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Koalas and Bushfire

Why choose koalas for special treatment when many other species are in deep trouble because of the bushfire?

There is a basic principle called ‘umbrella species’ that is a great conservation management tool. The idea is that one species is key to managing many others and it works brilliantly with koalas.

Koalas have a basic social structure of a dominant male with a harem of females, usually about four to six, with juveniles and sub-dominant males. Koalas are highly territorial and the home range varies with quality of the habitat. Other species such as bearded dragon lizards have the same social structure and similar home range size.

Across the landscape koalas live in home range patches with ‘empty’ gaps between them. As juveniles mature they need somewhere to go, in a process called dispersal. Habitat may be suitable for a family group but unoccupied, at least for the short term. That ‘empty’ habitat has a very important role for dispersal, for holding maturing males and as replacement habitat if a family group suffers a disturbance to their habitat. What makes it work is connectivity across the landscape. Highways and domestic dogs can be significant koala killers.

Populations have to be large enough as connected families across the landscape that dispersed juveniles can make or join a new breeding family and not suffer inbreeding, with poor genetic consequences. Young males travel quickly, 20km to 100km in a week, across the landscape if there are no barriers to movement. Females travel not much beyond their parents’ home range. Five hundred breeding animals is really a minimum and five thousand is safer for genetic health of a population.

How does that help all the other species? Koalas occupy a wide range of habitat types including woodlands and forests. If a sufficiently large area, with good connectivity, is maintained for koalas, then almost every other species using the same habitat will enjoy the same protection. A new NSW National Park near Goulburn NSW was created from marginal farmland and is managed to retain some cattle grazing. It is possible to manage a koala landscape so as to preclude wildfire, which of course ends up protecting many other species of both plants and animals. Grazing provides income from the land and the land returns ecosystem services of clean air, clean water, climate amelioration, biodiversity for crop pollination, honey production and recreation.

Once that habitat structure is established then other controls such as removing domestic dogs, feral cats, foxes and deer can be introduced. Thus, raising the status of koalas to ‘endangered’ status and managing them at a population level will benefit all the biodiversity under that landscape and local ‘umbrella’.

On a per animal basis the Australian Koala Foundation said years ago that the value of each koala to the national tourism economy is one million dollars. That is 9,000 jobs and one billion dollars every year for Australia. Now that we may have lost one third of the population to wildfire, that per animal value has just shot up significantly. Its time for some serious investment.

It's not just koalas that say “No Tree, No Me!”

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