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Marsupial extinctions: don’t blame the dingoes

The humble dingo has become something of a scapegoat since its arrival in Australia just 4000 years ago. It is widely blamed for the disappearance of thylacines (also known as Tasmanian tigers) and devils…

Top dog, but new research shows the dingo did not kill off its marsupial competitors. Jarrod Amoore/Wikimedia Commons

The humble dingo has become something of a scapegoat since its arrival in Australia just 4000 years ago. It is widely blamed for the disappearance of thylacines (also known as Tasmanian tigers) and devils from the mainland - an event that left Tasmania as their sole refuge.

The hypothesis is that when dingoes spread through the mainland, they were smarter, faster and more versatile predators than their marsupial counterparts, who lost the battle for survival.

But our analysis might yet earn the dingo a reprieve. We have found evidence that - as with earlier Australian extinction events - humans are the more likely culprits.

Land of the giants

When humans first got to Australia around 50,000 years ago they found a land full of giant animals. There were herbivores like the rhino-sized diprotodon, huge kangaroos, a bird more than twice the size of the emu, and many others. And there were large predators to match. The formidable marsupial lion was the biggest at around 100 kg, but alongside it were other more modestly sized predators, including the thylacine and devil.

The downsizing of Australian wildlife diversity happened in two steps. First, most of the giant animals disappeared in an event known as the Pleistocene megafaunal extinction. They were probably gone by around 40,000 years ago.

The thylacine and devil survived this event, but some time within the last few thousand years, both disappeared from mainland Australia, to hang on only in Tasmania (hence the devil’s modern moniker: the Tasmanian devil).

The thylacine is extinct, but at least it survived long enough to be photographed. Wikimedia Commons

What caused these extinctions is controversial. Most evidence points to human impact as the main driver of the earlier megafaunal extinction, probably through over-hunting of big and slow-breeding prey. But other factors have also been suggested, such as climate change and landscape burning by people.

In contrast, the more recent mainland extinction of the thylacine and devil is widely viewed as the direct result of the dingo’s arrival on the scene.

Enter the dingo

Dingoes are descended from Asian wolves and were presumably widely transported as semi-domestic animals by seafaring people colonising the Pacific. They made landfall in northern Australia some 4000 years ago and quickly spread to all corners of the continent – but not Tasmania.

The rough coincidence of the dingo’s arrival with the extinction of the two largest marsupial carnivores suggests the natives were undone by a superior competitor. Maybe the dingo was a better hunter; perhaps it was also more aggressive, and killed them off. The fact that thylacines and devils survived on the only large chunk of Australia not reached by the dingo is pretty strong circumstantial evidence for this idea.

The Tasmanian devil is still with us, despite being wiped out from the mainland millennia ago. Wayne McLean/Wikimedia Commons

But there is another possibility. Evidence has been slowly building that Australia’s human population dramatically changed its behaviour during the past 4,000 years.

Hunting and gathering strategies became more elaborate and probably more efficient, and people became less nomadic. As a result, the population grew, possibly increasing more than threefold between 2000 BC and European arrival.

More people, with better hunting gear, would have had two impacts on thylacines and devils. More would have been killed – we know from other evidence that both species were hunted. At the same time, their prey populations would have been reduced by people. One or both of these factors could have sent them extinct. Crucially, this change in the human population seems not to have happened in Tasmania.

It’s also possible that climate change played a role, through increased variability due to El Niño events. This probably also had bigger impacts on mainland Australia than Tasmania.

New approach

How can we tell which of these factors was the most important in sending the marsupial carnivores extinct? It is hard to think of any type of archaeological or fossil evidence that could distinguish humans or dingoes as the main cause, or test the role of climate variability. The problem is especially thorny because all these factors might have interacted to cause extinction.

Our study, also highlighted in the journal Science), took a new approach. We created a mathematical model of the interactions among predators (people, dingoes, thylacines and devils) and prey (represented by kangaroos) in prehistoric Australia. We also factored in the effects of variable rainfall on vegetation, and knock-on effects on animals. Then we experimented with the model to test which factors had the largest impacts on abundance of thylacine and devils.

The answer was surprisingly clear. The most influential factor in the decline of the marsupial carnivores was human population growth reducing the abundance of their prey.

