You are here

Hans Brunner scientific response re ecosystem need for top predators, Mornington Peninsula

Mornington Peninsula[1] The writer of an article about ecosystem need for top predators claims that "Observations on trees and experience with possum guards by the author indicate that possums are the major cause of tree decline on the Mornington Peninsula ..."

Hans Brunner: I am somewhat alarmed that a highly respected ecologist, Dr. Jeff Yugovic, can declare that possums on the peninsula are in plague proportions (published in the journal Indigenous, “Do Ecosystems need top predators?”) and that this was supported by Carol Shelton on behalf of Mt Eliza Association for Environment in form of a press release. There are probably many other people who would agree with Yugovic and Shelton merely because they don’t like possums jumping about on their roofs during the night.

I myself believe in scientific evidence.

Where are the regular spotlight counts that establish the real numbers of possums compared to the number of trees available to them in a given area?

Where are the true numbers of trees that actually die from possum browsing compared with trees dying from the many other reasons?

I have inspected lots of sick-looking trees without finding possum droppings under them and no signs of browsing. I can find more possum droppings in built-up areas under power-lines used by possums than under trees and in those areas all the trees look healthy.

The assumption that there is a plague of possums on the Mornington Peninsula resulting in the destruction of the tree canopy is in my view only a hypothetical observation and is definitely not based on rigorous scientific and unbiased research.

Over the last three years Victoria has experienced each year one or two severe heat waves. As a result, thousands of possums died in those years from heat exhaustion. So, where now is this “plague” of them?

With more heat-waves predicted in the future they may even become endangered.

The suggestion that we overdo predator control and that, on the contrary, we need more foxes, cats and dogs to reduce possums is totally irresponsible.

Because of these predators - foxes, cats and dogs - on our Peninsula, nine (9) native mammalian species have already become extinct, five (5) species have become extremely rare and another two (2) are endangered. And this is just mammals!

This same ratio or worse applies to species of birds, reptiles and amphibians.

While I think, and hopefully all of us agree, that in large natural environmental ecosystems a balance between predator and prey species is essential, here on the Peninsula the situation is very, very different.

The expectation that an increase of predators may reduce a few possums would surely be badly out-weighed by the risk of losing proportionally even more of our rare, native wildlife species.

Putting flexible plastic sheets around the trunk of trees, to be effective, would require being done to every tree on the Peninsula, because if possums can’t go up one tree they would soon find another one. Even if this were possible, practical, or desirable, the risk is that it will also exclude koalas, sugar gliders, marsupial mice and reptiles accessing these trees in the same manner as possums.

So, please don’t make possums the scapegoat and declare war on them!

Hans Brunner


[1] The Mornington Peninsula is in Victoria, Australia.
Comment by editor: It was declared part of the UN Biosphere series a few years ago, in one of many attempts to save its biodiversity and considerable natural ammenity, but despite this, it is sadly being covered in roads and housing by successive troglodyte Victorian governments.

Originally published under another title on 2013-03-26 20:40:25 +1000.


This so obvious it hardly needs saying, but the real pest species is the human who now seems not to have any predators at all except the occasional crocodile or shark. Humans are inexorably spreading all over places that our native fauna called home. Humans do not just damage trees and compromise their survival, they annihilate them altogether to make way for development. They leave areas effectively sterile with respect to plant and animal life." Dogs and cats can not be considered separately from humans. Wherever you have humans you have cats and dogs. We love them but we do not act responsibility enough with them as a society.The human dog and cat package is deadly for wild life. I would need real evidence that possums have destroyed trees before I set the carnivores onto them! We are becoming irrational with respect to possums.In recent years in an urban park, possums were blamed for transmitting fusarium palm wilt and excluded from the palm trees where they slept during the day and had done for about 50 years. Expert advice obtained was that possums do not spread this disease and that the palms in question were not suffering from it anyway. The possums were then evicted, on another pretext - that they were eating the palm fronds. The palms look exactly the same to me as they did 6 years ago when possum exclusion bands were installed. If the possums were eating palm fronds it could not have been enough to worry the tree! Real science and stabilisation of the human population are desperately needed for the sake of the remainder of our wild life.

Forget the "plague" of possums or any other native animal in Australia! Conservationist (and infamous patron of the Optimum Population Trust) David Attenborough recently said that humans, as a species, are a “plague” on the environment. He therefore proposed limits to human populations, “or nature will do it for us.”

On the official website of the Prince of Wales, prince Charles commended the Ehrlich’s latest population study published in the Proceedings of the Royal Society on January 8 of this year, calling among other things for globally provided “back-up abortions” to avert overpopulation catastrophe. The prince writes:

“We do, in fact, have all the tools, assets and knowledge to avoid the collapse of which this report warns, but only if we act decisively now.”

Attenborough says that "maybe it is time that instead of controlling the environment for the benefit of the population, we should control the population to ensure the survival of the environment," in a letter to John Guillebaud, Professor of Family Planning and Reproductive Health at University College London.

"Based on the Optimum Population Trust's findings, it is proposed that family planning methods should be a primary tool in the optimum strategy for reducing carbon emissions," the report said.

While much of the projected growth in human population is likely to come from the developing world, it is the lifestyle enjoyed by many in the West that has the most impact on the planet.

Human population blindness stops seeing the plague we ourselves are, and instead projecting the problems onto wildlife, overconsumption or even capitalism.

I take it that Mornington Peninsula Botanist Jeff Yugovic is not suggesting that we need more foxes, cats and dogs on Mornington Peninsula? That would be as good as admitting defeat and surrendering any ways to manage our environment. It would open the door to complete mayhem and destruction, and would only denude the area of any wildlife habitat.

The "plague" of native possums is because habitats such as trees and canopy have been destroyed by clearing, infrastructure and urban sprawl. The Peninsula Link has increased the number of native animals being slaughtered on the road. It's not evidence for a "plague", but their vulnerability and exposure.

It seems to me to be like blaming the victims instead of pointing the finger at the real source of disaster - excessive human behaviours and greed for growth.