The KOALA Phascolarctos cinerus

Koalas - Uniquely Australian

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.

Habitats

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.

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.

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.

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

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'

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

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

"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 ..."

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.

Sources:
'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.

• Australian $200 Gold - 1980, 1983, 1984, 1985 & 1986.
• Australian Bullion Platinum Coins
• Bullion Silver 1oz Koala Medallions since 1997.