The
koala (
Phascolarctos cinereus, or, inaccurately,
koala bear[a]) is an
arboreal herbivorous marsupial native to
Australia. It is the only
extant representative of the family
Phascolarctidae and its closest living relatives are the
wombats. The koala is found in coastal areas of the mainland's eastern and southern regions, inhabiting
Queensland,
New South Wales,
Victoria, and
South Australia.
It is easily recognisable by its stout, tailless body and large head
with round, fluffy ears and large, spoon-shaped nose. The koala has a
body length of 60–85 cm (24–33 in) and weighs 4–15 kg (9–33 lb).
Pelage
colour ranges from silver grey to chocolate brown. Koalas from the
northern populations are typically smaller and lighter in colour than
their counterparts further south. These populations possibly are
separate
subspecies, but this is disputed.
Koalas typically inhabit open
eucalypt
woodlands, and the leaves of these trees make up most of their diet.
Because this eucalypt diet has limited nutritional and caloric content,
koalas are largely
sedentary and sleep up to 20 hours a day. They are asocial animals, and
bonding exists only between mothers and dependent offspring. Adult males
communicate with loud bellows that intimidate rivals and attract mates. Males mark their presence with secretions from
scent glands located on their chests. Being marsupials, koalas give birth to underdeveloped young that crawl into their mothers'
pouches, where they stay for the first six to seven months of their lives. These young koalas, known as
joeys, are fully
weaned around a year old. Koalas have few natural predators and parasites, but are threatened by various
pathogens, such as
Chlamydiaceae bacteria and the
koala retrovirus, as well as by
bushfires and droughts.
Koalas were hunted by
indigenous Australians and depicted in
myths and
cave art
for millennia. The first recorded encounter between a European and a
koala was in 1798, and an image of the animal was published in 1810 by
naturalist
George Perry. Botanist
Robert Brown wrote the first detailed scientific
description of the koala in 1814, although his work remained unpublished for 180 years. Popular artist
John Gould
illustrated and described the koala, introducing the species to the
general British public. Further details about the animal's biology were
revealed in the 19th century by several English scientists. Because of
its distinctive appearance, the koala is recognised worldwide as a
symbol of Australia. Koalas are listed as
Vulnerable by the
International Union for Conservation of Nature.
[1] The Australian government similarly lists specific populations in Queensland and New South Wales as Vulnerable.
[4] The animal was hunted heavily in the early 20th century for its fur, and large-scale
cullings in Queensland resulted in a public outcry that initiated a movement to protect the species.
Sanctuaries were established, and
translocation efforts moved to new regions koalas whose habitat had become fragmented or reduced. The biggest threat to their existence is
habitat destruction caused by agriculture and
urbanisation.
Etymology
The word koala comes from the
Dharug gula. Although the vowel 'u' was originally written in the
English orthography as "oo" (in spellings such as
coola or
koolah), it was changed to "oa", possibly in error.
[5] Because of the koala's supposed resemblance to a
bear, it was often miscalled the koala bear, particularly by early settlers.
[6] The
generic name,
Phascolarctos, is derived from the
Greek words
phaskolos "pouch" and
arktos "bear". The
specific name,
cinereus, is
Latin for "ash coloured".
[7]
Taxonomy and evolution
The koala was given its generic name
Phascolarctos in 1816 by French zoologist
Henri Marie Ducrotay de Blainville,
[9] who would not give it a specific name until further review. In 1819, German zoologist
Georg August Goldfuss gave it the
binomial Lipurus cinereus. Because
Phascolarctos was published first, according to the
International Code of Zoological Nomenclature, it has
priority as the official name of the genus.
[10] French naturalist
Anselme Gaëtan Desmarest proposed the name
Phascolartos fuscus
in 1820, suggesting that the brown-coloured versions were a different
species than the grey ones. Other names suggested by European authors
included
Marodactylus cinereus by Goldfuss in 1820,
P. flindersii by
René Primevère Lesson in 1827, and
P. koala by
John Edward Gray in 1827.
[2]
The koala is classified with
wombats (family Vombatidae) and several extinct families (including
marsupial tapirs,
marsupial lions and
giant wombats) in the suborder
Vombatiformes within the order
Diprotodontia.
[11] The Vombatiformes are a
sister group to a
clade that includes
macropods (
kangaroos and
wallabies) and
possums.
[12] The ancestors of vombatiforms were likely
arboreal,
[8] and the koala's
lineage was possibly the first to branch off around 40 million years ago during the
Eocene.
[13]
Reconstructions of the ancient koalas Nimiokoala (larger), and Litokoala (smaller), from the Miocene Riversleigh Fauna
The modern koala is the only
extant member of
Phascolarctidae, a family that once included several genera and species. During the
Oligocene and
Miocene, koalas lived in
rainforests and had less specialised diets.
[14] Some species, such as the
Riversleigh rainforest koala (
Nimiokoala greystanesi) and some species of
Perikoala, were around the same size as the modern koala, while others, such as species of
Litokoala, were one-half to two-thirds its size.
[15]
Like the modern species, prehistoric koalas had well developed ear
structures which suggests that long-distance vocalising and sedentism
developed early.
