TAXONOMY & NOMENCLATURE
(Houlden, et al., 1999)(Lee & Martin, 1988)(Takami, et al., 1998)
Describer (Date): (Goldfuss, 1817) Lipurus cinereus
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order:
Diprotodontia Family: Phascolarctidae Genus: Phascolarctos Species: Phascolarctos cinereus Subspecies:P. c adustus - Queensland P. c. cinereus - New South Wales P.c. victor -Victoria
Taxonomy
Family: only member of Phascolarctidae
Subspecies
Three subspecies have been described, but may just represent
gradual variation from northern Queensland to South Australia.
The boundaries of the subspecies are state boundaries, rather than
geographic.
DNA studies show do not show enough differentiation to support the
use of subspecies.
Nomenclature
"Koala" comes from Aboriginal word, meaning "no
drink"
Family Phascolarctidae has been around for 15 million years,
yielding several different types of koalas.
Widespread in the Pleistocene, extending into southwestern
Western Australia.
Closest living relative: the wombat
DISTRIBUTION & HABITAT
(Martin, 2001)
Koala distribution. From Sharp, 1995
Distribution
Eastern and southeastern Australia: From Cooktown (Queensland) to South
Australia.
Disjunct distribution (isolated pockets) across range.
Have been introduced into the islands off of the southern coast and
Western Australia (outside of natural distribution).
Habitat:
Confined to eucalyptus forests, but habitat varies regionally; wet
montane forests, dry woodlands, vine thickets.
Greatest preference for trees growing in highly fertile soils.
Prefer larger trees.
PHYSICAL CHARACTERISTICS
(Nowak, 1999)
Body Weight: 4 - 15 kg (9 - 33 lbs), averaging 11 kg
(24 lbs) for males and 8 kg (17.6 lbs) for females;
animals significantly smaller in northern part of range. Head/Body Length:600 - 850 mm (23.6 - 33.5 in) Tail Length:vestigial, hidden by fur.
General
Teddy bear like in shape, with small compact body, short limbs, and
large rounded ears.
Short, dense, woolly fur. Overall light gray, white under parts, rump
dappled with white. Ears fringed with white hair. Black, leathery
nose.
Marsupial pouch, which opens towards the rear.
Forefoot: First two toes opposable to other three. Hind foot: First toe
opposable to other four. Second and third toes conjoined by skin. All
toes with long, sharp claws except first digit of hind foot.
Sexual Dimorphism
Males: 50% heavier, wider face, smaller ears, large sternal gland on
chest (females do not have this gland).
Females: rear-opening pouch on underside, two teats.
Other Physical Characteristics
Teeth specialized for chewing fibrous leaves -broad, high-cusped cheek
teeth
Cheek pouches.
Small brain: 0.2% body weight; one of smallest in marsupials.
Primarily nocturnal, although some activities may occur during the day.
Sleep up to 20 hours/day. Less than 4 hours/day is spent foraging and
resting. The remainder (<1%) is spend moving, grooming, or
interacting socially.
Low energy output is necessary for animal that specializes on such a
low energy diet.
Foraging is done in 4 - 6 sessions per day, each lasting about 20
minutes to 2 hours.
Home Range/Territory
Home Range
Average home range size on French Island: males 1.70 ha (4
acres), females 1.18 ha (3 acres) (Mitchell,
1990b). Home range sizes reported in the literature vary greatly
due to different methods used.
Home range size, and population density vary with habitat:
Male's home range up to 100 ha (247 acres) in semi-arid, less
productive forest; population density much lower as well (Martin, 2001).
Tend to stay in the same home range for many years, often using
the same trees.
Home range of a dominant male may overlap with that of several
females, and subadult or subordinate males.
Territorial Behavior
Level of territoriality is unclear. Some authors report no
evidence of territoriality; others call them highly territorial
(AKF, 2003; Mitchell, 1990b).
