Habitat: Koalas are strictly arboreal mammals, living in and feeding on the leaves of eucalyptus trees. The two most important features that define a koala's habitat are the presence of primary tree species prefered by koalas and the presence of other koalas. These two factors are essential in determining suitable habitats for koala populations. Koalas predominately live in eucalyptus forests along the East coast of Australia. The map below provides a general idea of the dispersion of koala populations along the coast. Koalas are very specific about the species of trees that are present within their habitats.

Some of the latest research on koalas shows that forests or areas will not support socially stable koala populations unless there are at least one or two primary or favourite tree species present. This information has become very important in efforts to conserve koala populations. The presence of other koalas is also critical in establishing a habitat suitable for koalas. Koalas are very social animals, and they rely on interaction with others. Therefore, suitable koala habitats are largely determined by the presence of primary eucalypt species and the presence of other koalas (Australian Koala Foundation).

Population: Koala populations are characterized by complex social interactions. Koalas are social animals, but they are also very territorial. In the wild, koalas exist in stable breeding groups, but each member of the society maintains its own home range. A koala's home range consists of several trees that provide the animal with food, shelter, and a place for social interaction. Where socially stable koala populations occur, the home ranges of individual koalas overlap with those of their neighbor. The trees found in these overlapping areas are very important within koala populations becuase most of the social interaction takes place in these critical trees. Individual koalas will indicate their home range by scratching and scent marking trees. Interestingly, when a member of the population has passed away, other koalas usually will not move into the newly available space for about a year. This is approximately how long it takes for the scents and scrathes of the previous koala to disappear (Australian Koala Foundation).

Diet: Along with the Greater Glider and the Ringtail Possum, the koala is one of the only animals that is capable of surviving on a diet of eucalyptus leaves. Eucalyptus leaves are extremely fibrous and low in nutrition, and are poisonous to most animals. There are over 600 different types of ecualyptus trees in Australia , but koalas will only eat from a very small percentage of these trees. Adult koalas can eat approximately 2.5 pounds of food a day. Koalas are fussy eaters and have strong preferences for various types of eucalyptus leaves. To cope with this poorly balanced diet, koalas have evolved many specialized adaptations. Koalas will sometimes eat leaves of non-eucalypt trees, but this is often the result of a lack of preferred food sources. Another interesting point about koalas is the fact that they seldom drink. Koalas generally obtain a substantial amount of water through their diet and rarely have to drink water (Australian Koala Foundation).

Behavior: Eucalyptus trees provide koalas with almost all of their basic needs. The leaves from different species of eucalyptus trees are the koala's primary source of nourishment and the trees provide protection from natural predators lurking below. Koalas do not build nests or shelters in trees like many other arboreal animals, yet they hardly ever come down to the ground. Generally, the only time koalas venture to the ground is to switch trees. Because of their low quality diet, koalas are relatively sedentary and they conserve their energy through their behavior. It is a common myth that koalas become slightly intoxicated by the chemicals in the eucalyptus leaves. There is actually no evidence to support this claim which is sometimes used to try and explain the koalas apparently comatose and lethargic behavior. Koalas have a very relaxed lifestyle, and as you can see, they choose to simply wedge themselves in the forks of trees where they spend a majority of their day resting and sleeping. This behavior, however, is a result of their extremely low metabolic rate and low energy requirements. Koalas spend approximately 16-18 hours a day sleeping. As mentioned before, koalas are completely arboreal. They are also mainly nocturnal, and tend to be most active just after sunset (University of Michigan Museum of Zoology).

Back to Hot Topics in Animal Physiology

This page was created as an assignment for Animal Physiology at Davidson College. If you have any questions, you can e-mail me at cocrawford@davidson.edu.

Click here to return to the homepage.