[14] During the Miocene, the Australian continent began drying out, leading to the decline of rainforests and the spread of open
Eucalyptus woodlands. The genus
Phascolarctos split from
Litokoala in the late Miocene
[14][16] and had several adaptations that allowed it to live on a specialised eucalyptus diet: a shifting of the
palate towards the front of the skull; larger
molars and
premolars; smaller
pterygoid fossa;
[14] and a larger
gap between the molar and the
incisor teeth.
[17]
During the
Pliocene and
Pleistocene, when Australia experienced changes in climate and vegetation, koala species grew larger.
[15] P. cinereus may have emerged as a dwarf form of the
giant koala (
P. stirtoni). The reduction in the size of large mammals has been seen as a common phenomenon worldwide during the
late Pleistocene, and several Australian mammals, such as the
agile wallaby, are traditionally believed to have resulted from this dwarfing. A 2008 study questions this hypothesis, noting that
P. cinereus and
P. stirtoni were
sympatric during the middle to late Pleistocene, and possibly as early as the Pliocene.
[18] The fossil record of the modern koala extends back at least to the middle Pleistocene.
[19]
Genetics and variations
Traditionally, three distinct
subspecies have been recognised: the
Queensland koala (
P. c. adustus,
Thomas 1923), the
New South Wales koala (
P. c. cinereus, Goldfuss 1817), and the
Victorian koala (
P. c. victor,
Troughton 1935). These forms are distinguished by
pelage
colour and thickness, body size, and skull shape. The Queensland koala
is the smallest of the three, with shorter, silver fur and a shorter
skull. The Victorian koala is the largest, with shaggier, brown fur and a
wider skull.
[20][21] The boundaries of these variations are based on
state borders, and their status as subspecies is disputed. A 1999 genetic study suggests that the variations represent differentiated
populations with limited
gene flow between them, and that the three subspecies comprise a single
evolutionarily significant unit.
[21] Other studies have found that koala populations have high levels of
inbreeding and low
genetic variation.
[22][23] Such low
genetic diversity may have been a characteristic of koala populations since the late Pleistocene.
[24]
Rivers and roads have been shown to limit gene flow and contribute to
the genetic differentiation of southeast Queensland populations.
[25] In April 2013, scientists from the
Australian Museum and
Queensland University of Technology announced they had
fully sequenced the koala
genome.
[26]
Description
The koala is a stocky animal with a large head and
vestigial or non-existent tail.
[27][28] It has a body length of 60–85 cm (24–33 in) and a weight of 4–15 kg (9–33 lb),
[28] making it among the largest arboreal marsupials.
[29] Koalas from Victoria are twice as heavy as those from Queensland.
[20] The species is
sexually dimorphic, with males 50% larger than females. Males are further distinguished from females by their more curved noses
[29] and the presence of chest glands, which are visible as hairless patches.
[30] As in most marsupials, the male koala has a
bifurcated penis,
[31] and the female has two lateral
vaginas and two separate
uteri.
[27] The male's
penile sheath contains naturally occurring
bacteria that play an important role in
fertilisation.
[32] The female's
pouch opening is tightened by a
sphincter that keeps the young from falling out.
[33]
The pelage of the koala is thicker and longer on the back, and
shorter on the belly. The ears have thick fur on both the inside and
outside.
[29] The back fur colour varies from light grey to chocolate brown.
[27] The belly fur is whitish; on the rump it is dappled whitish, and darker at the back.
[28]
The koala has the most effective insulating back fur of any marsupial
and is highly resilient to wind and rain, while the belly fur can
reflect solar radiation.
[34] The koala's curved, sharp claws are well adapted for climbing trees. The large forepaws have two
opposable digits
(the first and second, which are opposable to the other three) that
allow them to grasp small branches. On the hindpaws, the second and
third digits are
fused, a typical condition for members of the Diprotodontia, and the attached claws (which are still separate) are used for grooming.
[35] As in humans and other
primates, koalas have
friction ridges on their paws.
[36]
The animal has a sturdy skeleton and a short, muscular upper body with
proportionately long upper limbs that contribute to its climbing and
grasping abilities. Additional climbing strength is achieved with thigh
muscles that attach to the
shinbone lower than other animals.
[37] The koala has a
cartilaginous pad at the end of the spine that may make it more comfortable when it perches in the fork of a tree.
[33]
The koala has one of the smallest
brains in proportion to body weight of any mammal,
[38] being 60% smaller than that of a typical
diprotodont, weighing only 19.2 g (0.68 oz).
[39] The brain's surface is fairly smooth, typical for a "
primitive" animal.
[40] It occupies only 61% of the
cranial cavity[38] and is pressed against the inside surface by
cerebrospinal fluid.
The function of this relatively large amount of fluid is not known,
although one possibility is that it acts as a shock absorber, cushioning
the brain if the animal falls from a tree.
[40]
The koala's small brain size may be an adaptation to the energy
restrictions imposed by its diet, which is insufficient to sustain a
larger brain.
[38]
Because of its small brain, the koala has a limited ability to perform
complex, unfamiliar behaviours. For example, when presented with plucked
leaves on a flat surface, the animal cannot adapt to the change in its
normal feeding routine and will not eat the leaves.
