Leadbeater's Possum
Encyclopedia
Leadbeater's Possum is an endangered possum
restricted to small pockets of remaining old growth mountain ash
forests in the central highlands of Victoria (Australia) north-east of Melbourne. Leadbeater's Possums can be moderately common within the very small areas they inhabit: 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
. It is the only species in the Gymnobelideus genus. It was named after John Leadbeater the then taxidermist at the Museum of Victoria.
In 1968, the State of Victoria
made Leadbeater's Possum its faunal emblem.
in south-west Gippsland
were drained for farming in the early 1900s. Then, on 3 April 1961, a member of the species was rediscovered by naturalist Eric Wilkinson, and the first specimen in more than 50 years was captured later in the month.
In 1965, 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.
A formerly fairly healthy population was ascribed to the terrible Black Friday
fires that swept through Australia in 1939: 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 (since declining to 2000). However, the old trees were gradually decaying and the regrowth maturing. Prior to European settlement, a similar situation would have forced migration to other areas — something which is not a realistic option now because of extensive land clearing over the last hundred years or so.
From its peak in the 1980s, the Leadbeater's Possum population is expected to further decline rapidly, by as much as 90%. The population has dropped sharply since 1996. Failing human intervention, and assuming that a reduced population could have survived that long, natural tree hollow
s were expected to develop in the Black Friday regrowth as the trees reached about 150 years of age in the second half of the 21st century, and numbers to begin climbing again.
However, the status of Leadbeater's Possum is in even more doubt following the disastrous bushfires that swept its only known habitat on Black Saturday in February 2009. Large areas of bushland around Marysville
, Narbethong and Healesville have been destroyed.
Solitary Leadbeater's Possums have difficulty surviving: when young males disperse at about 15 months of age, they tend to either join another colony as a supernumerary member, or gather together into bachelor groups while they await an opportunity to find a mate.
At dusk, Leadbeater's Possums emerge from the nest and spread out to forage in the canopy, often making spectacular leaps from tree to tree (they require continuous understory to travel). Their diet is omnivorous: they take a range of saps and exudates, lerp
s, and a high proportion of arthropod
s which they find under the loose bark of eucalypts: spiders, crickets, beetles, and the like. 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 or 90 days, and first emerge from the nest about three weeks after that. Young, newly independent Leadbeater's Possums are very vulnerable to owl
s.
, logging
continues to pose a critical threat to Leadbeater's possum. The logging in 1993 of "much of the possum's habitat, as zone one" a five hectare reserve east of Powelltown
, followed a "mapping error." Author, Peter Preuss, stated that the possum's population faltered in 1997 with current habitat (limited to a 50-square-kilometre area) under threat from logging. He emphasised the need to relaunch a breeding program.
Dr. David Lindenmeyer (Australian National University
) has argued that the need for nest boxes indicates that logging practices are not ecologically sustainable for conserving hollow-dependent species like Leadbeater's possum. Studies have shown that clear-felling
operations, such as the logging run in state forest
between the Yarra Ranges National Park and Mount Bullfight Conservation Reserve in February 2006, lead to the deaths of most possums in the area - "Adult animals have a strong affinity with their home range and are reluctant to move".
Despite a joint Federal and State government plan to save it, since the 1980s, the Leadbeater's possum population has halved to around 2000. Many more were killed early in 2007 when VicForests bulldozed large firebreaks through Leadbeater's monitoring stations following the Christmas fires - firebreaks and clear-felling also prevent breeding with nearby colonies.
With its known habitat destroyed in the disastrous bushfires of February 2009 - large areas of forest around Marysville
, Narbethong and Healesville - the species status is currently in doubt. The mapped distribution of the Leadbeater's possum was within the area burnt by the fires.
With few individuals having survived the fires, salvage logging
since the fires has posed a further risk to this extremely diminished population , with clear-felling
also approved by VicForests in the few remaining unburnt areas, such as the Kalatha Creek area of Toolangi
in 2010 , a move opposed by the Yarra Ranges Shire Council.
