Koalas are short and stocky animals with dense, woolly fur which is light grey in the northern part of the range and brownish grey in the south. The underside is white, while the large flat nose is black. Northern animals are also much smaller than their Victorian equivalents, males of which may reach over 80cm in length and weigh 14kg. Koalas have very sharp claws, which are excellent for climbing and can be used in defence. Koalas are mainly nocturnal animals that spend the day asleep in the fork of the tree. They are solitary animals and will aggressively protect their individual territories. Fights can be extremely violent with opponents vigorously scratching and biting each other.
Because of their limited diet, the koala is only found in the eucalypt forests of eastern Queensland, New South Wales and Victoria, as well as the far south-eastern part of South Australia. They move around regularly, travelling between favourite food trees. They do not make any type of nest or shelter.
Koalas have an exclusive diet of eucalyptus leaves and their digestive tract is specifically designed to cope not only with the low nutrition-high fibre characteristics of the foliage but also the toxic compounds that are contained in the leaves. They do not eat all eucalypt species. Of the many hundreds of species, koalas only eat around 40 on a regular basis and in any given area usually three or four species comprise the bulk of the diet. The old story that koalas are lethargic because they are ‘stoned’ on eucalyptus is untrue. This inactivity is merely an energy-saving adaptation to their poor diet.
Most koala mating occurs between the months of October and January. After a gestation period of around 35 days, the jellybean-sized baby climbs up into the mother’s backward-facing pouch and attaches to a teat. The joeys stay in their mothers’ pouch for about six months, then the baby climbs onto their mothers back and rides around in safety for a further six months gradually learning to eat their leafy diet. They reach sexual maturity at the age of three or four years and live for 16-18 years in captivity but probably much less in the wild.