Conserving Koala Country

Conserving Koala Country

Thursday, 24 September 2015

To translocate or not to translocate?


This is a question that is currently in the spotlight.

In my opinion, translocation should ONLY be undertaken as a last resort when:
  • reducing the koala population in an area is critical to saving habitat, and
  • it is likely that translocated koalas will have a high probability of survival.
The better option would be for governments to implement long-term management actions (fertility control and habitat management) prior to emergency situations arising. That advice was ignored for Cape Otway so unfortunately, translocation of koalas is now the only option for saving some of our manna gum woodlands and all of the wildlife it supports. It also may be the only option for avoiding more koala starvation and more koala euthanasia.

  video
When a situation is allowed to get this bad, translocation may be the only answer

But do translocated koalas survive? It depends on a lot of factors. A few key things to be considered are:
  • Koalas should be healthy and relatively young,
  • The receiving habitat should contain koala food trees in healthy condition,
  • The receiving location should have a climate similar to the original site (that's why interstate translocations should be avoided),
  • Will there be any impacts of translocated koalas on the receiving habitat (including the resident koala population)? For example, koalas should not be translocated to areas like South Gippsland where koalas have more diverse genetics or to areas where there is a high incidence of disease.

Other translocations

Translocation has been a component of other long-term koala management programs. While working on the Kangaroo Island Koala Management Program, colleagues and I conducted research trials out of concern for the welfare of koalas being translocated to the south-east of mainland South Australia. We radio collared a number of koalas that were surgically-sterilised and translocated, and also radio collared some surgically-sterilised koalas remaining on the Island.

If you are interested in the full details of our study, we published the results in The Journal of Wildlife Management (Whisson et al. 2012. 'Translocation of overabundant species: Implications for translocated individuals', http://onlinelibrary.wiley.com/doi/10.1002/jwmg.401/abstract).

To summarise our main findings:
  • We observed low mortality in the first three months following translocation but 37.5% translocated koalas were dead after 12 months compared to none in the control group that remained on the island.
  • Translocated koalas moved greater distances than those that remained on the island. Some individuals moved up to 10km within the first three months post-translocation.
Clearly, translocated koalas were negatively impacted and this is why I believe that translocation should be a last-resort action only. An 'acceptable' level of mortality also should be decided on prior to large-scale translocations occurring.


So what about translocation of koalas in Victoria?

Obviously koalas can survive translocation (most koala populations in Victoria have resulted from koalas translocated from island populations) but under what conditions and how many koalas survive the process? Surprisingly, despite the tens of thousands of koalas that have been translocated in Victoria over the years, to my knowledge there only have been a few studies of koala survival and the results appear only in draft reports. In some cases mortality has been high (around 90% translocated koalas dying) and this is why the government has been reluctant to use the approach for management of koalas at Cape Otway.

However, the reasons for such high mortality in some translocations aren't clear. Is it that koalas can't adapt to new food sources (when moved from manna gum to other forest types), or is it that they have been stressed by their treatment (surgical or hormone implant), or are they being moved to unsuitable habitat?

Hopefully some of these questions will be answered by the current trial being conducted by the government, and that the koalas in the trial survive. I also hope that the government learns from this situation and develops long-term management strategies for koalas and their habitats to avoid having to use translocation as a last-resort management tool.

Monday, 14 September 2015

Government announces imminent management actions for Cape Otway koalas

Today, the Victorian government issued a media release about upcoming management actions for koalas at Cape Otway. The program will involve checking the health of 300 to 400 koalas, euthanasing any koalas found to be in poor condition, and initiating a study to examine the potential to translocate koalas to other forest in the Otways.

This is welcome news!

Habitats at Cape Otway are continuing to decline under the browsing pressure of so many koalas. In one of our study sites, koala densities have climbed back to 9 koalas per hectare, and the trees are showing considerable stress. Although it may be too late to save much of the manna gum woodland, it may be possible to prevent the suffering of many koalas. A lot depends on koalas surviving the translocation trial. If there is high mortality of koalas in the trial, then the only option is fertility control which is too slow acting to avoid another population crash.

Manna Gum Drive - trees continuing to decline

Without translocation, this mum and joey are unlikely to survive for long


Our research which is generously funded by Earthwatch Australia and supported by Earthwatch volunteers, continues to provide important information on koala densities and habitat condition across the Cape, and has been critical in informing the government's management actions. In fact, as I write this post, a team of Earthwatchers are surveying our long-term monitoring sites. Future teams will continue to monitor those sites and participate in studies of koala behaviour and their response to their ever-changing landscape.

Planting by Earthwatchers to rebuild koala habitat