Following the death of Kasia, the last captive Leadbeater's Possum, at Toronto Zoo
in January 2010, there are now no Leadbeater's Possums in captivity anywhere in the world and so no breeding program
to assist this animal's survival. The last Australian specimen held at Healesville Sanctuary
died in May 2006. The formation of the Friends of Leadbeater's Possum group is seen as a positive step towards raising the profile of this animal and an opportunity to continue to lobby the State Government to properly protect its declining habitat.
Possum
A possum is any of about 70 small to medium-sized arboreal marsupial species native to Australia, New Guinea, and Sulawesi .Possums are quadrupedal diprotodont marsupials with long tails...
restricted to small pockets of remaining old growth mountain ash
Eucalyptus regnans
Eucalyptus regnans, known variously by the common names Mountain Ash, Victorian Ash, Swamp Gum, Tasmanian Oak or Stringy Gum, is a species of Eucalyptus native to southeastern Australia, in Tasmania and Victoria...
forests in the central highlands of Victoria (Australia) north-east of Melbourne. Leadbeater's Possums can be moderately common within the very small areas they inhabit: their requirement for year-round food supplies and tree-holes to take refuge in during the day restricts them to mixed-age wet sclerophyll
Sclerophyll
Sclerophyll is the term for a type of vegetation that has hard leaves and short internodes . The word comes from the Greek sclero and phyllon ....
forest with a dense mid-story of Acacia
Acacia
Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...
. It is the only species in the Gymnobelideus genus. It was named after John Leadbeater the then taxidermist at the Museum of Victoria.
In 1968, the State of Victoria
Victoria (Australia)
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
made Leadbeater's Possum its faunal emblem.
History
The possum 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 RiverBass River (Victoria)
The Bass River is a relatively short coastal river located in the Bass Coast Shire of Gippsland, Victoria, Australia. The river headwaters are in the Strzelecki Ranges, north of the town of Korumburra, flowing west, then west-southwest before entering Western Port, near the town of Bass.It was...
in south-west Gippsland
Gippsland
Gippsland is a large rural region in Victoria, Australia. It begins immediately east of the suburbs of Melbourne and stretches to the New South Wales border, lying between the Great Dividing Range to the north and Bass Strait to the south...
were drained for farming in the early 1900s. Then, on 3 April 1961, a member of the species was rediscovered by naturalist Eric Wilkinson, and the first specimen in more than 50 years was captured later in the month.
In 1965, a colony was discovered near Marysville
Marysville, Victoria
Marysville is a small town, 34 kilometres north-east of Healesville, in the Shire of Murrindindi in Victoria, Australia. The town, which previously had a population of around 500 people, was devastated by the Murrindindi Mill bushfire on 7 February 2009. On 19 February 2009 the official death toll...
. 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.
A formerly fairly healthy population was ascribed to the terrible Black Friday
Black Friday (1939)
The Black Friday fires of 13 January 1939, in Victoria, Australia, were considered one of the worst natural bushfires in the world, and certainly the single worst in Australian history as a measure of land affected...
fires that swept through Australia in 1939: 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 (since declining to 2000). However, the old trees were gradually decaying and the regrowth maturing. Prior to European settlement, a similar situation would have forced migration to other areas — something which is not a realistic option now because of extensive land clearing over the last hundred years or so.
From its peak in the 1980s, the Leadbeater's Possum population is expected to further decline rapidly, by as much as 90%. The population has dropped sharply since 1996. Failing human intervention, and assuming that a reduced population could have survived that long, natural tree hollow
Tree hollow
A tree hollow or tree hole is a semi-enclosed cavity which has naturally formed in the trunk or branch of a tree. These are predominantly found in old trees, whether living or not...
s were expected to develop in the Black Friday regrowth as the trees reached about 150 years of age in the second half of the 21st century, and numbers to begin climbing again.
However, the status of Leadbeater's Possum is in even more doubt following the disastrous bushfires that swept its only known habitat on Black Saturday in February 2009. Large areas of bushland around Marysville
Marysville, Victoria
Marysville is a small town, 34 kilometres north-east of Healesville, in the Shire of Murrindindi in Victoria, Australia. The town, which previously had a population of around 500 people, was devastated by the Murrindindi Mill bushfire on 7 February 2009. On 19 February 2009 the official death toll...
, Narbethong and Healesville have been destroyed.