[41] The koala's
olfactory senses are normal, and it is known to sniff the oils of individual branchlets to assess their edibility.
[38] Its nose is fairly large and covered in leathery skin. Its round ears provide it with good hearing,
[33] and it has a well-developed
middle ear.
[14] A koala's vision is not well developed,
[33] and its relatively small eyes are unusual among marsupials in that the pupils have vertical slits.
[29] Koalas make use of a novel vocal organ to produce low-pitched sounds (see
social spacing, below). Unlike typical mammalian
vocal cords, which are folds in the larynx, these organs are placed in the velum (
soft palate) and are called velar vocal cords.
[42]
The koala has several adaptations for its eucalypt diet, which is of low nutritive value, of high toxicity, and high in
dietary fibre.
[43] The animal's
dentition consists of the incisors and
cheek teeth
(a single premolar and four molars on each jaw), which are separated by
a large gap (a characteristic feature of herbivorous mammals). The
incisors are used for grasping leaves, which are then passed to the
premolars to be snipped at the
petiole before being passed to the highly
cusped molars, where they are shredded into small pieces.
[44] Koalas may also store food in their
cheek pouches before it is ready to be chewed.
[45]
The partially worn molars of middle-aged koalas are optimal for
breaking the leaves into small particles, resulting in more efficient
stomach digestion and nutrient absorption in the small intestine,
[46] which digests the eucalyptus leaves to provide most of the animal's energy.
[44] A koala sometimes
regurgitates the food into the mouth to be chewed a second time.
[47]
Unlike kangaroos and eucalyptus-eating possums, koalas are
hindgut fermenters, and their digestive retention can last for up to 100 hours in the wild, or up to 200 hours in captivity.
[44] This is made possible by the extraordinary length of their
caecum—200 cm (80 in) long and 10 cm (4 in) in diameter—the largest proportionally of any animal.
[48]
Koalas can select which food particles to retain for longer
fermentation and which to pass through. Large particles typically pass
through more quickly, as they would take more time to digest.
[44]
While the hindgut is proportionally larger in the koala than in other
herbivores, only 10% of the animal's energy is obtained from
fermentation. Since the koala gains a low amount of energy from its
diet, its
metabolic rate is half that of a typical mammal,
[43] although this can vary between seasons and sexes.
[44]
The koala conserves water by passing relatively dry faecal pellets high
in undigested fibre, and by storing water in the caecum.
[46]
Ecology and behaviour
The koala's geographic range covers roughly 1,000,000 km
2 (390,000 sq mi), and 30
ecoregions.
[49]
It extends throughout eastern and southeastern Australia, encompassing
northeastern, central and southeastern Queensland, eastern New South
Wales, Victoria, and southeastern
South Australia. The koala was
introduced near
Adelaide and on several islands, including
Kangaroo Island and
French Island.
[1] The population on
Magnetic Island represents the northern limit of its range.
[49] Fossil evidence shows that the koala's range stretched as far west as southwestern
Western Australia during the late Pleistocene. They were likely driven to extinction in these areas by environmental changes and hunting by
indigenous Australians.
[50]
In Queensland, koalas are unevenly distributed and uncommon
except in the southeast, where they are numerous. In New South Wales,
they are abundant only in
Pilliga, while in Victoria they are common nearly everywhere. In South Australia, koalas were
extirpated by 1920 and subsequently reintroduced.
[1] Koalas can be found in habitats ranging from relatively open
forests to
woodlands, and in climates ranging from
tropical to cool
temperate.
[29] In
semi-arid climates, they prefer
riparian habitats, where nearby streams and creeks provide refuge during times of drought and extreme heat.
[51]
Foraging and activities
Koalas are
herbivorous, and while most of their diet consists of eucalypt leaves, they can be found in trees of other genera, such as
Acacia,
Allocasuarina,
Callitris,
Leptospermum, and
Melaleuca.
[52] They are able to digest the toxins present in eucalyptus leaves due to their production of
cytochrome P450, which breaks down these poisons in the
liver[53][54]. Though the foliage of over 600 species of
Eucalyptus is available, the koala shows a strong preference for around 30.
[55] They tend to choose species that have a high
protein content and low proportions of fibre and
lignin.
[46] The most favoured species are
Eucalyptus microcorys,
E. tereticornis, and
E. camaldulensis, which, on average, make up more than 20% of their diet.
[56] Despite its reputation as a fussy eater, the koala is more
generalist than some other marsupial species, such as the
greater glider. Since eucalypt leaves have a high water content, the koala does not need to drink often;
[52]
its daily water turnover rate ranges from 71 to 91 ml/kg of body
weight. Although females can meet their water requirements from eating
leaves, larger males require additional water found on the ground or in
tree hollows.
[46]
When feeding, a koala holds onto a branch with hindpaws and one forepaw
while the other forepaw grasps foliage. Small koalas can move close to
the end of a branch, but larger ones stay near the thicker bases.
[57] Koalas consume up to 400 grams (14 oz) of leaves a day, spread over four to six feeding sessions.
[58] Despite their adaptations to a low-energy lifestyle, they have meagre
fat reserves and need to feed often.
[59]
Because they get so little energy from their diet, koalas must limit their
energy use and sleep 20 hours a day;
[60] only 4 hours a day are spent in active movement.
