Animal Info - Leadbeater's Possum
Gymnobelideus leadbeateri
Contents
1. Profile (Picture)
2. Tidbits
3. Status and Trends (IUCN Status, Countries Where
Currently Found, Population Estimates, History of Distribution, Threats and Reasons
for Decline)
4. Data on Biology and Ecology (Weight, Habitat, Age to Maturity, Birth
Season, Birth Rate, Early Development, Dispersal, Diet, Social
Organization, Age and Gender Distribution, Mortality and Survival, Density and Range, Minimum Viable Population)
5. References
Profile
Pictures: Leadbeater's
Possum #1 (16 Kb JPEG) (Unique
Austral. Anim.); Leadbeater's
Possum #2 (30 Kb JPEG) (Unique
Austral. Anim.); Leadbeater's
Possum #3 (73 Kb JPEG) (Mus.
Vict.); Leadbeater's
Possum #4 (97 Kb JPEG) (Terrambiente)
Leadbeater's possum is a small marsupial weighing
120 - 160 g (4.3 - 5.8 oz). It is arboreal and nocturnal, and constructs a nest of loosely matted bark
in a hollow tree. Leadbeater's possum requires a forest containing large living or dead
mountain ash trees with hollows in which to nest and an understory
containing wattle acacia which supplies gum to supplement its main diet of insects. Its
society is based on a matriarchal system.
Individual females occupy large nests in hollow trees and actively defend a surrounding territory from other unrelated females. The family
group may contain several generations of offspring as well as unrelated males. Mating is monogamous and male partners assist females in defense
of territories against unrelated females.
Leadbeater's possum probably had a wide former range in the state of Victoria, Australia, but it was rare by the time it was discovered
by Western science in 1867. Until recently, it was regarded as extinct, after disastrous
fires throughout its range in 1939. However, in 1961 a small colony was rediscovered near
Marysville, Victoria. As of 1996 it was confined to an area of about 3500 sq km (1350 sq
mi) near the western limit of Victoria's Central Highlands.
Climate and flora changes since the Pleistocene
led to competition with the glider Petaurus breviceps and the glider appears to
have been more successful than Leadbeater's possum. The main concern for the species'
survival now are habitat fragmentation and the decline of suitable hollow-bearing trees
due to natural attrition, fire and the activities of timber harvesting.
Tidbits
*** Leadbeater's possum is the official animal of Victoria State, Australia.
*** By cutting notches in the bark of a tree with its teeth, it causes the tree to
exude gum, which it eats.
*** The mountain ash tree required by Leadbeater's possum is the world's tallest
hardwood (up to 100 m (330')) and is Australia's most valued timber producing tree.
*** The fact that it is the adult female, and not the male, that shows the most
aggression socially is uncharacteristic of mammals.
Status and Trends
- 1960's: Insufficiently Known
- 1970's - 1994: Endangered
- 1996 - 2004: Endangered (Criteria: A2c, E) (Population Trend:
Decreasing) (IUCN
2004)
Countries Where Leadbeater's Possum Is Currently Found:
2004: Occurs in Australia (Victoria). (IUCN
2004)
Population Estimates:
[Note: Figures given are for wild populations only.]
History of Distribution:
Leadbeater's possum probably had a wide former range in the state of Victoria, Australia, but it was rare by the time it was discovered
by Western science in 1867. Its previous range also included areas south and northeast of
its present distribution. In addition, fossils from New South Wales have been discovered.
Until recently, it was regarded as extinct, after disastrous fires throughout its range in
1939. However, in 1961 a small colony was rediscovered in the Cumberland Valley area near
Marysville, Victoria. By 1990 it had been found at more than 50 localities scattered over
1000 sq km (385 sq mi) of forest from Mt. Torbreck to Mt. Baw Baw in southeast Victoria.
As of 1996 it was confined to an area of about 3500 sq km (1350 sq mi) near the western
limit of Victoria's Central Highlands, including the upper reaches of the La Trobe,
Thomson, Bunyip, Yarra and Goulburn River systems at altitudes between 500 and 1500 m
(1600 - 4900'). There is also a small, isolated population near Yellingbo. (Maxwell et al. 1996)
Distribution
Map #1 (4 Kb GIF) (Maxwell et al. 1996)
Distribution Map #2 (7 Kb JPEG) (Unique
Austral. Anim.)
