Conserving Koala Country

Conserving Koala Country

Friday, 6 March 2015

Getting the facts right

The misinformation in the media over the last few days has been frustrating to read. I am writing this blog to set the record straight, clarify the need for the actions of late 2013 and early 2014, and answer a few questions about koala management.

Around 75 koalas were relocated from French Island to Cape Otway in the early 1980s. Most of these probably survived because they were hand-picked healthy individuals that were relocated from manna gum woodland to manna gum woodland. In addition to being similar habitat, the Cape Otway manna gum did not have a resident koala population. These are important points to remember!

In manna gum woodlands, koalas become manna gum specialists and their behaviour is different to what is seen elsewhere. Their ranges are small (less than 1/2 hectare), they tolerate other koalas in close proximity, fecundity is almost 100%, and joeys survive to become breeders themselves. This results in population growth and densities that are seen nowhere else. In addition, in places where fire is suppressed (human intervention) there are no natural regulators of population growth.

These koalas seem to tolerate other koalas in close proximity

This koala (joey on belly) struggles to find enough food
In 2008, there were about 450 hectares of manna gum at Cape Otway adjacent to the vast blue gum/grey gum/mountain ash forests of the Great Otway National Park. By September 2013, there were around 200 hectares of manna gum left. Koalas had defoliated and killed trees to the south and numbers had increased in the north due to koala movement from the south and breeding. Trees began to die but most koalas showed no sign of moving. Female koalas abandoned their joeys and all koalas started eating bark, grass and sometimes dirt. 

On a personal note, I dreaded my weekly visits to Cape Otway because each week I would have to pick up yet another carcass of one (sometimes several) of my study animals. The day I picked up 4 and took another emaciated one to a carer to have euthanased was my lowest. I have not seen anything like it in 25 plus years of working in wildlife management. 

There was a smell of rotting koala in the air. Landholders were suffering extreme stress watching both koalas and trees die. 15 of 20 of my radiocollared animals died, most of those before the government finally stepped in and started putting animals out of their misery. 

I applaud the government for making the difficult decision, especially knowing that there could be significant negative media. Had the media of this week happened back then, 686 koalas would have still died, but their suffering would have been for much longer. I felt incredibly sorry for the team that had the difficult task.

It was not a cull. It was euthanasia of irreversibly sick animals. Healthy animals were released, females given a hormone implant. 

It was not done secretly. It was done in a very public place and hundreds, if not thousands of people were there to witness it. Landholders knew. Prior to the euthanasia, I had tried contacting the media. The few times when my call/email was actually returned, it usually was to say something like "we don't want to get in the way of what needs to be done".

Perhaps if the government had taken action sooner we may have avoided having to take such drastic but necessary action. But in 2013 it was too late for hindsight: the problem was there and needed to be addressed. 

This animal was too weak to climb.
I found some leaves for him

So what are the options for dealing with overabundant koalas at Cape Otway? The following are the only ones that are permitted:

1. Relocation to other forests or zoos? In 2008 there would have been between around 4000 koalas in manna gum. In 2013 there were likely more. These koalas are manna gum specialists and there are studies that show that between 90 and 100% of koalas relocated from manna gum to other forest types die. There is no manna gum left in Victoria that doesn't already have a large number of koalas so there is no manna gum to relocate koalas to. Zoos are not interested in taking adult koalas. Adult koalas straight from the wild are difficult to handle and feed and are stressed around people. Zoos only want joeys or young subadults that they can hand-raise and habituate to people.

2. Fertility control? Very expensive and may only have low effectiveness. However, at this point it really is the only option to stop koalas increasing in number again. It may be more effective than first thought. Results from some of my tracking work suggests that high site fidelity means that there is little movement of koalas within some areas. The government would need to commit to a long-term plan though to address issues of koalas moving in from the neighbouring forests of the Great Otway National Park.

3. Plant more trees? The landholders have been doing this for years and have plans to continue.

4. Let 'nature take its course'? Loss of the manna gum ecosystem may be the final outcome despite all our efforts. Personally, I would like to do whatever possible to avoid that. I hope you agree!


  1. Thank you, Desley, for sharing this information. The media has made a mess of it. It's fantastic of you to get the truth out.

    Linda Dennis
    Fourth Crossing Wildlife

  2. Thank you for your support Linda.

  3. Thanks for sharing this information Desley. It cleared up a lot of things for me. A friend shared it on Facebook and that's how I came across it. If you have time to answer, I'd like to ask a few questions.
    Is there anyone lobbying our government for more manna gum plantations to be created?
    Surely the government needs to take some responsibility for planting these increasingly rare trees and not have that task rest solely on the surrounding landholders?
    Why has it taken so long to discover that fertility control may actually be a viable option?
    In relation to the comment "maybe if the government had of taken action sooner", what action do you speak of?

  4. Thanks for your questions Steve. I'll do my best to answer them:
    1. I agree that the government should take responsibility for creating and restoring koala habitat. I push for that at every opportunity. It should not be left to the landholders to fund it out of their own pockets, especially where mismanagement of koalas has resulted in widespread death of trees. Landholders have been planting trees for years. Last year alone, something like 70,000 trees (mixed species) were planted.

    Unfortunately, just planting trees will not be a solution and may simply increase the area of problems, unless there are other regulators of koala population growth (e.g. fire or disease). Blue gum plantations in Western Victoria are now full of koalas that have moved in from adjacent habitat.

    2. Fertility control - It has not taken a long time to discover this as an option. In fact, fertility control has been used successfully on Kangaroo Island, Mt Eccles National Park, and several islands where koalas have reached unsustainably high densities. The problem is, it's expensive (around $50 per koala plus catching costs, vet fees, program management etc), and because koalas are a long-lived species it takes a long time before populations return to a sustainable level. The Kangaroo Island program has been running since 1997 and in 2007 it was only beginning to make a real difference to habitat condition. Translocation of koalas to manna gum forests in south east SA was also part of that program. Without that, the time until effect may have been longer.

    In a place like Cape Otway effectiveness of fertility control may be limited by the potential for koalas to immigrate from neighbouring forests (>1000 km.sq of koala habitat in the Otway Ranges). However, if the government had have implemented a fertility control program in the early 2000s (and yes, this was suggested back then), it is highly likely we would have avoided the situation in 2013. It is only my recent research (supported by Earthwatch) that has revealed that most population growth within manna gum is due to breeding rather than immigration. My tracking work shows that koalas in manna gum at Cape Otway have considerably high site fidelity, and that movement of koalas into many patches (especially those farthest from the National Park forests) is minimal.

    I am very keen to see the government implement a fertility control program - with fewer koalas, a smaller area over which to work, and in light of our better understanding of koala movements it could be effective and is the only legal option. Habitat management including planting trees and actions to exclude koalas from some trees (to preserve local seed stock) should be part of a management program.

  5. Hey Desley,

    Thanks for putting facts behind this story.

    It has taken the web by storm and only you has actually told the reality.

    Your blog is now getting shared by koala groups widely, so good for you for setting things straight, and also it's a sad story but the truth is slightly better than the media conspiracy theory. I think many people will feel slightly less sad - especially the part about planting 70,000 trees.

    Heart breaking times you had to live through...

    All the best,

  6. Thanks Desley for all your work with the koalas. We appreciate your efforts!