The koala is a small bear-like, tree-dwelling, herbivorous marsupial which averages about 9kg (20lb) in weight. Its fur is thick and usually ash grey with a tinge of brown in places.
The koala gets its name from an ancient Aboriginal word meaning "no drink" because it receives over 90% of its hydration from the Eucalyptus leaves (also known as gum leaves) it eats, and only drinks when ill or times when there is not enough moisture in the leaves. ie during droughts etc.
The koala is the only mammal, other than the Greater Glider and Ringtail Possum, which can survive on a diet of eucalyptus leaves.
'Habitat' refers to the types of bushland that koalas like to live in. They are found in a range of habitats, from coastal islands and tall eucalypt forests to low woodlands inland.
Koalas today are found in Queensland , New South Wales , Victoria and South Australia .
Research has shown that socially stable koala populations occur only when there are favourite tree species present. Even if a selection of tree species known to be used by koalas occurs within an area, the koala population will not use it unless one or two favourite species are available.
In Australia there are over 600 types of eucalypts, but koalas will only eat 40-50 varieties with only about 10 being preferred. Within a particular area, as few as one, and generally no more than two or three species of eucalypt will be regularly browsed while a variety of other species, including some non-eucalypts, appear to be browsed occasionally or used for just sitting or sleeping in.
Different species of eucalypts grow in different parts of Australia, so a koala in Victoria would have a very different diet from one in Queensland. Koalas like a change, too, and sometimes they will eat from other trees such as wattle or tea tree.
Eucalyptus leaves are very fibrous and low in nutrition, and to most animals are extremely poisonous. To cope with such a diet, nature has equipped koalas with specialised adaptations. A very slow metabolic rate allows koalas to retain food within their digestive system for a relatively long period of time, maximising the amount of energy able to be extracted. At the same time, this slow metabolic rate minimises energy requirements and they will sleep for up to 18 hours per day in order to conserve energy.
Each koala eats approximately 200 to 500 grams of leaves per day. The teeth are adapted to deal with for this. The sharp front incisors nip the leaves from the branches and the molars(back teeth) are shaped to allow the koala to cut and shear the leaves rather than just crush them. A gap between the incisors and the molars, called a 'diastema', allows the tongue to move the mass of leaves around the mouth efficiently.
The Koala is well suited to life in the trees. The koala has an excellent sense of balance and its body is lean and muscular and its quite long, strong limbs support its weight when climbing. The arms and legs are nearly equal in length and the koala's climbing strength comes from the thigh muscle joining the shin much lower than in other animals.
Its paws are especially adapted for gripping and climbing with rough pads on the palms and soles helping it to grip tree trunks and branches. Both front and hind paws have long sharp claws and each paw has five digits. On the front paw, two fingers are opposed to the other three, rather like a human's thumb, so they are able to be moved in opposition to the fingers. This allows the koala to grip more securely. On the hind paw, there is no claw on the big toe, and the second and third toes are fused together to form a 'grooming claw'.
Koalas have a thick woolly fur which protects them from both high and low temperatures.It also acts like a 'raincoat' to repel moisture when it rains. The fur varies in colour from light grey to brown, with patches of white on the chest and neck, inside arms and legs and inside the ears. Mature males are recognisable by the brown 'scent gland' in the centre of their white chest.
The fur on the koala's bottom is densely packed to provide a 'cushion' for the hard branches it sits on, and has a 'speckled' appearance which makes koalas hard to spot from the ground.
An adult male koala can weigh between 8 and 14 kilograms and a female between 6 and 11 kilograms, with the heavier animals coming from the southern areas where they have adapted to the colder climate by an increase in body weight and thicker fur. If you see Koalas in Queensland, they look noticably smaller than Koalas from Victoria.
Koalas are mostly nocturnal animals and they are most active during the night and at dawn and dusk. This is because in the cooler hours they are less likely to lose precious moisture and energy than they would during the hotter daylight hours. An average of eighteen to twenty hours each day are spent resting and sleeping, and the remainder for feeding, moving around, grooming and social interaction.
The Koala's nose is one of its most important features, and it has a very highly developed sense of smell. This is necessary to differentiate between types of gum leaves and to detect whether the leaves are poisonous or not.
The Koala's digestive system is especially adapted to detoxify the poisonous chemicals in the leaves. The toxins are thought to be produced by the gum trees as a protection against leaf-eating animals like insects. Trees which grow on less fertile soils seem to have more toxins than those growing on good soils. This could be one reason why koalas will eat only certain types of eucalypts, and why they will sometimes even avoid them when they are growing on certain soils.
When approaching a tree to climb, koalas spring from the ground and catch their front claws in the bark, then bound upwards. Claw marks are usually visible on the trunks of trees regularly used as home trees by koalas.
