Each koala's ‘home' is made up of several trees called home trees, and they visit these same trees regularly. Each koala has its own home range, which overlaps those of other koalas but except for breeding purposes, they do not visit another koala's home trees. The size of each home range depends upon a range of factors including the quality of the habitat and the sex, age and social position in the population of the koala.
Koalas do not live in rainforests or desert areas. They live in the tall eucalypt forests and low eucalypt woodlands of mainland eastern Australia and on some islands off the southern and eastern coasts. Queensland, NSW, Victoria and South Australia are the only states where koalas are found naturally in the wild.
KOALA FACTS
- Koalas are not bears. They are MARSUPIALS, which means that their young are born immature & they develop further in the safety of a pouch.
- Koalas have 5 digits on each front paw, two of which are opposed to the others, much like our thumbs are able to be moved differently from the fingers. This helps them to hold firmly onto the branches and to grip their food. The 2nd and 3rd digits on their hind paws are fused together to form a grooming claw.
- Koalas are mostly nocturnal. Nocturnal animals are awake at night and asleep during the day. Koalas, however, sleep for part of the night and also sometimes move about in the daytime. They often sleep for up to 18 hours each day.
- There is a myth that koalas sleep a lot because they ‘get drunk' on gum leaves. Fortunately, this is not correct! Most of their time is spent sleeping because it requires a lot of energy to digest their toxic, fibrous, low-nutrition diet and sleeping is the best way to conserve energy.
- Koalas in the southern parts of Australia are considerably larger and have thicker fur than those in the north. This is thought to be an adaptation to keep them warm in the colder southern winters.
- A mature male has a dark scent gland in the centre of his white chest, which exudes a dark sticky substance. He rubs this on his trees to indicate to other koalas that this is his territor
- Koalas also communicate with each other by making a range of noises. The most startling and unexpected of these in such a seemingly gentle animal is a sound like a loud snore and then a belch, known as a ‘bellow'.
KOALA DIET
- There are well over 600 varieties of eucalypts. Koalas eat only some of these. They are very fussy eaters and have strong preferences for different types of gum leaves. Within a particular area, as few as one, and generally no more than two or three species of eucalypt will be regularly browsed (we call these "primary browse trees") 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.
- A forest can only have a certain number of koalas living in it. This is called the forest's ‘carrying capacity'. Like pasture for sheep, the available gum leaves can only feed a certain number of koalas.
- An adult koala eats about a half a kilogram to one kilogram of leaves each night, depending on many factors, including the size and sex of the koala and where the koala lives.
- Koalas have an unusual fibre-digesting organ called a caecum. Other animals, such as humans also have a caecum, but the koala's is very long (200 cms) and it has a blind end. It contains millions of bacteria which break down the fibre into substances which are easier to absorb. Even so, the koala is still only able to absorb 25 per cent of fibre eaten, hence their need to eat large amounts of leaves.
- Koalas don't normally need to drink as they get all the moisture they need from the gumleaves. However, they can drink if necessary, such as in times of drought when the leaves may not contain sufficient moisture.
KOALA LIFE CYCLE
- Younger breeding females usually give birth to one joey each year, depending on a range of factors. However, not all females in a wild population will breed each year. Some, especially older females, will produce offspring only every two or three years.
- Koala young are known as ‘joeys'; scientists often refer to them using terms like ‘juveniles', ‘pouch young', and ‘back young'.
- When the joey is born, it's only about 2 centimetres long, is blind and furless and its ears are not yet developed. On its amazing journey to the pouch, it relies on its well-developed senses of smell and touch, its strong forelimbs and claws, and an inborn sense of direction. In the pouch, it attaches itself to one of the two teats which swells in its mouth, preventing it from being dislodged from its source of food.
- The joey stays in its mother's pouch for about 6 or 7 months, drinking only milk.
- Before it can tolerate gumleaves which are toxic for most mammals, the joey must feed on a substance called ‘pap', which is a specialised form of the mother's droppings that is soft and runny. This allows the mother to pass on to the joey special micro-organisms from her intestine which are necessary for it to be able to digest the gum leaves. It feeds on this for a period of up to a few weeks, just prior to it coming out of the pouch at about 6 or 7 months of age.
- After venturing out of the pouch, the joey rides on its mother's abdomen or back, although it continues to return to her pouch for milk until it is too big to fit inside.
- The joey leaves its mother's home range between 1 and 3 years old, depending on when the mother has another joey.
- Koalas are fully grown by their third or fourth year. By this time they need to have found their own home range, either in a home range left vacant by a dead koala or in a new area of the forest. This is one reason why koalas need quite large areas of habitat.
KOALA THREATS
- Chlamydia is an organism which lives in the body tissues of most healthy koalas. In normal populations, we believe that Chlamydia may act as an inbuilt control mechanism to limit the population so that the trees are not over browsed, ensuring that only the strongest and fittest animals survive to breed.
- Chlamydia can also sometimes make the koalas sick, but usually only when they get stressed, such as when their habitat is destroyed and, as a result, they have to cope with the dangers of cars, dogs and lack of food.
- Habitat loss is the greatest problem facing koalas. The main reasons for this are land clearing, bush fires and diseases of the eucalypts, like ‘dieback', which causes the trees to die.
- The AKF estimates that around 4,000 koalas are killed each year by dogs and cars alone as a result of the loss of their habitat,
- Australia has one of the highest land clearing rates in the world. Eighty percent of original koala habitat has already disappeared.
- Although koalas themselves are protected by law, around eighty percent of any remaining habitat occurs on privately owned land and almost none of that is protected by legislation.
- The AKF believes that the Federal Government should be responsible for the protection of koala habitat on private land and not leave it up to the present piece-meal approach of each state being responsible.
- That is why the AKF is planning to write a National Koala Act and have it passed in Federal Parliament.
- The AKF estimates that there are likely to be less than 100,000 koalas remaining in Australia today. Most of their habitat has already been lost. This makes it vitally important to save what is left.
Source : http://www.wildlifeextra.com/go/world/koala.html#cr
Tidak ada komentar:
Posting Komentar