[61]
They are predominantly active at night and spend most of their waking
hours feeding. They typically eat and sleep in the same tree, possibly
for as long as a day.
[62]
On very hot days, a koala may climb down to the coolest part of the
tree which is cooler than the surrounding air. The koala hugs the tree
to lose heat without panting.
[63][64] On warm days, a koala may rest with its back against a branch or lie on its stomach or back with its limbs dangling.
[60] During cold, wet periods, it curls itself into a tight ball to conserve energy.
[62]
On windy days, a koala finds a lower, thicker branch on which to rest.
While it spends most of the time in the tree, the animal descends to the
ground to move to another tree, walking on all fours.
[60] The koala usually grooms itself with its hindpaws, but sometimes uses its forepaws or mouth.
[65]
Social spacing
Koalas are asocial animals and spend just 15 minutes a day on social behaviours. In Victoria,
home ranges are small and have extensive overlap, while in central Queensland they are larger and overlap less.
[66]
Koala society appears to consist of "residents" and "transients", the
former being mostly adult females and the latter males. Resident males
appear to be
territorial and
dominate others with their larger body size.
[67] Alpha males
tend to establish their territories close to breeding females, while
younger males are subordinate until they mature and reach full size.
[68] Adult males occasionally venture outside their home ranges; when they do so, dominant ones retain their status.
[66]
When a male enters a new tree, he marks it by rubbing his chest gland
against the trunk or a branch; males have occasionally been observed to
dribble urine on the trunk. This scent-marking behaviour probably serves
as communication, and individuals are known to sniff the base of a tree
before climbing.
[69] Scent marking is common during aggressive encounters.
[70]
Chest gland secretions are complex chemical mixtures—about 40 compounds
were identified in one analysis—that vary in composition and
concentration with the season and the age of the individual.
[71]
Adult males communicate with loud bellows—low pitched sounds that consist of snore-like inhalations and
resonant exhalations that sound like growls.
[72] These sounds are thought to be generated by unique vocal organs found in koalas.
[42] Because of their low
frequency, these bellows can travel far through air and vegetation.
[73] Koalas may bellow at any time of the year, particularly during the
breeding season, when it serves to attract females and possibly intimidate other males.
[74] They also bellow to advertise their presence to their neighbours when they enter a new tree.
[73] These sounds signal the male's actual body size, as well as exaggerate it;
[75] females pay more attention to bellows that originate from larger males.
[76]
Female koalas bellow, though more softly, in addition to making
snarls, wails, and screams. These calls are produced when in distress
and when making defensive threats.
[72]
Young koalas squeak when in distress. As they get older, the squeak
develops into a "squawk" produced both when in distress and to show
aggression. When another individual climbs over it, a koala makes a low
grunt with its mouth closed. Koalas make numerous facial expressions.
When snarling, wailing, or squawking, the animal curls the upper lip and
points its ears forward. During screams, the lips retract and the ears
are drawn back. Females bring their lips forward and raise their ears
when agitated.
[77]
Agonistic behaviour
typically consists of squabbles between individuals climbing over or
passing each other. This occasionally involves biting. Males that are
strangers may wrestle, chase, and bite each other.
[78]
In extreme situations, a male may try to displace a smaller rival from a
tree. This involves the larger aggressor climbing up and attempting to
corner the victim, which tries either to rush past him and climb down or
to move to the end of a branch. The aggressor attacks by grasping the
target by the shoulders and repeatedly biting him. Once the weaker
individual is driven away, the victor bellows and marks the tree.
[79] Pregnant and
lactating females are particularly aggressive and attack individuals that come too close.
[78] In general, however, koalas tend to avoid energy-wasting aggressive behaviour.
[68]
Reproduction and development
Koalas are seasonal breeders, and births take place from the middle
of spring through the summer to early autumn, from October to May.
Females in
oestrus tend to hold their heads further back than usual and commonly display
tremors and
spasms.
However, males do not appear to recognise these signs, and have been
observed to mount non-oestrous females. Because of his much larger size,
a male can usually force himself on a female, mounting her from behind,
and in extreme cases, the male may pull the female out of the tree. A
female may scream and vigorously fight off her suitors, but will submit
to one that is dominant or is more familiar. The bellows and screams
that accompany matings can attract other males to the scene, obliging
the incumbent to delay mating and fight off the intruders. These fights
may allow the female to assess which is dominant.
[80] Older males usually have accumulated scratches, scars, and cuts on the exposed parts of their noses and on their eyelids.
[81]
The koala's
gestation period lasts 33–35 days,
[82] and a female gives birth to a single
joey (although twins occur on occasion). As with all marsupials, the young are born while at the
embryonic stage,
weighing only 0.5 g (0.02 oz). However, they have relatively
well-developed lips, forelimbs, and shoulders, as well as functioning
respiratory,
digestive, and
urinary systems. The joey crawls into its mother's pouch to continue the rest of its development.
[83] Unlike most other marsupials, the koala does not clean her pouch.
[84]
A female koala has two teats; the joey attaches itself to one of them and suckles for the rest of its pouch life.
[83]
The koala has one of the lowest milk energy production rates in
relation to body size of any mammal. The female makes up for this by
lactating for as long as 12 months.