Habits
Leadbeater's Possums are rarely seen: they are nocturnal, small (about 10 cm long and about 90 grams, or the size of a small rat), fast-moving, and occupy the upper story of some of the tallest forests in the world. They live in small family colonies of up to 24 individuals, usually a breeding pair, their offspring, and sometimes an unrelated extra male or two. 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 10,000 to 20,000 square metres, which they defend actively. The senior female is the main defender: she is more active in expelling outsiders, and attacks her daughters when they reach sexual maturity at about 14 months of age, forcing them to disperse earlier than male children. In consequence, mortality among young female Leadbeater's Possums is high—average female lifespan is little more than 27 months, as opposed to about 10 years in captivity.Solitary Leadbeater's Possums have difficulty surviving: when young males disperse at about 15 months of age, they tend to either join another colony as a supernumerary member, or gather together into bachelor groups while they await an opportunity to find a mate.
At dusk, Leadbeater's Possums emerge from the nest and spread out to forage in the canopy, often making spectacular leaps from tree to tree (they require continuous understory to travel). Their diet is omnivorous: they take a range of saps and exudates, lerp
Lerp (biology)
In biology, a lerp is a structure of crystallized honeydew produced by larvae of psyllid insects as a protective cover.-Host plants:Some of the host plants on which lerp is often found include:* Eucalyptus dumosa...
s, and a high proportion of arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s which they find under the loose bark of eucalypts: spiders, crickets, beetles, and the like. 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 or 90 days, and first emerge from the nest about three weeks after that. Young, newly independent Leadbeater's Possums are very vulnerable to owl
Owl
Owls are a group of birds that belong to the order Strigiformes, constituting 200 bird of prey species. Most are solitary and nocturnal, with some exceptions . Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish...
s.
Status
Endangered and with a range limited only to the Upper Yarra ValleyYarra Valley
The Yarra Valley is the name given to the region surrounding the Yarra River in Victoria, Australia. The river originates approximately 90 kilometres east of the City of Melbourne and flows towards it and out into Port Phillip Bay...
, logging
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...
continues to pose a critical threat to Leadbeater's possum. The logging in 1993 of "much of the possum's habitat, as zone one" a five hectare reserve east of Powelltown
Powelltown, Victoria
Powelltown is a town in Victoria, Australia, 70 km east from Melbourne's central business district. Its Local Government Area is the Shire of Yarra Ranges. At the 2006 Census, Powelltown had a population of 201....
, followed a "mapping error." Author, Peter Preuss, stated that the possum's population faltered in 1997 with current habitat (limited to a 50-square-kilometre area) under threat from logging. He emphasised the need to relaunch a breeding program.
Dr. David Lindenmeyer (Australian National University
Australian National University
The Australian National University is a teaching and research university located in the Australian capital, Canberra.As of 2009, the ANU employs 3,945 administrative staff who teach approximately 10,000 undergraduates, and 7,500 postgraduate students...
) has argued that the need for nest boxes indicates that logging practices are not ecologically sustainable for conserving hollow-dependent species like Leadbeater's possum. Studies have shown that clear-felling
Clearcutting
Clearcutting, or clearfelling, is a controversial forestry/logging practice in which most or all trees in an area are uniformly cut down. Clearcutting, along with shelterwood and seed tree harvests, is used by foresters to create certain types of forest ecosystems and to promote select species that...
operations, such as the logging run in state forest
State forest
A state forest is a forest that is administered or protected by some agency of a sovereign state.The precise application of the term varies by jurisdiction...
between the Yarra Ranges National Park and Mount Bullfight Conservation Reserve in February 2006, lead to the deaths of most possums in the area - "Adult animals have a strong affinity with their home range and are reluctant to move".
Despite a joint Federal and State government plan to save it, since the 1980s, the Leadbeater's possum population has halved to around 2000. Many more were killed early in 2007 when VicForests bulldozed large firebreaks through Leadbeater's monitoring stations following the Christmas fires - firebreaks and clear-felling also prevent breeding with nearby colonies.