In the safety of their home trees, koalas assume a wide variety of sitting and sleeping postures, and they will move around the tree during the day and night to catch the sun or the breezes. On hot days it is common to see them with limbs dangling in an effort to keep cool, and during colder times, curled up in a ball to conserve body heat.
When descending a tree, koalas come down bottom first. They regularly descend to the ground to change trees, and it is there that they are most vulnerable to predators such as dogs, foxes and dingoes, and also to the risk of injury or death from cars. They walk with an awkward-looking gait and can also run. Koalas have sometimes been observed swimming, but this is not a regular occurrence.
Since European settlement, approximately 80% of Australia's eucalypt forests have been decimated. Of the remaining 20% almost none is protected and most occurs on privately-owned land.
Settlers favoured the rich fertile lands along the eastern seaboard to have their farms and urban developments. Unfortunately, this is where the majority of koalas are already living because they also like to live in trees which are growing in fertile soils.
The main causes of loss of habitat include:
Clearing of the land for expansion of human settlement eg:-
agriculture, housing, mining, forestry,factories and roads.
The results of this would include:-
loss of habitat
increased disturbance by humans
injury or death from traffic
injury or death from dogs and cats
effects of garden pesticides getting into waterways
increased competition for food and territory because of overcrowding
increased stress on animals, making them more susceptible to disease.
It has also been documented that over 4000 koalas are killed each year by dogs and cars. It easy to see that the biggest threat to the Koala population is the human.
The Bare-nosed wombat was, until recently, generally refered to as the Common wombat. It is also known as the Coarse haired wombat, the Naked nosed wombat, the Forest wombat, the Island wombat, and the Tasmanian wombat. Its nickname is "The bulldozer of the bush"
All Bare-nosed or Common wombats are generally considered a single species, Vombatus ursinus; however, they are sometimes classified as separate species or subspecies depending on where they live.
The Australian mainland species is sometimes classified as a separate species, Vombatus hirsutus, but is more commonly classified as a subspecies, Vombatus ursinus hirsutus.
The Bare-nosed or Common wombats that live in Tasmania and on Flinders Island in Bass Strait are slightly smaller than the mainland wombats and are often considered two separate subspecies. The wombats from Flinders Island are the smallest and are called Vombatus ursinus ursinus. The Tasmania wombats are called Vombatus ursinus tasmaniensis.
The Bare-nosed or Common wombat is the most widespread. They were once found throughout southeast Australia, but their range is now restricted to the coastal regions of southeast Australia, including: the southeast tip of Queensland, the eastern region of New South Wales, the eastern half and southern areas of Victoria, and the southeastern tip of South Australia. Their population is much less than it used to be.
Bare-nosed wombats are widespread in Tasmania, especially in the Northeast. They also occur on Flinders Island, which is located between Australia and Tasmania. Bare-nosed wombats used to be native to all the islands of the Bass Strait (the waters between Australia and Tasmania), but now are restricted to Flinders Island.
are-nosed wombats are considered solitary except during the breeding season, but there have been reports that they visit each other's burrows on occasion. Some reports say that Bare-nosed wombats may also form colonies.
The Bare-nosed wombat is unprotected in Victoria. The Bare-nosed wombats on Flinders Island are classified as vulnerable.
The kangaroo is one of Australias most iconic animals, and most species are endemic to Australia. There are over 60 different species of kangaroo and their close relatives, with all kangaroos belonging to the super family Macropodoidea (or macropods, meaning great-footed). The super family is divided into the Macropodidae and the Potoroidae families.
The Macropodidae (macropod) family includes kangaroos, wallabies, wallaroos, pademelons, tree-kangaroos and forest wallabies. Species in the macropod family vary greatly in size and weight, ranging from 0.5 kilograms to 90 kilograms. The Potoroinae (potoroid) family of kangaroos includes the potoroo, bettong and rat-kangaroo, which live only in Australia.
Kangaroos of different types live in all areas of Australia, from cold-climate areas and desert plains, to tropical rainforests and beaches.
Kangaroos are herbivorous, eating a range of plants and, in some cases, fungi. Most are nocturnal but some are active in the early morning and late afternoon. Different kangaroo species live in a variety of habitats. Potoroids, for example, make nests while tree-kangaroos live above ground in trees. Larger species of kangaroo tend to shelter under trees or in caves and rock clefts.
Kangaroos of all sizes have one thing in common: powerful back legs with long feet. Most kangaroos live on the ground and are distinguished from other animals by the way they hop on their strong back legs. A kangaroos tail is used to balance while hopping and as a fifth limb when moving slowly.
All female kangaroos have front-opening pouches that contain four teats.
This is where the joey, or young kangaroo, is raised until it can survive outside the pouch.
Most kangaroos have no set breeding cycle and are able to breed all year round.
Because they are such prolific breeders, a kangaroo population can increase fourfold in five years if it has continuous access to plentiful food and water.