Koalas - Uniquely Australian
The Koala is an ambassador and much-loved symbol of Australia. A favourite tourist attraction, the unique and endearing Koala is well known internationally and provides a positive, warm image abroad for Australia. Photographs and video images flashed around the world showing Heads of State and famous celebrities cuddling Koalas put Australia and its unique attractions in the spotlight.
The Koala's high profile worldwide has led naturalists to recognise that this animal ambassador can be used with great impact for the cause of conservation. It is so distinctively different from other species that it is regarded as an evolutionary orphan - the sole surviving branch of a family tree - it is known to be a member of a group with a fragmentary fossil history of at least 15 million years.
| Despite considerable differences in habits and physical make-up, the Koala' closest relative is the Wombat. They have so many features of basic anatomy in common that it seems clear that they shared a common ancestor, probably about 25 million years ago. The virtual absence of a tail is certainly not, in itself, evidence of a relationship but the lack of this structure in the Koala (the only arboreal marsupial which lacks it) is puzzling. It has been suggested that the tail is reduced because the common ancestor was a slow-moving terrestrial animal which had little use for one but there is no other feature in the anatomy of the Koala to suggest that its ancestors were ever other than arboreal.|
The koala lives high in the branches of eucalyptus trees in eastern Australia.
Eucalypt leaves have a high fibre and a low protein content. They contain strong-smelling oils, phenolic compounds and sometimes cyanide compounds which make them unpalatable or even poisonous to most mammals. To cope with this diet, the Koala has numerous adaptations, cheek pouches for storing food and, most significantly an enlarged caecum (digestive system), proportionally longer than in any other mammal, in which microbial fermentation takes place. Oils and phenolic compounds are detoxified in the liver and leaves containing cyanide compounds are probably avoided. There are no grounds for the widespread belief that eucalyptus oils intoxicate Koalas, rendering them lethargic.
|Over its range from the tropics to the cool-temperate regions, the Koala is limited to areas where there are acceptable food trees. It feeds predominantly on the foliage of eucalypts, notably River Red Gum and Forest Red Gum in the north, and Grey Gum, Manna Gum, swamp Gum and Blue Gum in the southeast. Many other eucalypts and some non-eucalypts may contribute to the diet and there are marked local and seasonal preferences. As eucalypt leaves have a high water content, the Koala normally does not drink but obtains sufficient water from its food - 500g to 1kg of leaves daily.|
A shy creature, with nocturnal habits, the Koala sleeps in a fork of a tree during the greater part of the day, spending approximately 19 hours a day resting and sleeping. It moves about and feeds at night with a peak of activity just after sunset. It is an accomplished climber, ascending the trunk of the tree by clasping it with the sharp claws of its hands and then bringing the hindfeet up together in a bounding movement. When walking on a branch it grips with the first toe of the hindfoot and with the first two digits of the hand opposed to the other three. The Koala may also travel for some distance on the ground where it either bounds along, using the hindlegs in much the same way as it climbs, or walks quadrupedally.
|The Koala is solitary and members of a population are usually evenly distributed in a changing pattern through the available forest. Males are larger than females, reaching a height of up to 80cm and a weight of up to 13.5 kg (females 7.9 kg). The male has a large sternal gland which he uses in the breeding season for scent marking, grasping a tree trunk and rubbing his chest up and down against it. This behaviour and the loud, harsh bellowing of the male seem to be involved in the spatial separation of mature males and in their competition for mates.|
Apart from size, males can be readily distinguished from females by their flat head, smaller ears and larger nose. The female's more rounded head and more tufted ears can be clearly distinguished in profile.
At the age of 12 months it is fully weaned and independent of its mother and by 18 months it has usually dispersed away from the area where it was born. Mortality may be high during this dispersal phase. Females become sexually mature at the age of 2 years, males at 3-4 years. There is little information on longevity in the wild but captive animals have lived to over 15 years. A koala population is not self-regulating and, in the absence of such predators as Aborigines and the Dingo, may outstrip the food resources of an area, defoliate and kill the food trees and become locally extinct.
|Breeding occurs in summer and most mature females produce one young (rarely twins) each year. It weighs less than 0.5 g at birth and remains in the female's rear-facing pouch for 7 months, suckling on one of the 2 nipples.|
Weaning commences in the last months of pouch life and the infant's change to a diet of leaves is initiated by its feeding on a soft faeces, apparently from the caecum of the mother. This is thought to inoculate the young animal with the micro-organisms required for its own digestive system to function. After leaving the pouch, a young Koala feeds on a mixed diet of milk and leaves, grows rapidly and travels clinging to its mother's back.
Although shooting and deforestation have reduced the distribution of the Koala, particularly in Queensland, its range has been extended following liberation of animals into areas where the species was not known to exist at the time of European occupation
of Australia. However, continued clearing of large tracts of eucalypt forest and the consequent restriction of populations to small patches of discontinuous and possibly suboptimal habitat, leave the long term future of the species in some doubt. It seems
clear that the survival of many populations will depend upon appropriate management.
Aboriginal legend first records the koalas existence, telling of the pact the Kulin people made with the koalas, by which they promised to treat the animals with respect if they would stop taking the Kulin's water and give them good advice when asked. Dreamtime myth also ascribes to koalas the ability to disappear at will. Indeed, it was 10 years before the early European settlers first sighted a koala, and a further three before one was captured.