[85] At seven weeks of age, the joey's head grows longer and becomes proportionally large,
pigmentation begins to develop, and its sex can be determined (the
scrotum
appears in males and the pouch begins to develop in females). At 13
weeks, the joey weighs around 50 g (1.8 oz) and its head has doubled in
size. The eyes begin to open and fine fur grows on the forehead,
nape, shoulders, and arms. At 26 weeks, the fully furred animal resembles an adult, and begins to poke its head out of the pouch.
[86]
As the young koala approaches six months, the mother begins to
prepare it for its eucalyptus diet by predigesting the leaves, producing
a faecal pap that the joey eats from her
cloacum.
The pap is quite different in composition from regular faeces,
resembling instead the contents of the caecum, which has a high
concentration of bacteria. Eaten for about a month, the pap provides a
supplementary source of protein at a transition time from a milk to a
leaf diet.
[87]
The joey fully emerges from the pouch for the first time at six or
seven months of age, when it weighs 300–500 g (11–18 oz). It explores
its new surroundings cautiously, clinging to its mother for support. By
nine months, it weighs over 1 kg (2.2 lb) and develops its adult fur
colour. Having permanently left the pouch, it rides on its mother's back
for transportation, learning to climb by grasping branches.
[88]
Gradually, it spends more time away from its mother, and at 12 months
it is fully weaned, weighing around 2.5 kg (5.5 lb). When the mother
becomes pregnant again, her bond with her previous offspring is
permanently severed. Newly weaned young are encouraged to disperse by
their mothers' aggressive behaviour towards them.
[89]
A young joey, preserved at Port Macquarie Koala Hospital
Females become
sexually mature
at about three years of age and can then become pregnant; in
comparison, males reach sexual maturity when they are about four years
old,
[90] although they can produce sperm as early as two years.
[89]
While the chest glands can be functional as early as 18 months of age,
males do not begin scent-marking behaviours until they reach sexual
maturity.
[71]
Because the offspring have a long dependent period, female koalas
usually breed in alternate years. Favourable environmental factors, such
as a plentiful supply of high-quality food trees, allow them to
reproduce every year.
[91]
Health and mortality
Koalas may live from 13 to 18 years in the wild. While female koalas
usually live this long, males may die sooner because of their more
hazardous lives.
[92]
Koalas usually survive falls from trees and immediately climb back up,
but injuries and deaths from falls do occur, particularly in
inexperienced young and fighting males.
[93]
Around six years of age, the koala's chewing teeth begin to wear down
and their chewing efficiency decreases. Eventually, the cusps disappear
completely and the animal will die of starvation.
[94]
Koalas have few predators;
dingos and large
pythons may prey on them, while
birds of prey (such as
powerful owls and
wedge-tailed eagles) are threats to young. They are generally not subject to external
parasites, other than
ticks in coastal areas. Koalas may also suffer
mange from the
mite Sarcoptes scabiei, and
skin ulcers from the bacterium
Mycobacterium ulcerans, but neither is common. Internal parasites are few and largely harmless.
[93] These include the
tapeworm Bertiella obesa, commonly found in the intestine, and the
nematodes Marsupostrongylus longilarvatus and
Durikainema phascolarcti, which are infrequently found in the lungs.
[95]
In a three-year study of almost 600 koalas admitted to the Australian
Zoo Wildlife Hospital in Queensland, 73.8% of the animals were infected
with at least one species of the parasitic
protozoal genus
Trypanosoma, the most common of which was
T. irwini.
[96]
Koalas can be subject to
pathogens such as
Chlamydiaceae bacteria,
[93] which can cause
keratoconjunctivitis,
urinary tract infection, and
reproductive tract infection.
[97] Such infections are widespread on the mainland, but absent in some island populations.
[98] The
koala retrovirus (KoRV) may cause koala immune deficiency syndrome (KIDS) which is similar to
AIDS in humans.
Prevalence
of KoRV in koala populations suggests a trend spreading from the north
to the south of Australia. Northern populations are completely infected,
while some southern populations (including Kangaroo Island) are free.
[99]
The animals are vulnerable to
bushfires due to their slow movements and the flammability of eucalypt trees.
[100]
The koala instinctively seeks refuge in the higher branches, where it
is vulnerable to intense heat and flames. Bushfires also fragment the
animal's habitat, which restricts their movement and leads to population
decline and loss of genetic diversity.
[101] Dehydration and overheating can also prove fatal.
[102] Consequently, the koala is vulnerable to the
effects of climate change.
Models of
climate change in Australia predict warmer and drier climates, suggesting that the koala's range will shrink in the east and south to more
mesic habitats.
[103] Droughts also affect the koala's well-being. For example, a severe
drought in 1980 caused many
Eucalyptus
trees to lose their leaves. Subsequently, 63% of the population in
southwestern Queensland died, especially young animals that were
excluded from prime feeding sites by older, dominant koalas, and
recovery of the population was slow.
[41]
Later, this population declined from an estimated mean population of
59,000 in 1995 to 11,600 in 2009, a reduction attributed largely to
hotter and drier conditions resulting from droughts in most years
between
2002 and 2007.