The other factors - dingoes, climate, and direct hunting of thylacines and devils by people - all increased the likelihood of extinction, but were far less important.

So what have we learned? First, increasing human population size was probably having profound effects on Australian ecosystems for several thousand years before the arrival of Europeans. There is less reason than ever to think that the landscapes seen by the first white settlers represent some kind of stable state of nature in Australia.

Second, we probably need to rethink the role of the dingo in Australian ecology. Rather than wiping out the thylacine and devil, the dingo might simply have replaced them in the ecosystems of mainland Australia, taking over their roles of top predator and scavenger. These roles are significant. As modern societies in Europe and North America are re-discovering, there can be many benefits to having large carnivores in the landscape.

The evidence is growing that without dingoes, Australian ecosystems would be in a lot worse shape than they already are.

Join the conversation

34 Comments sorted by

  1. John Newlands

    tree changer

    Strangely I discussed the demise of the thylacine only yesterday with some English tourists sitting in a double decker bus. The bus went past the gates of Beaumaris Zoo where the last captive animal died of neglect in 1936. Earlier the bus went to Cascade Brewery where the thylacine is a marketing symbol.

    Here's an alternative theory; the thylacine would have died out anyway.The same would probably be true of the Tasmanian Devil which had the good fortune to hang on until human intervention arrested its decline. The thylacine was a natural genetic experiment that was ill adapted to change generally. Perhaps humans wrongly thought they were sheep killers like dingoes or the pelts were a novel trophy. The arrival of human hunting and dogs was the last straw. To survive it would have needed no guns, no dogs, no cars and protected areas with hand feeding.

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    1. Scott Morris

      logged in via Facebook

      In reply to John Newlands

      There's a good book on the subject of the Tyger that makes for an interesting read and is strongly referenced and researched: "Thylacine: The tragic tale of the tasmanian tiger". If you have the inclination, it's well worth a read to see how your theory may be somewhat misguided with the intrinsic impact european settlement had on the Thylacine and subsequently the Devil that depends on scavenging meat remains for food.

      I suggest that this theory of europeans 'saving' the Devil is correct in the context of the loss of the Thylacine. It would not be necessary had there still been a Thylacine upon which the Devil could scavenge its diet. There is no similar large predator in Tasmania to fulfil this role and as the Devil is ill equipped to evolve into a predator in less than 70 years, its fate was sealed by man and the extermination of the Thylacine.

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  2. Chris Owens

    Professional

    What chance is there for the dingo and the associated benefits for biodiversity when farmers insist on eradication where ever it occurs?

    Also what is the anticipated outcome of the trial reintroduction of the devil in places like Wilsons Prom without dingo/human competition?

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  3. Jim Inglis

    retired

    A good article. Yes, I agree that the Thylacine, our true apex predator, typical of the less aggressive marsupials, was not up to the changes that occurred in Australia during the last few thousand years and that, c/w the arrival of the dingo put paid to its chances of survival.

    This article shows how the dingo, like other placental predators in other parts of the world is a smarter, more aggressive predator than any predator our native wildlife ever evolved with.

    But the dingo is still as…

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    1. Henry Verberne

      Former IT Professional

      In reply to Jim Inglis

      Seems you either did not absorb the main points of the article or have evidence of your own that dingos are the main culprit in the loss of native wildlife.

      Fine, but where is the evidence for your assertions?

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    2. Jim Inglis

      retired

      In reply to Henry Verberne

      Thanks Henry. The chapter on the Thylacine, sadly is long closed but the one on the dingo is vitally demanding if we value our natives.

      One question I would like to see answered by science is:

      There has been a fantastic opportunity on Fraser Island over the last 40 years for a detailed study of the effect of the dingo as a replacement of the Thylacine on native wildlife as its numbers have increased and the wildlife numbers have decreased in this newly declared NP and world heritage area.

      Why hasn't it been done?

      I suspect it is a bit like the science of AGW.

      When the professors believe one thing you ain't gonna get your PhD by rocking the boat.

      This is just another reason why I am a science sceptic.

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    3. Henry Verberne

      Former IT Professional

      In reply to Jim Inglis

      Actually Jim, I suspect that at least when it comes FI you may be on to something. An island like that could lead to a predator like the dingo eating itself out of house nad home so to speak.

