Authors: Thomas M Newsome, Aaron C Greenville, Mike Letnic, Euan G Ritchie and Christopher R Dickman
Published in:Food Webs (early view)
We challenge the arguments of Morgan et al. in regard to the efficacy of dingo reintroductions Image credit: Daryll Bellingham via Flickr
In their paper “Trophic cascades and dingoes in Australia: does the Yellowstone wolf-elk- willow model apply?” Morgan et al. (2016) argue that the case for dingo reintroduction in Australia, based on trophic cascade theory, is “weak”. They conclude that, “because of climate instability, the strong top-down trophic responses reported from the Yellowstone National Park case study are unlikely to apply in arid and semi-arid south-eastern Australia and are speculative at best”.
We agree that dingoes (Canis dingo) are likely to exert different effects on ecological communities in Australia as compared to grey wolves (Canis lupus) in North America. A comparison of body sizes and dietary preferences between these canid species alludes to their functional ecological differences. Differences in the biological communities and climate between Yellowstone National Park and Australia also prevent direct comparisons of trophic cascade-processes between the two regions. These facts should not, however, preclude examination of the efficacy and consequences of dingo reintroductions in Australia.
We contend that Morgan et al. (2016):
misunderstand the circumstances that make trophic cascades important to consider in Australia,
do not acknowledge key reasons why dingo reintroduction has been proposed,
haven’t recognised the different pathways by which dingoes could influence ecosystems via trophic cascades, and
do not fully acknowledge literature and theory relevant to understanding the interplay of bottom-up and top-down processes in Australia.
Our reply is intended to assist managers and decision makers when deciding whether or not to reintroduce dingoes into Australian ecosystems.
Newsome TM, Greenville AC, Letnic M, Ritchie EG, Dickman CR (2017) The case for a dingo reintroduction in Australia remains strong: A reply to Morgan et al., 2016, Food Webs,PDFDOI
This month I attended the inaugural Threatened Species Summit held at Melbourne Zoo. I used my five minutes to be deliberately provocative; I spoke about rewilding.
Cats, rats and foxes have wrought havoc on Australian wildlife and ecosystems. Image credit Paul Hocksenar, Jude, Paul Hocksenar via Flickr.
Cats, rats and foxes have wrought havoc on Australian wildlife and ecosystems. Known as “invasive mammalian predators”, these are species that have established populations outside their native range.
Responsible for numerous extinctions across the globe, this group of species also includes American mink in Europe, stoats and ferrets in New Zealand, and mongooses on many islands.
One common solution is to kill these predators. However, research published this week in the journal Biological Conservation shows it’s much more complicated than that. Killing invasive predators often doesn’t work and is sometimes actually worse for native wildlife.
Killing for conservation
Management of the threats to biodiversity posed by invasive predators has focused on reducing their populations using lethal control. This includes poison baiting, trapping and shooting.
These programs have at times been successful at local scales and on islands. However, they are extremely costly and they often fail to stop declines of native fauna at larger scales.
Such management programs often occur with little regard for how they might interact with other threats that are impacting ecosystems. This has led to unpredictable outcomes of invasive predator control. Sometimes it doesn’t work or, worse, it results in a negative outcome for wildlife.
Key disturbances
We identified six disturbances with strong potential to increase the impacts of invasive predators: fire, grazing by large herbivores, land clearing, altered prey populations, the decline of top predators and resource subsidies from humans (such as increased food or shelter availability).
These disturbances interact with invasive predators in three main ways.
First, disturbances such as fire, grazing and land clearing result in a loss of vegetation cover, which makes prey more vulnerable to predation.
For example, small mammals in the Kimberley region of northern Western Australia experienced more predation by feral cats in an intensely burnt area, compared with patchily burnt and unburnt areas. Grazing by livestock similarly removes protective cover. Research shows that feral cats prefer to hunt in these areas because of the improved hunting success.
Second, increases in food or declines of competing top predators can allow populations of invasive predators to increase, thereby increasing their impact on native species.
For example, introduced prey species, such as rabbits in Australia, can support larger predator populations. This can lead to increased predation pressure on native species – a process termed “hyperpredation”.
The extinction of the Macquarie Island parakeet was attributed to this process. The parakeet co-existed with feral cats for more than 60 years, but declined rapidly to extinction following the introduction of rabbits to the island in 1879. Resource subsidies, such as garbage or hunters’ carcass dumps, can also support larger predator populations, leading to greater predation pressure.
Third, many of these disturbances also have a direct impact on native species, which is exacerbated by invasive predators. For example, habitat fragmentation reduces population sizes of many native species due to habitat loss. Increased predation by invasive predators can therefore make a bad situation much worse.
Getting it right
Our synthesis shows that management of invasive predators is likely to benefit from employing more integrated approaches.