[104] Another predicted negative outcome of climate change is the effect of elevations in
atmospheric CO2 levels on the koala's food supply: increases in CO
2 cause
Eucalyptus trees to reduce protein and increase
tannin concentrations in their leaves, reducing the quality of the food source.
[105]
Human relations
History
George Perry's illustration in his 1810 Arcana was the first published image of the koala.
The first written reference of the koala was recorded by John Price, servant of
John Hunter, the
Governor of New South Wales. Price encountered the "cullawine" on 26 January 1798, during an expedition to the
Blue Mountains,
[106] although his account was not published until nearly a century later in
Historical Records of Australia.
[107] In 1802, French-born explorer
Francis Louis Barrallier
encountered the animal when his two Aboriginal guides, returning from a
hunt, brought back two koala feet they were intending to eat.
Barrallier preserved the appendages and sent them and his notes to
Hunter's successor,
Philip Gidley King, who forwarded them to
Joseph Banks. Similar to Price, Barrallier's notes were not published until 1897.
[108] Reports of the first capture of a live "koolah" appeared in
The Sydney Gazette in August 1803.
[109] Within a few weeks Flinders' astronomer,
James Inman, purchased a specimen pair for live shipment to
Joseph Banks in England. They were described as 'somewhat larger than the Waumbut (
Wombat)'. These encounters helped provide the impetus for King to commission the artist
John Lewin to paint watercolours of the animal. Lewin painted three pictures, one of which was subsequently made into a
print that was reproduced in
Georges Cuvier's
The Animal Kingdom (first published in 1827) and several European works on natural history.
[110]
Botanist
Robert Brown
was the first to write a detailed scientific description of the koala
in 1814, based on a female specimen captured near what is now
Mount Kembla in the
Illawarra region of New South Wales. Austrian botanical illustrator
Ferdinand Bauer
drew the animal's skull, throat, feet, and paws. Brown's work remained
unpublished and largely unnoticed, however, as his field books and notes
remained in his possession until his death, when they were bequeathed
to the
British Museum (Natural History) in London. They were not identified until 1994, while Bauer's koala watercolours were not published until 1989.
[111] British surgeon
Everard Home included details of the koala based on eyewitness accounts of
William Paterson, who had befriended Brown and Bauer during their stay in New South Wales.
[112] Home, who in 1808 published his report in the journal
Philosophical Transactions of the Royal Society,
[113] gave the animal the scientific name
Didelphis coola.
[114]
The first published image of the koala appeared in
George Perry's (1810) natural history work
Arcana.
[115]
Perry called it the "New Holland Sloth" on account of its perceived
similarities to the Central and South American tree-living mammals of
genus
Bradypus.
His disdain for the koala, evident in his description of the animal,
was typical of the prevailing early 19th-century British attitude about
the primitiveness and oddity of Australian fauna:
[116]
"... the
eye is placed like that of the Sloth, very close to the mouth and nose,
which gives it a clumsy awkward appearance, and void of elegance in the
combination ... they have little either in their character or
appearance to interest the Naturalist or Philosopher. As Nature however
provides nothing in vain, we may suppose that even these torpid,
senseless creatures are wisely intended to fill up one of the great
links of the chain of animated nature ...".[117]
Natural history illustrator John Gould popularised the koala with his 1863 work The Mammals of Australia.
Naturalist and popular artist
John Gould illustrated and described the koala in his three-volume work
The Mammals of Australia
(1845–63) and introduced the species, as well as other members of
Australia's little-known faunal community, to the general British
public.
[118] Comparative anatomist
Richard Owen,
in a series of publications on the physiology and anatomy of Australian
mammals, presented a paper on the anatomy of the koala to the
Zoological Society of London.
[119]
In this widely cited publication, he provided the first careful
description of its internal anatomy, and noted its general structural
similarity to the wombat.
[120] English naturalist
George Robert Waterhouse,
curator of the Zoological Society of London, was the first to correctly
classify the koala as a marsupial in the 1840s. He identified
similarities between it and its fossil relatives
Diprotodon and
Nototherium, which had been discovered just a few years before.
[121] Similarly,
Gerard Krefft, curator of the
Australian Museum in Sydney, noted
evolutionary mechanisms at work when comparing the koala to its ancestral relatives in his 1871
The Mammals of Australia.
[122]
The first living koala in Britain arrived in 1881, purchased by
the Zoological Society of London. As related by prosecutor to the
society,
William Alexander Forbes, the animal suffered an accidental demise when the heavy lid of a
washstand
fell on it and it was unable to free itself. Forbes used the
opportunity to dissect the fresh female specimen, thus was able to
provide explicit anatomical details on the female reproductive system,
the brain, and the liver—parts not previously described by Owen, who had
access only to preserved specimens.
[123] Scottish
embryologist William Caldwell—well known in scientific circles for determining the reproductive mechanism of the
platypus—described the uterine development of the koala in 1884,
[124] and used the new information to convincingly place the koala and the
monotremes into an evolutionary time frame.
