Koalas

     Koalas are not drunk on eucalypt leaves as many people believe.  Instead, the reason for their laid back lifestyle is to conserve energy due to a low nutritional content in their diet.  They are not like a sloth which is unable to move quickly, and they can move quickly if the need arises.  They do sleep 20 hours a day, however this is not in one block.  They continually wake up, have something to eat, and then dose off again.   Koala eat between 500grams and 1 kilogram of leaves per day.  

     Koalas have many adaptations to survive their low energy and highly toxic diet.  They have one of the smallest brains of any land mammal compared to body weight.  Their brain only takes up 60% of their small brain cavity.  They have a very good liver to neutralize the toxins in the leaves they eat.  With the aid of bacteria and a very long digestive tract they get enough nutrition from a very poor but plentiful diet.  They also have one of the best insulating coats of any mammal.  A trait which they were nearly wiped out for.

      Many people are unaware there are three different types of Koala's.  The Northern, Central and Southern Koala.  All have slight differences to suit their environment.  These differences are in size, colour and the length of their fur.  Adult Koalas have no natural predators, their coat colour does not camouflage them in the trees like many believe.  The colour helps in heat absorption or reflection.  Koalas do not drink water.  They get all their moisture needs from the leaves they eat.  On rare occasions they will drink but it is generally a sign of sickness/ stress.

     The Northern Koala lives in Queensland and Northern NSW.  It is always warm.  Their coats are lighter in color to help reflect the sun, so that they do not dehydrate.  They are the smallest of the Koalas with males reaching 6kg.  The smaller size increases their surface to volume ration and they loose heat better.  They also have shorter fur and lack the larges amounts of fur on their ears.  Another way to increase heat loss.

     The Southern Koala lives in Victoria and into South Australia.  It gets quite cold, especially during winter.  As it takes a lot of energy to keep warm they have adaptations to retain body heat.  Their dark coats absorb the sun and they warm up very quickly.  Their larger size 12kg in males, twice that of their northern cousins, reduces the surface area to volume ratio and retains body heat.  They also have beautiful fluffy coats to keep them warm, making them the most attractive of the Koalas.

     The Central Koala lives in NSW.  As this in between the two types they have traits in between the two.  Males get to around 10kg, coat colour is in between the two and they are not as fluffy as their southern cousins.

     Sadly since European settlement, Koalas have suffered.  In the 1900's they were hunted close to extinction.  They were protected and today the population is in the hundreds of thousands.  They are not on the verge of extinction like people are made to believe.  As they have a very large range, they have different problems.  In Queensland due to the urban sprawl and habitat clearing they are very vulnerable.  We run them over in our cars, they get attacked by dogs and they don't get enough to eat.  In NSW the populations are very stable.  In Victoria and South Australia they have a problem with overpopulation.  The areas of habitat where they are found is very patchy and some quite small.  As they have no natural predators they breed up and breed up and have no where to go.  Eventfully they begin to defoliate the trees and the trees start to die.  Travelling around you will see areas where this has happened like Kennett River.  The damage is also masked by the other trees they do not eat.  These trees look healthy, which they are.  If you look at the trees they are eating, it is another story.        

     Sadly there exists a real concern for their welfare in wild populations in southern Australia, where there are literally too many koalas for their habitat to sustain.  In extreme circumstances, they are defoliating the trees and starving.

     Although Koalas are not endangered they are used to save areas of habitat for other animals.  They are called a Flagship species.  People are willing to provide money to save them rather than a small native mouse that might need conserving.  Money is provided to save the Koalas, but in turn saves the mouse.

     Koalas are marsupials and have a gestation of 35 days.  The baby then has to make it's way into the pouch where it stays for 6 months.  It then rides on it's mum's back for a further few months.

© Fauna Australia Wildlife Retreat 2009