KOALA
Phascolarctos cinereus
Koala at the Billabong Sanctuary, Townsville,
QLD.
The Koala Boy
This story was told long
ago by the aborigines in Australia. It explains why the koala must always
be treated with respect.
There was once a child whose parents died, and
who was left in the charge of cruel relatives who forbade him to drink
the water they had collected from the creek. The child was forced to eat
eucalyptus leaves, and he was thirsty most of the time.
One day, these relatives went off into the bush
for the day to hunt for food. By an oversight, they left their water vessels
in a place where the child could reach them. As soon as they were out of
sight, he took the opportunity to drink his fill.
Then, thinking of what might happen when they
returned, he had the foresight to take some full vessels and hang them
among the branches of a small tree. After that, he climbed into the tree
himself, and began to sing an ancient and magical song.
At once, the tree began to grow taller and taller
until the boy was high above the forest floor.
At dusk, his relatives returned, tired and thirsty.
They immediately looked for their water vessels, but they were nowhere
to be seen. Then one of them caught sight of the child sitting in the tree,
with the water vessels beside him.
The hunters became very angry, for they could
not reach the water, and they knew the boy had tricked them. But they were
clever people and spoke gently to the child, telling him they were sorry
they had treated him badly and that, if he were only to come down and bring
the water with him, they would be kind to him. The boy believed them and
made his way down to the ground.
But straightway his relatives set about him with
sticks and stones, beating him until his body was quite soft. Mad with
anger, they continue to beat him until at last a strange thing happened.
The boy began to change. He became shorter, stockier, and covered with
grey fur. He was a koala!
At once, he turned and ran up the tree again,
far out of reach of his tormentors.
They, in turn, began to chop the tree down, hacking
away at its trunk until it crashed to the ground, spilling the water vessels
as it did so. The water poured down, flooding across the forest floor as
a mighty creek, and the koala-boy disappeared for ever into the night.
Since that time, it has been forbidden for the
Aborigines to break the koala's bones when they kill it. Though they may
eat the animal, they may not skin it, and they must always treat its body
with respect. If they do not, there is a danger that all the water in the
land will dry up, and there will be a terrible drought.
Koala at the Australia Zoo, Beerwah, QLD.
Some history
1798, January 26: The 1st record of a koala being
seen by an European, John Price.
1803, August 21: The first detailed account of
a koala was published in the Sydney Gazette.
1816: The French naturalist de Blainwill gave
the koala its scientific name, Phascolarctos, from the Greek words for
'leather pouch' and 'bear'. Later, the German naturalist Goldfuss gave
it the specific name cinereus, meaning 'ash-coloured', after the color
of the original specimen.
The early settlers referred to koalas as sloths,
monkeys, bears, and even monkey bears, adopting the unfortunate practice
of transposing the names of animals which were already familiar to Europeans
to Australian lookalikes. The virtual absence of a tail, together with
their stocky build and their relatively long legs, gives the koalas a bear-like
appearance, and undoubtedly led to their being referred to as, "koala bears",
or, "native bears".
In their history of the koala, Tom Iredale and
Gilbert Whitley (1934) suggest that the common name "koala" was derived
from an Aboriginal dialect of eastern New South Wales. Ronald Strahan (1978)
lists cullewine, koolewong, colo, colah, koolah and koala as published
dialectal variations of the name in that region.
Scientific koala facts
Classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Diprotodontia
Family: Phascolarctidae
Genus: Phascolarctos
Species: Phascolarctos cinereus
Geographic Range
Australian. The koalas live in eastern Australia
and range from northern Queensland to southwestern Victoria. They have
been introduced to western Australia and nearby islands.
Physical Characteristics
Mass: 5 to 11 kg.
Koalas from the southern end of the range are
generally larger in size than their northern counterparts. In both areas
they exhibit sexual dimorphism with the males being larger. In the south,
males have an average head-body length of 78 cm and females 72 cm.
The koala's have a vestigial tail.
Average weights are:
-
in the south, males--11.8 kg, females--7.9 kg
-
in the north, males--6.5 kg, females 5.1 kg
Males are up to 50% heavier than females, have a
broader face, somewhat smaller ears, and a large chest gland.
Females have two mammae; and rather than a chest
gland, have a pouch that opens to the rear and extends upward and forward.
Koalas have dense, wooly fur that is gray to
brown on top and varies with geographic location. There is white on the
chin, chest and inner side of the forelimbs. The rump is often dappled
with white patches and the ears are fringed with long white hairs. The
coat is generally shorther and lighter in the north of range.
The paws are large, and both fore and hind feet
have five strongly clawed digits. On the forepaw the first and second digits
oppose the other three which enables the koala to grip branches as it climbs.
