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KOALA - WHEN A BEAR'S NOT REALLY A BEAR AT ALL!

The koala is a small bear-like, tree-dwelling, herbivorous marsupial which carries it's young in a pouch.

We often hear these adorable Aussies called ‘koala bears’, but they are actually not bears at all. Koalas are marsupials, so they carry their young in a pouch, unlike bears which carry their young in the womb until they are well developed. The koala lives almost entirely on eucalypt leaves and they have a very low metabolic rate for a mammal, which is why they can sleep for up to 20 hours a day!

Koala eating gum leaves
Koala eating it's favourite diet of eucalyptus or gum leaves

Koalas vary in size and colour depending on where they live in Australia. Koalas found in the southern distributions (Southern NSW and Victoria) tend to be slightly larger and darker than those in the northern areas (Northern NSW and QLD). This is likely to be related to the different temperatures and is a feature exhibited by many species whose distribution encompasses large climatic variations.

The most notable physical aspect of the Koala would have to be its big fluffy ears. Koalas have a great sense of hearing and an even better sense of smell. This is how they select which leaves are the best to eat. Their eyesight is not too good, and therefore detection of predators is generally by sound. They possess very strong forearms and extremely long, sharp claws for climbing. They also  have two thumbs on their front paws to help them climb, to hold onto the tree and to grip their food.

The most notable physical aspect of the Koala would have to be its big fluffy ears

The word koala comes from the Dharug word 'gula' (gula being an ancient Aboriginal word meaning "no drink" because the koala receives over 90% of its hydration from the Eucalyptus - or 'gum' -  leaves).  Although the vowel 'u' was originally written in the English orthography as "oo" (in spellings such as coola or koolah), it was changed to "oa", possibly in error.

The koala is the only mammal, other than the Greater Glider and Ringtail Possum, which can survive on a diet of eucalyptus leaves.

Koalas lining up for a feed
Koalas lining up for a feed

Breeding

Females generally start breeding at about three or four years of age and usually produce only one offspring each year. However, not all females in a wild population will breed each year. Some produce offspring only every two or three years, depending on factors such as the age of the female and the quality of its habitat. In the average female's life span of about twelve years, this means that one female may produce only 5 or 6 offspring over her lifetime.

Once a female has conceived, it is only 34-36 days before the birth of the new baby, called a "joey". The tiny baby which is roughly 2 centimetres long and weighs less than 1 gram, looks rather like a pink jellybean as it is totally hairless, blind and has no ears.

Size of a koala joey at birth
Size comparison of a koala joey at birth and a 20 cent coin

The joey makes its way from the birth canal to the pouch completely unaided, relying on its already well-developed senses of smell and touch, strong forelimbs and claws and an amazing sense of direction. Once inside the safety of the pouch, it attaches itself to one of the two teats, which swells to fill its mouth. This prevents the joey from being dislodged from its source of food. The mother contracts her strong sphincter muscle at the pouch opening to prevent the baby from falling out.

The young koala drinks only mother's milk for the first six to seven months and remains in the pouch for that time, slowly growing and developing eyes, ears, fur etc. At about 22 weeks, its eyes open and it begins to peep out of the pouch. From about 22 to 30 weeks, it begins to feed upon a substance called "pap" which the mother produces in addition to milk. Pap is a specialised form of faeces, or droppings, which forms an important part of the young koala's diet, allowing it to make the transition from milk to eucalyptus leaves, rather like a human baby is fed "mushy" food when it starts to eat solids. Pap is soft and runny and thought to come from the caecum(a blind ended pouch at the junction of the small and large intestines). It allows the mother to pass on micro-organisms present in her own digestive system which are essential to the digestion of eucalyptus leaves.It is also a rich source of protein.

The joey leans out of the pouch opening on the centre of the mother's abdomen to feed on the pap, stretching it open towards the source of the pap. The baby feeds regularly on the pap and as it grows it emerges totally from the pouch and lies on its mother's belly to feed. Eventually it begins to feed upon fresh leaves as it rides on her back. The young koala continues to take milk from its mother until it is about a year old, but as it can no longer fit in the pouch, the mother's teat elongates to protrude from the pouch opening. Young koalas remain with their mothers until the appearance outside the pouch of the next season's joey. It is then time for the previous year's joey to wean and find its own home range. If a female does not reproduce each year, the joey stays with her longer and has a greater chance of survival when it does leave its mother.

