In some parts of their natural range, koala populations are on the decline. However, across South Australia, koala populations are mostly stable, increasing or over-abundant.
Over-abundance means that koala numbers in a particular area have increased to such an extent that their habitat can no longer support them.
In such a situation, managing koala populations may be necessary to avoid negatively affecting native flora and fauna (including koalas that could potentially starve due to limited resources).
Culling koalas and introducing diseases are not supported as methods of controlling koala populations. Instead, a mix of management techniques are in use, including sterilisation (temporal or permanent), relocation, management of their habitat (installing tree rings, etc.) and monitoring koala density and tree conditions.
Koalas in the Adelaide and Mount Lofty Ranges
Results from the Great Koala Count of 2012 and 2016 as well as on-ground surveys across the Adelaide and Mount Lofty Ranges region indicated that koala numbers are increasing to an unsustainable level in certain areas of this region.
Koalas have been managed using hormone-implant contraception in some areas of high koala density, where over-browsing is occurring, in the Adelaide and Mount Lofty Ranges region.
Koalas on Kangaroo Island
In 1997, the Kangaroo Island Koala Management Program was developed to reduce the island's koala populations to a sustainable level. This program was the result of an independent assessment of the increasing koala populations on the island and its impact on native vegetation, particularly manna gums.
The aim of this program is to reduce the island’s koala populations to a sustainable level.
Since the project began, more than 13,500 koalas have been sterilised or contracepted, and about 3800 of these sterilised koalas were translocated to their historic range in the South East of South Australia, making it one of the largest fertility control projects in the world.
In 2015 there were an estimated 25,000 koalas in native vegetation on Kangaroo Island and an additional 23,000 koalas estimated to be on the island’s commercial blue gum plantations.
The South Australian Government is now working to determine the impact of the 2019-20 Kangaroo Island bushfires to the Kangaroo Island koala populations and understand if any changes are needed in the ongoing management of these populations.
Read the report on Rapid assessment: Kangaroo Island Koala population update following the 2019–20 summer bushfires .