Australian Wildlife: Koala





Koala (Phascolarctos cinereus)

Of all the animals that are unique to Australia, the koala and the kangaroo are at the top of the list of "must see" animals among overseas visitors. Cullewine, koolewong, colo, colah, koolah, and koala appear as the Aboriginal names for the koala in the various dialects of eastern New South Wales, although these recorded names are undoubtedly complicated by problems of transliteration and printers  errors. The word is erroneously said to mean "doesn't drink".

In 1808 Lieutenant-Governor Colonel William Paterson wrote that the native name was koala wombat , which later became koala. The scientific name of the koala's genus, Phascolarctos, is derived from Greek phaskolos "pouch" and arktos "bear". This gave rise to the misleading name of native bear  and the midconception that the koala is a bear. This attractive and unique animal is in fact a marsupial, or pouch-carrying mammal, like another famous Australian, the kangaroo.

In The Wild

The koala can be found throughout the coastal regions of eastern and southern Australia, from near Adelaide to the southern part of Cape York Peninsula. However, as they are nocturnal and live in the high branches of tall trees, they are very difficult to spot by the untrained eye of passers by. Kangaroo Island, SA, and Phillip Island, Vic., are two places in Australia where one can almost be guaranteed of seeing koalas in their natural environment. Here, like a few other lesser known or less accessible places along the eastern seaboard, koala colonies thrive in controlled conditions where predators and competition is absent. These sanctuaries were established to ensure the survival of the species. Koalas can be seen in the tree above at dedicated koala sanctuaries, as well as at close range in public access enclosures.

Gunnedah, on the south-west slopes of New South Wales, is home to one of the largest and healthiest colonies of koalas in Australia.



In Captivity

Most Australian zoos, wildlife parks and sanctuaries have koalas on display in enclosures. Many have viewing platforms to allow close range viewing and some have opportunities for visitors to be photographed holding koalas.

Geographic Range

Koalas live in eastern Australia and range from northern Queensland to southwestern Victoria. Populations also extend for considerable distances inland in regions with enough moisture to support suitable woodlands. The koalas of South Australia were largely exterminated during the early part of the 20th century, but the state has since been re-populated with Victorian stock. The koala is not found in Tasmania or Western Australia, though they have been introduced to Western Australia and nearby islands.

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).



Description

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.

Koalas have dense, woolly 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 shorter 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

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.



Behaviour

Koalas are polygynous and relatively sedentary. Because of their low quality diet, koalas conserve energy by their behaviour. 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 sub-adult 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 individuals presence and warn off other males. The only vocalization generally heard from females and sub-adult males is a harsh wailing distress call given when harassed by adult males. Copulation is brief generally 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 behaviour. 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.

Food Habits

Koalas are herbivorous feeding on both eucalypt and non-eucalypt species. However the bulk of their diet comes from only a few eucalypt species. Koalas have a highly specialized diet in which they eat only 20 of the 350 species of eucalyptus and prefer only 5 species. They feed at night. An adult koala can eat 500g daily.

Conservation Status

The koala holds no special status although it is generally considered at the lower risk end of near threatened species. 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.

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