With its known habitat destroyed in the disastrous bushfires of February 2009 - large areas of forest around Marysville
Marysville, Victoria
Marysville is a small town, 34 kilometres north-east of Healesville, in the Shire of Murrindindi in Victoria, Australia. The town, which previously had a population of around 500 people, was devastated by the Murrindindi Mill bushfire on 7 February 2009. On 19 February 2009 the official death toll...
, Narbethong and Healesville - the species status is currently in doubt. The mapped distribution of the Leadbeater's possum was within the area burnt by the fires.
With few individuals having survived the fires, salvage logging
Salvage logging
Salvage logging is the practice of logging trees in forest areas that have been damaged by wildfire, flood, severe wind, disease, insect infestation, or other natural disturbance.The primary motivation of salvage logging is economic...
since the fires has posed a further risk to this extremely diminished population , with clear-felling
Clearcutting
Clearcutting, or clearfelling, is a controversial forestry/logging practice in which most or all trees in an area are uniformly cut down. Clearcutting, along with shelterwood and seed tree harvests, is used by foresters to create certain types of forest ecosystems and to promote select species that...
also approved by VicForests in the few remaining unburnt areas, such as the Kalatha Creek area of Toolangi
Toolangi
Toolangi is a rural township in Victoria, Australia. At the 2006 Census, Toolangi and the surrounding area had a population of 871.The township of Toolangi is situated on the edge of the Toolangi State Forest...
in 2010 , a move opposed by the Yarra Ranges Shire Council.
Following the death of Kasia, the last captive Leadbeater's Possum, at Toronto Zoo
Toronto Zoo
The Toronto Zoo is a zoo located in Toronto, Ontario, Canada. It opened August 15, 1974 as the Metropolitan Toronto Zoo and is owned by the City of Toronto; the word "Metropolitan" was dropped from its name when the cities of the Municipality of Metropolitan Toronto were amalgamated to form the...
in January 2010, there are now no Leadbeater's Possums in captivity anywhere in the world and so no breeding program
Breeding program
Breeding programs help animals to breed and can be good for animals as well as the agricultural economy.A breeding program is the planned breeding of a group of animals or plants, usually involving at least several individuals and extending over several generations...
to assist this animal's survival. The last Australian specimen held at Healesville Sanctuary
Healesville Sanctuary
Healesville Sanctuary, or the Sir Colin MacKenzie Fauna Park, is a zoo specializing in native Australian animals. It is located at Healesville in rural Victoria, Australia, and has a history of breeding native animals. It is one of only two places to have successfully bred a platypus, the other...
died in May 2006. The formation of the Friends of Leadbeater's Possum group is seen as a positive step towards raising the profile of this animal and an opportunity to continue to lobby the State Government to properly protect its declining habitat.
See also
- Close relatives of Leadbeater's Possum: Sugar GliderSugar GliderThe sugar glider is a small gliding possum originating from the marsupial family.The sugar glider is native to eastern and northern mainland Australia and is also native to New Guinea and the Bismarck Archipelago.- Habitat :Sugar gliders can be found all throughout the northern and eastern parts of...
, Squirrel GliderSquirrel GliderThe Squirrel Glider is a nocturnal gliding possum, one of the wrist-winged gliders of the genus Petaurus.-Habitat:...
, Yellow-bellied GliderYellow-bellied GliderThe Yellow-bellied Glider is an arboreal and nocturnal gliding possum that lives in a narrow range of native eucalypt forests down eastern Australia, reaching from northern Queensland to Victoria.-Habitat:...
, Mahogany GliderMahogany GliderThe mahogany glider is an endangered gliding possum native to a small region of coastal Queensland.-Appearance:A nocturnal arboreal marsupial, the mahogany glider closely resembles the sugar glider, the squirrel glider and the yellow-bellied glider., but is noticeably larger than any of its...
, Striped PossumStriped PossumThe Striped Possum is a member of the Petauridae family, one of the marsupial families. The species is black with three white stripes running head to tail, and its head has white stripes that form a 'Y' shape... - Favoured habitat trees: Mountain AshEucalyptus regnansEucalyptus regnans, known variously by the common names Mountain Ash, Victorian Ash, Swamp Gum, Tasmanian Oak or Stringy Gum, is a species of Eucalyptus native to southeastern Australia, in Tasmania and Victoria...
, Alpine Ash, Shining Gum