Maintaining habitat complexity and refuges for prey species is one way that invasive predator impacts can be reduced. This includes improved management of fire and grazing. Lower-intensity fires that retain patchiness could reduce the predation-related impacts of fire on native species. Such approaches may be the best option where no effective predator control method exists, such as for cats in northern Australia.
Native top predators such as wolves in Europe and North America or dingoes in Australia can have suppressive effects on invasive predators. “Rewilding” is an option in some places where these species have declined. Where native predators conflict with livestock producers, guardian animals can often protect livestock from predation instead of lethal control.
If lethal control is used, it should be applied with caution. Selectively removing individual pest species from ecosystems can do more harm than good. Multi-species approaches are the best way to avoid such surprises and the order in which species are removed is an important consideration.
Rather than focusing on single processes, conservation managers should consider the multiple disturbances operating in stressed ecosystems and use management actions that address these threats in unison. Such integrated approaches are essential if further extinctions are to be avoided.
Interactions within Mallee ecosystem food chains are out of balance.
The apex predator of the Mallee landscape — the dingo — is on the decline, allowing invasive species in the middle order of the food chain to become overabundant.
Propping up dingo numbers in the region will help control local pest species and problems associated with planned burning.
The war between cat-lovers and bird-lovers may have found its compromise: larger predators. Dingoes may do a far better job than humans of keeping feral cats in check, and without the ethical baggage. In other words, if you want to kill a feral cat, get a wild dog.
That’s the message from Arian Wallech et al. in a recently published piece: Novel trophic cascades: apex predators enable coexistence. Wallach’s paper reinforces my research into the interactions between dingoes and feral cats in Australia. Using native predators to kill or scare off introduced predators could be our best bet; working with nature , not against it.
But can we apply our learnings to other contexts and ecosystems? Stan Gehrt of Ohio State University thinks so: he studies the much-maligned coyote — specifically a thriving urban population in Chicago — which seems to be keeping the local cats at bay.
Authors: Naomi E Davis, David M Forsyth, Barbara Triggs, Charlie Pascoe, Joe Benshemesh, Alan Robley, Jenny Lawrence, Euan G Ritchie, Dale G Nimmo and Lindy F Lumsden.
Abstract
Dingoes/wild dogs (Canis dingo/familiaris) and red foxes (Vulpes vulpes) are widespread carnivores in southern Australia and are controlled to reduce predation on domestic livestock and native fauna.
We used the occurrence of food items in 5875 dingo/wild dog scats and 11,569 fox scats to evaluate interspecific and geographic differences in the diets of these species within nine regions of Victoria, south-eastern Australia.
The nine regions encompass a wide variety of ecosystems. Diet overlap between dingoes/wild dogs and foxes varied among regions, from low to near complete overlap. The diet of foxes was broader than dingoes/wild dogs in all but three regions, with the former usually containing more insects, reptiles and plant material. By contrast, dingoes/wild dogs more regularly consumed larger mammals, supporting the hypothesis that niche partitioning occurs on the basis of mammalian prey size.
The key mammalian food items for dingoes/wild dogs across all regions were black wallaby (Wallabia bicolor), brushtail possum species (Trichosurus spp.), common wombat (Vombatus ursinus), sambar deer (Rusa unicolor), cattle (Bos taurus) and European rabbit (Oryctolagus cuniculus). The key mammalian food items for foxes across all regions were European rabbit, sheep (Ovis aries) and house mouse (Mus musculus).
Foxes consumed 6.1 times the number of individuals of threatened Critical Weight Range native mammal species than did dingoes/wild dogs. The occurrence of intraguild predation was asymmetrical; dingoes/wild dogs consumed greater biomass of the smaller fox.
The substantial geographic variation in diet indicates that dingoes/wild dogs and foxes alter their diet in accordance with changing food availability.
We provide checklists of taxa recorded in the diets of dingoes/wild dogs and foxes as a resource for managers and researchers wishing to understand the potential impacts of policy and management decisions on dingoes/wild dogs, foxes and the food resources they interact with.
Davis NE, Forsyth DM, Triggs B, Pascoe C, Benshemesh J, Davis NE, Forsyth DM, Triggs B, Pascoe C, Benshemesh J, Robley A, Lawrence J, Nimmo DG, Ritchie EG, Lumsden LF (2015) Interspecific and Geographic Variation in the Diets of Sympatric Carnivores: Dingoes/Wild Dogs and Red Foxes in South-Eastern Australia. PLoS ONE 10(3): e0120975.PDFDOI
Authors: Thomas M Newsome, Guy-Anthony Ballard, Mathew S Crowther, Justin A Dellinger, Peter J S Fleming, Alistair S Glen, Aaron C Greenville, Chris N Johnson, Mike Letnic, Katherine E Moseby, Dale G Nimmo, Michael Paul Nelson, John L Read, William J Ripple, Euan G Ritchie, Carolyn R Shores, Arian D Wallach, Aaron J Wirsing and Christopher R Dickman.
