Mountain and Mount Bullfight.
Threats
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