Koalas - Once Hunted in Their Thousands
The habitat available to them had been reduced by forest clearing but it seems that, in what remained, their density increased to the point where it became economic, towards the end of the nineteenth century, to establish a trade based on their skins. There can be little doubt that unregulated harvesting resulted in an overkill, the absence of the species from some areas which now appear to be appropriate habitats may be the result of local extinctions.
|There is considerable evidence that, prior to European settlement, and particularly in areas of dry sclerophyll and woodland, koalas were under great predatory pressure from Aborigines (who took them in the trees) and dingoes (which took them on the
ground). As Europeans took over the land for agriculture and grazing, those Aborigines who were not killed or displaced had their diet largely changed towards the European pattern. Much effort was directed to reducing the numbers of dingoes and, with the
reduction of these two predators, koala populations began to increase.|
Koalas were hunted in Australia for their pelts well into the nineteen thirties. However, the widespread public revulsion against the killing of a harmless animal led to a policy of total protection which poses long-term problems. In the absence of any predation or culling, koala populations are limited by available food, by disease, or by reduction of fecundity due to a preponderance of aged animals - all or any of which factors may lead to crises resulting in population crashes.
In the nineteen seventies as a result of a poorly completed count of koalas in the wild, some naturalists believed the koala may be endangered. International attention was suddenly focused on Australia and a flurry of scientific studies of the koala were the immediate result.
Within a decade, conservationists were content that the future of the koala on a national scale was secure, but worried that some populations may be threatened with the encroachment of towns and cities, farms, roads and mining activities on their natural habitat.
The Name 'Koala'
After the Koala was first brought to the notice of international naturalists just over 200 years ago, it was more by good luck than anything else that it was given its distinctly Australian name.
As colonial influence radiated out from Sydney Cove, meeting different Aboriginal groups, many names were denoted for the frizzle-grey tree-dweller which was both revered by the local tribes and used as a food resource. The names written down, quite possibly, were inaccurate, because of the problems of transliteration from spoken dialect to English. These include:
Cullawine, Karbor, Colo, Koolah, Colah, Koolewong, Boorabee, Burroor,
Bangaroo, Banjorah, Burrenbong, Pucawan and Goribun.
|Somehow the name koala seems to suit this endearing creature but it could easily have ended up as cullawine, coolewong, or even bangaroo. Or, it might have been given an English name.|
Over a relatively long period it was called a sloth, a monkey and a monkey-bear before Australians settled for koala. While many writers over the years have claimed the name koala was an Aboriginal word, it is most likely an anglicised version of one of many Aboriginal tribal names. The most common version of the story is that it derived from an Aboriginal word meaning 'no drink' because, generally, the koala does not need to drink, obtaining its moisture requirements from the hundreds of gum leaves it consumes every day. However, no annotation exists about the actual derivation.
Earliest European Sighting
In October, 1803, the Sydney Gazette newspaper used the name koolah in a wonderful description of the first live specimen brought into the settlement. It is easy to imagine how Price's phonetic spelling
'cullawine', Barralier's 'colo' and the Gazette's 'coolah' could evolve to koala.
|The earliest sighting by a European was on January 26, 1789. The New South Wales colonial governor at this time, John Hunter, was a keen student of natural history and encouraged his staff and colonial officials to record interesting finds. After an expedition to the Blue Mountains, John Price, one of Hunter's free-servants reported:
"There is another animal which the natives call a cullawine, which much resembles the sloths in America".
Four years later Ensign F Barrallier wrote:
"[The Aborigines] brought portions of a monkey (in the Native language colo) , but they had cut it in pieces ... I could only get two feet ... I sent these two feet to the Governor, preserved in a bottle of brandy".
This was the name used in 1808 in the first scientific report about the animal, by Everard Home, published in "Philosophical Transactions' of the Royal Society in London. Home was also the first naturalist to liken the koala (incorrectly) to the bear, but then, his description was obtained second-hand, from Lieutenant-Colonel William Paterson, a Lieutenant Governor of New South Wales. Other observation did not mention that the koala had a pouch. The koala was subsequently often referred to as Australia's native bear.
Intriguing Discoveries of the Animal World
In 1811, English naturalist George Perry's book, Arcana, (an illustrated guide to the most intriguing discoveries of the animal world) dubbed it the 'Koala' or 'New Holland Sloth' and was none too complimentary in his description. He labelled the 'Koala' awkward,
unweildy, uncouth and noted he was
"at a loss to imagine for what scale of usefulness or happiness such an animal could by the Great Author of Nature be destined ... 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 ..."
Little could Perry foresee the huge amount of scientific curiosity his unflattering comments would arouse and the resulting international publicity for both Australia and the koala. It is ironic that an animal which received such 'bad press' to begin with should become one of Australia's best loved international promotional ambassadors.
In 1816, the koala was given the scientific name phascolarctos from the Greek for 'leather pouch' and 'bear', later gaining the qualification cinerus meaning ash-coloured.
'Complete Book of Australian Mammals' - Australian Museum, 1983
'The Tenth Proof Issue of The Australian Koala Platinum Coins' - booklet issued by the Perth Mint - 1997;
Publicity brochure for the 1990 Proof Issue of the Australian Koala, Perth Mint.
'IMP Wildlife Fact File', Card 32 Group 1, 1999.
The Koala appears on the following Australian coins:
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Last modified: 05 December, 2007