      But do not then extrapolate that to AGW, I continue to believe you are mis-guided there as the science is infinitely more researched and supported by multiple lines of evidence than the science associated with dingoes.

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    4. Mike Swinbourne

      logged in via Facebook

      In reply to Jim Inglis

      "...This is just another reason why I am a science sceptic....

      No Jim, you are a science denier. Your statements about climate change and the dingo are testament to that And you might want to go back and read the end of the article again - you know, the bit where four eminent wildlife researchers and experts said this:

      "....The evidence is growing that without dingoes, Australian ecosystems would be in a lot worse shape than they already are..."

      But of course, I am sure you disagree, given that you have taken a few holidays to Fraser Island and seen dingoes.

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    5. Jim Inglis

      retired

      In reply to Mike Swinbourne

      "No Jim, you are a science denier."

      Answer me a couple of simple questions Mike:

      Have YOU ever been to Fraser Island and studied the state of the native wildlife?

      You know, got a list of the natives from the ranger and walked around the dunes checking for skats, tracks etc.?

      As in performed your own scientific study on the wildlife there because you couldn't find anyone who had?

      What? haven't done that hey Mike?

      Happy to deny that bit of science and just agree with what they tell you?

      What does that make you then?

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    6. Mike Swinbourne

      logged in via Facebook

      In reply to Jim Inglis

      ".....You know, got a list of the natives from the ranger and walked around the dunes checking for skats, tracks etc.?...As in performed your own scientific study on the wildlife there because you couldn't find anyone who had?..."

      Hate to break this to you Jim, but 'getting a list' from the ranger and walking around is not a scientific study. Unless you can tell me a few things:
      What sort of transect did you walk?
      How many transects?
      How often did you repeat the process?
      Did you account for seasonal and other factors?
      What sort of statistical analysis did you conduct of your data?
      Where were the results published?
      Can we see them please?

      "...What does that make you then?..."

      It doesn't 'make' me anything Jim. But your constant trolling and lies about science makes you a denier.

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    7. Jim Inglis

      retired

      In reply to Mike Swinbourne

      "Hate to break this to you Jim, but 'getting a list' from the ranger and walking around is not a scientific study. Unless you can tell me a few things"

      Whether or not I confide in a non-performer like you Mike, I doubt would make the difference between it being science or not.

      You don't get that doing this over a period of ~ 40 years gives someone a bit of an insight into what's going on there.

      You have NEVER done it but you are sure that I have done it wrong.

      Not only the denial of science but the hubris is breath taking.

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    8. Julie Fechner

      Retired (Grumpy old woman)

      In reply to Jim Inglis

      Jim, more unscientific emotion. The dingo is not feral, and does not as you say 'wipe out' native wildlife. I suggest you access any reputable scientific data base and you will find an ever growing body of evidence (some conducted by Prof Chris Johnson one of the writers of this article) that demonstrates the role the dingo plays in protecting our small endangered native taxon by both eliminating and changing the behavior of foxes and cats. Without the dingo it is likely we will lose another 20 Critical Weight Marsupials.

      Science is not misled, science is a process that collects, analyses and reviews evidence.

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    9. Julie Fechner

      Retired (Grumpy old woman)

      In reply to Henry Verberne

      Henry, I and others have been asking Jim for evidence for a long time, but I think he fails to understand the basic concept of the scientific process. His arguments are very short on fact and high on emotion and wild speculation.

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    10. Julie Fechner

      Retired (Grumpy old woman)

      In reply to Jim Inglis

      Jim, you seem to be a frequent visitor to Fraser Island. I suggest you ask the Rangers why no studies have been conducted.

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    11. Julie Fechner

      Retired (Grumpy old woman)

      In reply to Jim Inglis

      Jim, you still do not GET IT. Just because you walk over Fraser Island and you observe, that is NOT science. If you understood science you would have understood the comments of Mike above. Your continued emotional rantings demonstrate how little you actually understand about the Australian ecosystem, and the crucial role the dingo plays in our ecosystem. I suspect that Mike knows a lot about science.

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    12. James Hammond

      Ecologist

      In reply to Jim Inglis

      "All this when our native wildlife are in serious decline and being wiped out, not only by the dingo, but all the other more apex predators that have arrived since."