[125]
Prince Henry, Duke of Gloucester, visited the
Koala Park Sanctuary in
Sydney in 1934
[126] and was "intensely interested in the bears". His photograph, with
Noel Burnet, the founder of the park, and a koala, appeared in
The Sydney Morning Herald. After
World War II, when
tourism to Australia
increased and the animals were exported to zoos overseas, the koala's
international popularity rose. Several political leaders and members of
royal families had their pictures taken with koalas, including
Queen Elizabeth II,
Prince Harry,
Crown Prince Naruhito,
Crown Princess Masako,
Pope John Paul II, US President
Bill Clinton, Soviet premier
Mikhail Gorbachev, South African President
Nelson Mandela,
[127] Prime Minister
Tony Abbott, and Russian President
Vladimir Putin.
[128]
Cultural significance
Koala souvenir soft toys are popular with tourists
Amy and Oliver the bronze koalas (by Glenys Lindsay)
The koala is well known worldwide and is a major draw for Australian
zoos and wildlife parks. It has been featured in advertisements, games,
cartoons, and as soft toys.
[129]
It benefited the national tourism industry by over an estimated billion
Australian dollars in 1998, a figure that has since grown.
[130]
In 1997, half of visitors to Australia, especially those from Korea,
Japan, and Taiwan, sought out zoos and wildlife parks; about 75% of
European and Japanese tourists placed the koala at the top of their list
of animals to see.
[131]
According to biologist Stephen Jackson: "If you were to take a straw
poll of the animal most closely associated with Australia, it's a fair
bet that the koala would come out marginally in front of the kangaroo".
[129] Factors that contribute to the koala's enduring popularity include its childlike body proportions and
teddy bear-like face.
[132]
The koala is featured in the
Dreamtime stories and
mythology of indigenous Australians. The
Tharawal people believed that the animal helped row the boat that brought them to the continent.
[133]
Another myth tells of how a tribe killed a koala and used its long
intestines to create a bridge for people from other parts of the world.
This narrative highlights the koala's status as a
game animal and the length of its intestines.
[134]
Several stories tell of how the koala lost its tail. In one, a kangaroo
cuts it off to punish the koala for being lazy and greedy.
[135] Tribes in both Queensland and Victoria regarded the koala as a wise animal and sought its advice.
Bidjara-speaking people credited the koala for turning barren lands into lush forests.
[136] The animal is also depicted in
rock carvings, though not as much as some other species.
[137]
Early European settlers in Australia considered the koala to be a prowling
sloth-like animal with a "fierce and menacing look".
[138]
At the beginning of the 20th century, the koala's reputation took a
more positive turn, largely due to its growing popularity and depiction
in several widely circulated children's stories.
[139] It is featured in
Ethel Pedley's 1899 book
Dot and the Kangaroo, in which it is portrayed as the "funny native bear".
[138] Artist
Norman Lindsay depicted a more
anthropomorphic koala in
The Bulletin cartoons, starting in 1904. This character also appeared as Bunyip Bluegum in Lindsay's 1918 book
The Magic Pudding.
[140] Perhaps the most famous fictional koala is
Blinky Bill. Created by
Dorothy Wall
in 1933, the character appeared in several books and has been the
subject of films, TV series, merchandise, and a 1986 environmental song
by
John Williamson.
[141] The first
Australian stamp featuring a koala was issued by the Commonwealth in 1930.
[142] A television ad campaign for Australia's national airline
Qantas, starting in 1967 and running for several decades, featured a live koala (voiced by
Howard Morris), who complained that too many tourists were coming to Australia and concluded "I hate Qantas".
[143] The series has been ranked among the greatest commercials of all time.
[144]
The song "Ode to a Koala Bear" appears on the
B-side of the 1983
Paul McCartney/
Michael Jackson duet single
Say Say Say.
[141] A koala is the main character in
Hanna-Barbera's
The Kwicky Koala Show and
Nippon Animation's
Noozles, both of which were animated cartoons of the early 1980s. Food products shaped like the koala include the
Caramello Koala chocolate bar and the bite-sized cookie snack
Koala's March.
Dadswells Bridge in Victoria features a tourist complex shaped like a giant koala,
[127] and the
Queensland Reds rugby team has a koala as its mascot.
[145] The
Platinum Koala coin features the animal on the reverse and Elizabeth II on the
obverse.
[146]
The
drop bear is an imaginary creature in contemporary
Australian folklore featuring a predatory, carnivorous version of the koala. This hoax animal is commonly spoken about in
tall tales designed to scare
tourists. While koalas are typically docile herbivores, drop bears are described as unusually large and vicious
marsupials
that inhabit treetops and attack unsuspecting people (or other prey)
that walk beneath them by dropping onto their heads from above.
[147][148][149]
Conservation issues
While the koala was previously classified as
Least Concern on the
Red List, it was uplisted to
Vulnerable in 2016.
[1] Australian policy makers declined a 2009 proposal to include the koala in the
Environment Protection and Biodiversity Conservation Act 1999.
[19] In 2012, the Australian government listed koala populations in Queensland and New South Wales as
Vulnerable,
because of a 40% population decline in the former and a 33% decline in
the latter. Populations in Victoria and South Australia appear to be
abundant; however, the
Australian Koala Foundation
argues that the exclusion of Victorian populations from protective
measures is based on a misconception that the total koala population is
200,000, whereas they believe it is probably less than 100,000.