Koala with joey
A koala with a very young joey

Interesting Facts about Koalas

  • Koalas are not bears. They are MARSUPIALS, which means that they carry their young in a pouch.
  • The koala has a body length of 60–85 cm (24–33 in) and weighs 4–15 kg (9–33 lb).
  • Koalas have two thumbs on their front paws - to help them climb, to hold onto the tree and to grip their food.
Koalas have two thumbs
Koalas have two thumbs to help them climb
  • Koalas are mostly NOCTURNAL animals. This means that they sleep in the daytime, and move around and feed at night.
  • Koalas' fur is different in different parts of Australia. In the southern parts of Australia it is longer and shaggier than in the north, in order to keep them warm in the cold southern winters.
  • The male Koala has a dark scent gland in the center of his chest. He rubs this on the tree in order to mark his territory.
  • Koalas also communicate with each other by making a noise like a snore and then a belch, known as a "bellow".
  • Koalas on mainland Australia produce on average, one young every two years.
  • When Koalas are born, they are only 2 centimetres long, which is about as big as a jellybean!
  • Koala babies are known as 'joeys'.
A Koala joey rides on its mother's back until it leaves home to take care of itself.
Koala with joey
  • At birth, Koala joeys have no fur and their eyes and ears are still closed.
  • The Koala joey rides in it's mother's pouch for about 5 or 6 months, and drinks milk from its mother's nipple. After that, it rides on its mother's back until it leaves home to take care of itself.
  • There are about 600 varieties of eucalypts. Koalas Australia wide eat only about 120 of these. Koalas in a specific area would prefer to eat only about 4-6 different types.
  • Eucalypts (gumtrees) are both food and homes for the Koalas.
  • An adult koala eats about 1/2 - 1 kilogram of leaves each night.
  • Koalas have a very low metabolic rate for a mammal, which is why they can sleep for up to 20 hours a day!
  • The koala is the only mammal, other than the Greater Glider and Ringtail Possum, which can survive on a diet of eucalyptus leaves.
  • A forest can only have a certain number of Koalas living in it, otherwise they get hungry and sick.
  • 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 Koalas become upset and worried ("stressed") by the loss of their homes, they may get a disease called " Chlamydia".
  • Dogs and cars kill many Koalas each year.
Koala in jeopardy
Koala in jeopardy
  • Koalas are protected by law, but their homes and food aren't.
  • The biggest problem for Koalas is that their bushland (or "habitat") is being cut down to make way for houses.
  • Probably around 80,000 Koalas remain in Australia possibly only as many as 43,000. Most of their habitat has already been lost. This makes it very important to preserve what is left.
  • Koalas are often mistaken for the infamous dropbears of Australian folklore. 😎

The official status of Koalas

In April 2012, the Australian Government declared the Koala as ‘VULNERABLE” under the Federal EPBC Act in New South Wales, the Act and Queensland.  Victoria and South Australia were excluded from the listing.  The Australian Koala Foundation (AKF) believes that the Koala should have been listed in all States.   Research conducted by the AKF strongly suggests the Koala’s conservation status should be upgraded to “CRITICALLY ENDANGERED” in the South East Queensland Bioregion as the Queensland Minister for the Environment has declared them to be “functionally extinct”.

Koalas are in serious decline suffering from the effects of habitat destruction, domestic dog attacks, bushfires and road accidents. The Australian Koala Foundation estimates that there are less than 100,000 Koalas left in the wild, possibly as few as 43,000.

Koala distribution map

Along the eastern coast, Koalas are most abundant on the central and north coast of New South Wales and the south east corner of Queensland. These areas have rapidly expanding urban centres which threaten habitat occupied by Koalas. Local extinctions are occurring, and unless the habitat needs of Koalas are considered now, extinctions will continue to escalate.

In 2017, the AKF believes that the Federal Government is abrogating it’s responsibility for protection of Koala habitat to the States. Then the States often pass principal responsibility to local government and then in AKF’s view, the biodiversity of Australia is just extinguished.  Local government is where most day to day decisions are made about what happens to Koala habitat but where there is often the least amount of resources and expertise in wildlife management or habitat assessment.

Video: Behind The News (BTN) story - Scientists are worried about the effect rising sea levels and deforestation are having on Australia's koala population. The iconic Aussie animal is already listed as vulnerable, but some are concerned things will only get worse. (published Jun 12, 2017)

Sources:

http://www.thekoala.com/koala/

https://www.australiazoo.com.au/our-animals/mammals/koalas

https://www.savethekoala.com/

https://en.wikipedia.org/wiki/Koala

https://www.savethekoala.com/about-koalas/koala-endangered-or-not

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