      Jim, you do yourself no favours by using terms like 'more apex'. A fully grown dingo (especially in a pack) can kill and consume the fox and the cat. The reverse is not true. Therefore, the Dingo is THE apex predator in the terrestrial Australian environment.

      You can argue all day about whether 4000 + years of occurence on mainland Australia makes the Dingo a native species. However, the evidence suggests that the Dingo has an important role to plan in mesopredator (fox and cat) and large herbivore (i.e. kangaroo) control, for the betterment of critical weight range natives. We would be wise to utilise the options that we currently have available. If we wipe out the Dingo, what will control large herbivores? Certainly not humans, with the uneconomic prospect of killing and selling all that marsupial meat.

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    13. Scott Morris

      logged in via Facebook

      In reply to Jim Inglis

      To propose that the dingo caused the extinction of the Thylacine on mainland Australia is not correct - http://www.australiangeographic.com.au/news/2013/09/dingoes-cleared-of-mainland-extinctions/.

      Consider the condition of the bulk of Australia - arid lands and desert. Consider the bulk of Tasmania - temperate rainforest, high rainfall, large rich native grasslands. Consider the variation in indigenous land management between the mainland and Tasmania.

      Now, add in the published scientific…

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    14. Jim Inglis

      retired

      In reply to Julie Fechner

      Julie, please stop ranting about how convinced you are about the dingo's capacity to be the guardian angel of our endangered native wildlife. If you want to prove how beneficial it is just go to FI and see for yourself.

      Even your friend Mike would probably be able to notice how it's wiping out the natives [if he got his transects right, that is]

      Then you could go to Tasmania where it has never been and compare the two.

      Why have you, Mike and science never done the bleedin' obvious I wonder?

      Never occurred to you, maybe?

      But you both still haven't answered my very simple question:

      How do we control our many feral predators if the dingo is protected in our wildlife reserves?

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    15. Jim Inglis

      retired

      In reply to James Hammond

      James, in the real world [not some fenced, treeless sandhills where the prey is introduced into terrain not of their choosing] the cats and foxes are not bothered by the dingo, or dogs either.

      And dogs, not dingoes, are the current apex predator.

      Please consider and answer the question I asked above.

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    16. Mike Swinbourne

      logged in via Facebook

      In reply to Jim Inglis

      "....Why have you, Mike and science never done the bleedin' obvious I wonder?...Never occurred to you, maybe?...."

      Yeah Jim. Scientists are stupid people, and the 'bleedin obvious' never occurs to them. Lucky we have retired landscape gardeners who are prepared to share tales from their holiday - trekking over the wilds of Fraser Island with a brochure in their hand. rescuing wallabies from being eaten by predators - aren't we?

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    17. Jim Inglis

      retired

      In reply to Scott Morris

      "Conclusion: The dingo did not cause the extinction of the Thylacine,"

      That's just a possibility, NOT a conclusion. It was well accepted by observers in those days when the Thylacine was still alive that a canid predator was a lot smarter than a marsupial predator.

      So the dingo certainly would have contributed to the extinction and to think otherwise is self delusion.

      Marsupial prey evolved during the last 50 million years with less intelligent marsupial predators and now, when many species…

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    18. Jim Inglis

      retired

      In reply to Mike Swinbourne

      "Yeah Jim. Scientists are stupid people, and the 'bleedin obvious' never occurs to them."

      Stick around Mike.

      You'll learn something yet.

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    19. Scott Morris

      logged in via Facebook

      In reply to Jim Inglis

      The comments made by early European settlers with respect to Thylacine Vs Dog interactions were that the Thylacine was "cowardly" (refer "Thylacine: Tragic Tale of the Tasmanian Tiger" for numerous references) and retreated in fear of both man and dog. The recorded observations of the persecutors were that dogs were often successful WHEN AIDED BY MAN in capturing and killing Thylacines. To use a suggestion that the dingo was "smarter" than the Thylacine and therefore singularly responsible for it's…

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    20. Jim Inglis

      retired

      In reply to Scott Morris

      Scott, you are trying to reduce a scientific discussion down to one of cheering for one side or the other.

      As well as that, you refuse to understand that I have no objections whatsoever to native apex predators as opposed to feral ones.