[150]
Koala skins were widely traded early in the 20th century.
Koalas were hunted for food by Aboriginals. A common technique used
to capture the animals was to attach a loop of ropey bark to the end of a
long, thin pole, so as to form a
noose.
This would be used to snare an animal high in a tree, beyond the reach
of a climbing hunter; an animal brought down this way would then be
killed with a stone hand axe or hunting stick (
waddy).
[151] According to the customs of some tribes, it was considered
taboo to skin the animal, while other tribes thought the animal's head had a special status, and saved them for burial.
[152]
The koala was heavily hunted by European settlers in the early 20th century,
[153]
largely for its thick, soft fur. More than two million pelts are
estimated to have left Australia by 1924. Pelts were in demand for use
in rugs, coat linings,
muffs, and as trimming on women's garments.
[154] Extensive
cullings
occurred in Queensland in 1915, 1917, and again in 1919, when over one
million koalas were killed with guns, poisons, and nooses. The public
outcry over these cullings was probably the first wide-scale
environmental issue that rallied Australians. Novelist and social critic
Vance Palmer, writing in a letter to
The Courier-Mail, expressed the popular sentiment:
"The
shooting of our harmless and lovable native bear is nothing less than
barbarous ... No one has ever accused him of spoiling the farmer's
wheat, eating the squatter's grass, or even the spreading of the prickly
pear. There is no social vice that can be put down to his account ...
He affords no sport to the gun-man ... And he has been almost blotted
out already from some areas."[155]
Despite the growing movement to protect native species, the poverty
brought about by the drought of 1926–28 led to the killing of another
600,000 koalas during a one-month
open season in August 1927.
[156]
In 1934, Frederick Lewis, the Chief Inspector of Game in Victoria, said
that the once-abundant animal had been brought to near extinction in
that state, suggesting that only 500–1000 remained.
[157][158]
Scent gland on the chest of an adult male - Lone Pine Koala Sanctuary
The first successful efforts at conserving the species were initiated by the establishment of Brisbane's
Lone Pine Koala Sanctuary
and Sydney's Koala Park Sanctuary in the 1920s and 1930s. The owner of
the latter park, Noel Burnet, became the first to successfully breed
koalas and earned a reputation as the foremost contemporary authority on
the marsupial.
[159] In 1934,
David Fleay, curator of Australian mammals at the
Melbourne Zoo,
established the first Australian faunal enclosure at an Australian zoo,
and featured the koala. This arrangement allowed him to undertake a
detailed study of its diet in captivity. Fleay later continued his
conservation efforts at
Healesville Sanctuary and the
David Fleay Wildlife Park.
[160]
Since 1870, koalas have been introduced to several coastal and
offshore islands, including Kangaroo Island and French Island. Their
numbers have significantly increased,
[161] and since the islands are not large enough to sustain such high koala numbers,
overbrowsing has become a problem.
[162]
In the 1920s, Lewis initiated a program of large-scale relocation and
rehabilitation programs to transfer koalas whose habitat had become
fragmented or reduced to new regions, with the intent of eventually
returning them to their former range. For example, in 1930–31, 165
koalas were
translocated to
Quail Island.
After a period of population growth, and subsequent overbrowsing of gum
trees on the island, about 1,300 animals were released into mainland
areas in 1944. The practice of translocating koalas became commonplace;
Victorian State manager Peter Menkorst estimated that from 1923 to
2006, about 25,000 animals were translocated to more than 250 release
sites across Victoria.
[163]
Since the 1990s, government agencies have tried to control their
numbers by culling, but public and international outcry has forced the
use of translocation and
sterilisation, instead.
[164]
Road sign depicting a koala and a kangaroo
One of the biggest
anthropogenic threats to the koala is
habitat destruction and
fragmentation. In coastal areas, the main cause of this is
urbanisation,
while in rural areas, habitat is cleared for agriculture. Native forest
trees are also taken down to be made into wood products.
[165] In 2000, Australia ranked fifth in the world by deforestation rates, having cleared 564,800 hectares (1,396,000 acres).
[166]
The distribution of the koala has shrunk by more than 50% since
European arrival, largely due to fragmentation of habitat in Queensland.
[49]
The koala's "vulnerable" status in Queensland and New South Wales means
that developers in these states must consider the impacts on this
species when making building applications.
[150] In addition, koalas live in many
protected areas.
[1]
While urbanisation can pose a threat to koala populations, the
animals can survive in urban areas provided enough trees are present.
[167] Urban populations have distinct vulnerabilities:
collisions with vehicles and attacks by domestic dogs kill about 4,000 animals every year.
[105] Injured koalas are often taken to wildlife hospitals and
rehabilitation centres.
[167] In a 30-year
retrospective study performed at a New South Wales koala rehabilitation centre,
trauma
(usually resulting from a motor vehicle accident or dog attack) was
found to be the most frequent cause of admission, followed by symptoms
of
Chlamydia infection.
[168]
Wildlife caretakers are issued special permits, but must release the
animals back into the wild when they are either well enough or, in the
case of joeys, old enough. As with most native animals, the koala cannot
legally be kept as a pet in Australia or anywhere else.
[169]
Koala range (red – native, purple – introduced)
.jpg)