The first digit of the hind foot is short and greatly broadened while the
second and third digits are relatively small and partly syndactylous but
have separate claws.
Food Habits
Koalas are herbivorous feeding on both eucalypt and
non-eucalypt species. The animal has a highly specialized diet in which
they eat only 20 of the 350 species of eucalyptus
and prefer only 5 species: Eucalyptus viminalis and E. ovata are preferred
in the south, while E. punctata, E. camaldulensis and E. tereticornis are
the taste of the north. They feed at night.
The leaves are highly toxic. The animals get
around this by having a flora of bacteria in their stomachs that metabolize
the toxins of the leaves.
An adult koala can eat 500 grams daily. The koala
has adapted to cope with its high fiber, low protein diet. The cheek teeth
are reduced to a single premolar and four broad, highly cusped molars on
each jaw which finely grind the leaves for easier digestion. In addition
the koala's caecum is extremely large compared to its body size.
Reproduction
Females are sexually mature at two years of age.
Males are fertile at two years but usually don't mate until they reach
four simply because competition for females requires larger size.
Females are seasonally polyestrous, with an estrous
cycle of about 27-30 days, and usually breed once every year. T
he gestation period is 25-35 days with births
occurring in mid-summer (December-January). Litters generally consist of
only one young but twins have been reported.
The young weigh less than 0.5 grams when born,
and attach to one of the nipples in the pouch. Young have a pouch life
of 5-7 months, feeding on milk or predigested leaves that are nontoxic,
and are weaned at 6-12 months.
Toward the end of their pouch life the young
feed regularly on material passed through the mother's digestive tract.
Once the young begins to feed on leaves growth is rapid.
The young leaves the pouch after seven months
and is carried about on the mother's back. By eleven month's of age the
young is independent, but may continue to live close to the mother for
a few months.
Koalas may live past 10 years in the wild, and
there have been reports of life spans over 20 years in captivity.
Behavior
Koalas are polygynous and relatively sedentary. Because
of their low quality diet, koalas conserve energy by their behavior. They
are slow-moving and sleep up to 18 hours a day.
Adults occupy fixed home ranges, the males usually
1.5-3ha, females 0.5-1ha. For breeding males the home range will overlap
those of females as well as subadult and non-breeding males. During the
breeding season (October- February), adult males are very active at night
and move constantly through their range, both ejecting male rivals and
mating with any receptive females.
During the breeding season males use loud bellowing
calls, that consist of a series of harsh inhalations each followed by a
resonant, growling expiration. These calls advertise an individual's presence
and warn off other males. The only vocalization generally heard from females
and subadult males is a harsh wailing distress call given when harrassed
by adult males.
Copulation is brief genrally lasting less than
two minutes, and occurs in a tree. During mating the male will grasp the
back of the female's neck with his teeth.
Koalas are mainly nocturnal and completely arboreal.
They come to the ground occasionally to move to another food tree or to
lick up soil or gravel which aids in digestion.
Outside of the breeding season there is little
obvious social behavior. Koalas live in loose-knit groups if enough suitable
trees are present, but only one animal per tree. The koala is primarily
a solitary animal, although sometimes it lives in small harems led by a
single male. Koalas are extremely slow-moving animals and are relatively
defenseless.
Habitat
Koalas are arboreal, remaining mostly in the branches
of the eucalyptus trees, where they are able to feed and stay out of reach
of their predators. The koala is confined to eucalyptus forests below 600
m.
Biomes: temperate forest & rainforest
Economic Importance for Humans
Positive
In the early 20th century the koala was hunted
extensively for its warm, thick coat. However, they are now protected and
can no longer be hunted.
Negative
None noted.
Conservation
Status: no special status
The koala holds no special status although the
Environment Australia Biodiversity Group calls the koala lower risk--near
threatened (1996). Koalas were nearly exterminated at the turn of the century
because they were hunted for their fur, and because their environments
were destroyed by fires caused by humans. After 1927 as a result of public
outcry the koala became legally protected. Currently their main threat
is habitat destruction.
Management of the koala can be difficult. Populations
that are protected can reach such high numbers in an area that they destroy
the trees on which they feed. Often portions of populations have to be
relocated in order to reduce the number of individuals in a given area.
However, this is complicated by the shortage of suitable forest areas where
surplus animals can be released.
They are also threatened by the microorganism
Chlamydia psittaci, which can make them sterile.
Other Comments
Two interesting adaptations of the koala are:
-
Cheek pouches that allow the animal to store unchewed
food while moving to a safer or more protected location.
-
The koala cools itself by licking its arms and stretching
out as it rests in the trees (koalas have no sweat glands).
