Koala Research & Education

In the Wild – coastal females 15-18 years; males 10-15 years. In harsher koala habitats, their life span can be less. In captivity both can live 15+ years. We hold the World Record for the Oldest Living koala - a female called “Birthday Girl” who died in 2011 at the age of 25 years.

Koalas sleep approximately 18 hours out of 24. This is an evolutionary strategy to conserve their energy as the eucalypt leaf is so low in nutrients/energy value.

An adult koala can eat up to a kilo of leaf over a 24 hour period. They often browse and eat for an hour or so, then sleep then feed again hours later.

There are approximately 900 species of eucalypt in Australia – in each region koalas are known to feed on anywhere up to 100 different species. Koalas normally have around 10 species that are their main preferred food source. They eat new and mature leaves, buds, flowers and at times bark but the bulk of their diet consists of leaves.

An adult koala can poo up to 200 pellets in 24 hours.

Domestic dogs are the main predator of koalas. Powerful Owls, Lace Monitors, and Wedge tail Eagles. The number one predator of koalas is the human species.

When the joey is about one year old it is no longer dependent on its mother and is fully able to fend for itself. Joeys are able to disperse from the maternal home range from 12 months on.

Adult koalas live in a home range and stay there for their entire lives unless age illness or a higher ranking animal removes them. Therefore adult koalas must be released back to their point of capture or very close by. It is very similar to humans owning a house and backyard.

Once joeys leave their mothers home range they become juveniles (like human teenagers) Juvenile male koalas that leave their maternal home ranges often struggle to find unoccupied habitat and tend to live in very poor country for the first few years until they are big enough to challenge bigger, older males. Juvenile females can also struggle to find unoccupied habitat but are usually accepted much more into new koala populations. These young koalas usually disperse well away into other new locations eventually finding new populations and new home ranges. This behavior encourages good genetic diversity.

The size of a koalas home range is dictated by the age, sex, health and quality of the habitat. Koalas also belong to a social hierarchy in their population. For example coastal koalas in NSW are found in areas of good soil, high rainfall and in undisturbed habitat and have a high level of the quality food trees. Higher ranking adult male koalas’ home ranges can be up to 100 hectares for one animal, with higher ranking females’ home ranges being slightly smaller. Very old and unwell koalas tend to get pushed out of their home ranges and are often located in poorer harsher areas. Radio tracking of koalas over a 12 month period has found that the majority of koalas tend to partition their home ranges into summer and winter living in either end depending on the season. This makes sense – living in the cool gullies in summer and on the warmer ridges in winter. Many a home owner has said “our resident koala has been gone for months and he has just come back” – this is why. Mountain koalas found on the Great Dividing range are likely to have slightly larger home ranges and koalas on the western plains in harsher conditions often can have even bigger home ranges as their trees are more scattered.

The koalas diet is the same in both summer and winter as eucalypts are not deciduous. In spring and early summer, eucalypts have a big flush of growth with the young tips of the leaves being highly prized by koalas. Snow can fall in the mountain areas of NSW and Victoria with koalas usually moving down the slopes during winter getting well below the snow line.

Treating wild koalas that come into care can be very expensive. Costs include veterinary care, surgery, radiography (x rays) diagnostic imaging, pathology, drugs and daily care. The Koala Hospital has a number of paid staff who run the hospital along with paid leaf collectors who harvest fresh eucalypt leaf daily. The remainder of the large number of jobs required to run a successful hospital are done by the 150 volunteers. The hospital could not survive without their wonderful work. The vast majority of the hospitals funding comes from the generosity of the public. The remainder comes from adopt a wild koala program and from sale of koala related merchandise in our shop.

The koala is admitted into the hospital and is given an initial examination depending on the reason for admission. If the koala has been hit by a car or attacked by a dog it gets immediate treatment. A koala suffering from a disease or an unknown issue is usually left to “settle” for the first 24 hours. The following day the koala goes under a general anaesthetic and is given a full examination which includes blood, pathology and sample collection, ultrasound, and then a treatment plan is put into action. Some koalas arrive in chronic severely ill states and are euthanased on welfare grounds as these koalas tend to be beyond treatment. If the koala does not have chronic advanced disease we will commence treatment. The current treatment plan for the disease chlamydia includes a six week course of medications and in some cases minor surgery. At the end of six weeks the koala is then left alone in the enclosure to recuperate for two weeks. We then re-anaethetise the koala to see if the disease has returned (via a number of tests) and if ok, the koala is ear-tagged, microchipped and then released back to where it was picked up.

Each koala is weighed, sexed, aged and measured on admission. Every koala has its own admission card and patient data. Everything done to the koala is recorded both on their charts and on a data base. The data base holds full patient information and the data goes back to 1973. Once koalas are ready for release they are ear tagged and microchipped. If the koala is captured years later and brought into the hospital, staff can pull up the koalas chart and immediately know its clinical history. Some koalas are warmly called “repeat offenders” as they seem to continually be admitted to the hospital over their lifetime. The majority of these cases occur because these koalas have to continually battle with roads, dogs and all the human obstacles that urban and rural environments produce.

Fossil evidence has shown that ancestral koalas were part of the mega fauna (giant marsupials) millions of years ago. Modern koalas began to evolve and adapt to the drying of the Australian continent in line with the rise of the eucalypts. Consequently the koalas we see today have been in existence for a very, very long time.