Aggression:
Most often occurs when one animal enters an occupied
tree. Depending on level of dominance, either invader
or resident can be the aggressor.
Male-male: One usually ends up leaving, but will not be
chased beyond the base of the tree. Usually seen in
males at least 4 years old.
Male-female: Male is the aggressor, and attacks or tries
to copulate with female. Female does not flee, but
responds defensively.
Tree sharing occurs occasionally by male-male, male-female,
and female-female pairs.
Social Groups
Dominance hierarchy among males: Subordinates recognize
dominants and may retreat even before any overt aggression is shown.
Solitary; tend to avoid one another. 86-89% (breeding season) to
93-96% (non-breeding) time spent alone.
Tend to occur in clusters of overlapping home ranges = stable
breeding groups. Consists of one dominant male and several females and
subordinate males.
Communication
Vocalization
Bellowing
"Consists of a series of harsh inhalations each followed by a
resonant growling expiration." (Martin, 2001)
Both sexes, but most often by adult males.
More common during mating season.
More frequent at night.
To attract mates, and to warn off other males. May assist in
maintenance of spacing between individuals.
The call is often answered by other males in the area.
Encounter calls: Mitchell (1990a) described four types, in
addition to bellowing. Response to aggressive encounters.
Squawks: short, harsh
Snarls: longer (up to 2 seconds), atonal to moderately
tonal
Screams: high pitched, sound travels farther
Wails: Longer than screams, similar to wail of domestic cat
By females or young in distress.
Olfaction/Scent Marking
Sternal gland used to mark trees, possibly to mark territorial
boundary; most frequent during breeding season; by males at least 4
years old.
Occasional marking with drops of urine has been observed by both sexes;
on or at the base of trees. The exact meaning of this is unclear.
Play
By young animals
Solitary or with another
Climbing and jumping or chasing one another
Locomotion
Arboreal, but must travel on the ground to move to another tree. Travel
on all fours.
Sedentary, but can move relatively quickly on the ground or up a tree
if necessary.
Males tend to move to new trees more often than females.
Climb (a) by bounding up rapidly, using hind legs to push them up or
(b) slowly, using arm, then opposite hind limb. Recurved claws and
opposable digits help them grasp trunks and branches.
Browsers. Eat about 500 g (1.1 lb) of leaves per day.
Prefer leaves of only a few species of Eucalyptus tree,
which vary population to population. But up to 30 species of
Eucalyptus are important in the diet. (There are 500+ species of Eucalyptus
in Australia). Example of preferred species:
Southern coastal Australia: E. viminalis and E. ovata
Inland, New South Wales, and Queensland: E camaldulensis, E.
tereticornis, E. microcorys, E. propinqua, and E. punctata
Seasonal changes in species preference -may cosume more of one
preferred species over another during a particular time of year.
So particular about food choice that they have been known to
completely defoliate and kill trees of one species, while leaving
other nearby species untouched. Sometimes individual trees of a given
species are preferred.
Occasionally supplement diet with trees other than Eucalyptus,
including exotics, such as Acacia, Leptospermum, and Melaleuca.
But these are only a small percentage of total diet.
Foraging behavior
Pulls a branch to its nose before eating; smell may play a
role in identifying preferred species.
May store leaves in cheek pouches for later consumption.
Occasionally eat soil or gravel on the ground to aid in
digestion.
Digestion
Eucalyptus leaves high in indigestible fiber, high in toxins
(terpenes and phenolics) and low in nutrients.
Some toxins are processed and eliminated by the liver.
Specialized teeth assist in chewing leaves into paste.
Stomach has cardiogastric gland, which increases acid and
enzyme production. Wombats are the only other marsupial that
has this gland.
Microbial fermentation in the caecum, which is largest of any
mammal in proportion to body size.
Water: Obtain water exclusively from leaves except when very hot
and dry.