Threats and Reasons for Decline:
Climate and flora changes since the Pleistocene
led to competition with the glider Petaurus breviceps and the glider appears to
have been more successful than Leadbeater's possum. The main concern for the species'
survival now are habitat fragmentation and the decline of suitable hollow-bearing trees
due to natural attrition, fire and the activities of timber harvesting.
Data on Biology and Ecology
Leadbeater's possum weighs 120 - 160 g (4.3 - 5.8 oz).
Habitat:
Moist tall open forest dominated by montane ash (mountain ash, alpine ash, shining gum)
containing large living or dead mountain ash with hollows in which to nest and an understory containing silver or mountain hickory
wattle acacia which supplies gum to supplement the Leadbeater's possum's main diet of invertebrates. The central highlands of Victoria
contain approximately 1700 sq km (660 sq mi) of montane ash forest, although suitable
habitat within this area is generally uncommon and is predicted to constitute only 6.7% of
this area (114 sq km/44 sq mi).
Age to Maturity:
2 years.
Birth Season:
Leadbeater's possum appears to breed in all months except January and February. The
most common birth months are May, June, October and November.
Birth Rate:
Litters of 1-2 are common.
Values of parameters that were input to population viability modeling (Lindenmayer & Possingham 1996):
Annual probability of 0 female young per female: 0.45
Annual probability of 1 female young per female: 0.30
Annual probability of 2 female young per female: 0.18
Annual probability of 3 female young per female: 0.06
Annual probability of 4 female young per female: 0.01
Early Development:
Young are weaned at about 3 months.
Adult females enforce the dispersal of their offspring when they are approximately 12
months old (10 months for female young; 15 months for male young).
Diet:
The Leadbeater's possum's diet consists mainly of insects that live on foliage and
under bark, supplemented by plant exudates and
sweet secretions produced by sap-sucking insects.
Social Organization:
The Leadbeater's possum's society is based on a matriarchal
mating system where individual females occupy nests in large hollow mountain ash trees and
actively defend a surrounding 1 - 3 hectare (2.5 - 7.5 acre) exclusive territory from other females. Mating is strictly monogamous and male partners assist females in defense
of territories. Additional adult males, as well as one or more generations of offspring,
may be tolerated in family groups by the breeding pairs. However, additional adult females
are not tolerated, and an associated higher female mortality results in a high male:female
ratio. The fact that it is the adult female, and not the males, that show most aggression
socially is uncharacteristic of most mammals. The members of the colony engage in mutual
grooming and seem to recognize each other by smell.
Age and Gender Distribution:
The male:female ratio is 3:1.
Mortality and Survival:
Values of parameters that were input to population viability modeling (Lindenmayer & Possingham 1996):
Annual probability of death:
Newborn: 0.0
Juvenile: 0.3
Adult: 0.3
Density and Range:
Within its distribution, Leadbeater's possum is usually found in a density of 1.5 - 3
individuals/hectare (0.6 - 1.2 individuals/acre). (Flannery 1990) Females defend an exclusive territory of 1 - 3 hectares (2.5 - 7.5 acres). Surveys
have shown approximately one reproductively active female per 6 hectares (15 acres) of
old-growth forest. (Lindenmayer
& Possingham 1996)
Values of parameters that were input to population viability modeling (Lindenmayer & Possingham 1996):
Minimum home range size of females in highest
quality habitat: 1 hectare (2.5 acres)
Minimum home range size of breeding females in old growth: 3.3 hectares (8.3 acres)
Maximum population density of females: 2 individuals/hectare (5 individuals/acre)
Minimum Viable Population:
Minimum Viable Population Density: 300 individuals/sq km (780 individuals/sq mi). (Silva & Downing 1994)
References
Burbidge & McKenzie 1989, Burton & Pearson 1987, Clark et al. 1991, Curry-Lindahl
1972, Flannery 1990, IUCN 1966, IUCN 1994, IUCN 1996, IUCN 2000,
IUCN 2003a, IUCN
2004, Kennedy 1992, Lindenmayer
et al. 1993, Lindenmayer &
Possingham 1996, Maxwell et al. 1996, Mus.
Vict., Nowak & Paradiso 1983, Oryx 1991, Terrambiente,
Unique
Austral. Anim.
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