      Please try to be rational.

      Please see my response to Ernest Healy:

      "Ernest, anyone who thinks they can state with any certainty that native wildlife on the whole of the continent of Australia benefits from having a pack of feral dogs as a protected apex…

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    21. Scott Morris

      logged in via Facebook

      In reply to Jim Inglis

      "Scott, you are trying to reduce a scientific discussion down to one of cheering for one side or the other."
      No, Jim, i am presenting rational counter arguments in response to your rhetoric. I understand your confusion as it seems you are unaccustomed to having to support your claims, undertake research or provide facts when contributing to a discussion. To be clear, a fact is: "a thing that is known or proved to be true."

      In the format of a scientific discussion, this requires supporting experimental…

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    22. Scott Morris

      logged in via Facebook

      In reply to Jim Inglis

      My concluding statements are a proposition for consideration of the 'logic' you are applying to management of the dingo. My reasoning and logic is that, if i apply the theories and logic you seem t apply and state, Jim, that i would have to extend my observations to other species.

      This is not "cheering" for one side or the other, this is a rationalisation of those opinions by ruling them out to other species. If they apply to one species, they must apply to others to be logical?

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    23. Julie Fechner

      Retired (Grumpy old woman)

      In reply to Jim Inglis

      Jim, I am not ranting I have provided you with a number of excellent scientific papers; have you been able to access them and read them, or did you just dismiss them unread. I have just presumed you have access to scientific data bases; do you?

      Your comments about transects further tells me and other readers of your posts just how ignorant you are in terms of understanding any form of science. Transects, and using transects are a powerful tool in ecological scientific research, but you appear to make fun of the concept and that demonstrates to me, and others how devoid you are of any ability to make creditable scientific observations, analyze the results and have them published in the scientific literature..

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    24. Julie Fechner

      Retired (Grumpy old woman)

      In reply to Scott Morris

      Well said Scott. Jim fails to demonstrate any logic, and has totally dismissed a number of excellent scientific papers as irrelevant. I am not sure that he has even read them, as he has not made one comment demonstrating that he has.

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  4. James Hill

    Industrial Designer

    One might imagine that the survivors of the ten thousand year drought which ended five thousand years ago might have changed their behaviour in response as alluded to in the article.
    Why is the study "Riverine Response to Altered Hydrologic Regimen" never referenced in all these casual climate articles?
    Casual in that the first peoples are accused of causing climate change without the least evidence ever being produced or even thought to be necessary.
    You know, an excedingly small and widely dispersed…

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  5. Colin Samundsett

    retired BSurv

    "increasing human population size was probably having profound effects on Australian ecosystems for several thousand years before the arrival of Europeans." That fits well with the 1937 comment by Charles Fenner to Dudley Stamp: "If lands are productive, population increases, and the pressure becomes as great as ever." But --.
    There would have been some lean periods - associated with winnowing of Aboriginal numbers - during the 40,000 years until the Holocene's commencement about ten thousand…

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  6. Paul Prociv

    ex medical academic; botanical engineer

    As a relatively recent arrival, the dingo might be viewed as a hybrid native/feral, but there’s little doubt it has changed the ecology of the continent in its time – albeit nowhere to the extent that Australia’s most devastating feral, Homo sapiens, has.
    While some argue that dingoes specialise in predating on small native mammals, I find it intriguing that, in central Australia, packs of them have focused their attention onto herds of camels, following them relentlessly and skilfully picking off the weak and young. This predator-prey cycle mimics those elsewhere, such as wolf-reindeer or wolf-bison, and no doubt will lead to an evolutionary growth in the individual size of these dingoes. It also facilitates the establishment of specific parasite life-cycles. It should come as no surprise when the hydatid tapeworm, Echinococcus granulosus, becomes thoroughly established in the outback (as it was in sheep-farming districts around the country).

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  7. christopher gow

    gainfully employed

    Thank you for a very interesting article and for the links to the papers by Johnson and Williams on estimates of population growth prior to European conact.
    I recall a publication in the last few years suggesting a recent migration to Northern Australia from southern India that led to an enhanced genetic diversity in Northern Australian populations. Is it a reasonable suppostion that it was this late migration that brought wild dogs to the continent some 4,000 years ago? And further, could this…

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