REPRODUCTION & DEVELOPMENT
(Gordon et al., 1990)(Lee & Martin, 1988)(Martin, 2001)
(Martin & Handasyde, 1990)(Mitchell, 1990a)(White & Kunst 1990)
Courtship
Males polygynous (mate with more than one female).
Males may not be able to detect when a female is in estrus and will
copulate any time during the breeding season.
Copulation usually forced by male; female tries to back away and makes
defensive vocalizations ("snarls, weak bellows, squawking,
screaming").
Dominant male often chases off subordinate male who tries to mate with
a nearby female.
Reproduction
Breeding: October - November (spring)
Inter-birth interval: once every 1 - 2 years.
Females are seasonally polyestrus (repeated estrus cycles during
the breeding season).
Gestation: Approximately 35 days
Life Stages
Birth
Birthing season: most births occur December - February (summer).
Litter size: one, rarely two
Birth weight: less than 0.5 g]
Size: about 2 cm long
As with all marsupials, newborn is blind, very underdeveloped, and
fetal-like. Forelimbs and claws more developed, which assist in
crawling. Senses of touch and smell well developed.
Newborn crawls into pouch unassisted by mother, and attaches itself to
one of the teats.
Infant (< 1 year old)
Young also called "joey".
Develops in pouch for 6 months, and then starts making short excursions
outside of pouch.
Once outside of pouch, young rides on mother's back.
Starts feeding on paste of partially digested leaves that is excreted
by mother ("pap"). This may give the young microorganisms it
needs to digest eucalyptus leaves. Continues drinking milk for up to a
year.
Starts eating leaves in addition to pap and milk.
Juvenile/Subadult
Independent of mother: 12-24 months of age, when next joey is
born; remains close by for several more months.
Males tend to disburse from natal home range, but females tend to set
up home range nearby.
Females will occasionally accept an unrelated joey to care for.
Adult
Sexual maturity: Females sexually mature at approximately 6 kg (
13 lbs), 2 - 3 years of age. Males sexually mature at 2 years, but
mating success is low until 4th or 5th year.
Sternal gland begins to develop in males at about 1.5 - 3 years
of age.
Longevity
Captivity: Up to 18 years
Wild: 14+ years under ideal conditions. Much shorter near human
habitation.
Mortality
Main causes of mortality: being hit by cars, or preyed on by
dogs/dingoes. Most vulnerable when on ground.
Drought: reduces availability of forage, causing death due to
starvation or poor nutrition.
1870-1890: Introduced onto Phillip and French Islands
(Victoria); French Island population (Chlamydia-free)
prospered, and became overpopulated by the 1920's.
1920's: Official translocation program began; moved
individuals from French Island to Victorian islands.
1940's: Populations translocated to mainland Victoria
and South Australia.
Present: Despite high infection rate of Chlamydia,
many populations are doing well, but useable habitat is
decreasing rapidly, resulting in overpopulation in
some areas. This may lead to decimation of food sources due
to over browsing.
Culling is not supported by the community, so
translocation may be only solution to avoid starvation.
Conservation genetics
DNA studies show low variability in the Victoria and South
Australia populations.
Most of these probably originate from French Island
translocations. The French Island population was started with
only a few individuals from the mainland.
Could lead to inbreeding problems.
South Gippsland populations may be only endemics left in Victoria.
Threats to survival
Over hunting: Heavily hunted for their pelts in the 19th and
20th centuries. More than two million skins were exported in 1924.
Habitat destruction and fragmentation: Due to development, wild
fires. Habitat is not currently protected.
Extended drought
Hit by cars, mostly during breeding season when males are moving
about more frequently.
Drowning in swimming pools.
Predation by dogs, dingoes, feral cats, feral foxes, owls, and
wedge-tail eagles. Young most vulnerable.
Disease: Most common - Chlamydia, which may cause
infertility and sometimes death.
Atlas
of New South Wales wildlife - Shows recorded sightings of plants,
mammals, birds, reptiles, amphibians and endangered invertebrates in
New South Wales. Generates a map of user defined parameters.