Abstract
There is global interest in restoring populations of apex predators, both to conserve them and to harness their ecological services.
In Australia, reintroduction of dingoes (Canis dingo) has been proposed to help restore degraded rangelands. This proposal is based on theories and the results of studies suggesting that dingoes can suppress populations of prey (especially medium- and large-sized herbivores) and invasive predators such as red foxes (Vulpes vulpes) and feral cats (Felis catus) that prey on threatened native species. However, the idea of dingo reintroduction has met opposition, especially from scientists who query the dingo’s positive effects for some species or in some environments.
Here, we ask ‘what is a feasible experimental design for assessing the role of dingoes in ecological restoration?’ We outline and propose a dingo reintroduction experiment — one that draws upon the existing dingo-proof fence—and identify an area suitable for this (Sturt National Park, western New South Wales).
Although challenging, this initiative would test whether dingoes can help restore Australia’s rangeland biodiversity, and potentially provide proof-of-concept for apex predator reintroductions globally.
Newsome TM, Ballard G, Crowther MS, Glen AS, Dellinger JA, Fleming PJS, Greenville AC, Johnson CN, Letnic M, Moseby KE, Nimmo DG, Nelson MP, Read JL, Ripple WJ, Ritchie EG, Shores CR, Wallach AD, Wirsing AJ, Dickman CR (2015) Resolving the value of the dingo in ecological restoration, Restoration EcologyPDFDOI
The south-west of WA is a global biodiversity hotspot. The state barrier fence has had a questionable impact on controlling pest species and extending it would likely cause more harm than good.
Authors: David Forsyth, Andrew Woolnough, Dale Nimmo, Euan Ritchie, Malcolm Kennedy, Anthony Pople and Ian Watson
Published in: Australian Veterinary Journal, volume 92, number 12 (December 2014)
Allen and West recently proposed that dingoes (Canis dingo, including hybrids with feral dogs C. lupus familiaris) are a critical causal factor in the decline of Australia’s sheep (Ovis aries) flock and implied that dingoes would cause the rangeland sheep industry to disappear within 30−40 years.
We agree that dingo predation can reduce the profitability of affected sheep properties and has important negative social effect on rural communities, and that exclusion fences and a range of lethal control methods are options for reducing those negative effects.
However, we argue that the importance of dingoes as a cause of the decline in Australia’s sheep flock has been overstated.
Forsyth D, Woolnough AP, Nimmo D, Ritchie EG, Kennedy M, Pople A, Watson I (2014) A comment on the influence of dingoes on the Australian sheep flock. Australian Veterinary Journal, 92: 461–462. PDFDOI
Feral cats are devastating our wildlife, so we need a long-term, sustainable solution. This is where Australia’s natural predators come in.
Feral cats are decimating Australian wildlife. Could the introduction of apex predators be part of the solution? Image credit Timo via Flickr.
A few moments on the internet will reveal that, as companion animals, cats are rivalled only by dogs. Our love affair with them is hardly surprising: they are elegant, graceful and affectionate animals. But they are also highly adaptable and successful hunters. Sadly our soft spot for them brings with it disastrous consequences for smaller wildlife species, particularly mammals, birds and reptiles.
Cats are wreaking havoc on our native wildlife, from northern Australia’s Kimberley to southern Australia’s Alps: nowhere is unaffected. Along with other threats such as habitat loss and fire, cats are pushing many native animals to the brink of extinction.
How serious is the cat problem? It’s been estimated that there may be as many as 15 million feral cats in Australia, each killing about five native animals per night: a nightly total of around 75 million native animals. And it’s not just feral cats doing the damage; that adorable Fluffy has a sinister side too. It often isn’t recognised that there is abundant and diverse native wildlife in and around many Australian cities and towns, including bandicoots, sugar gliders, quolls, koalas, parrots, water dragons and snakes. The development of remotely triggered camera traps has provided ample evidence that such wildlife frequently falls victim to domestic cats on their nightly excursions.
For a long time our other invasive predator of note, the European red fox, was seen as enemy number one to our wildlife, particularly mammals, but there’s a growing realisation that its many meals are eclipsed by those of cats, both feral and owned. Globally, cats are rated at 38th and red foxes at 99th on the IUCN’s list of 100 of the World’s Worst Invasive Alien Species.
And it’s not just cats’ appetites that are doing the damage. Cats are the primary host of the parasite Toxoplasma gondii, which can infect most mammals and birds, causing the potentially fatal disease toxoplasmosis (toxo). Even when not lethal, toxo can impact wildlife populations indirectly, through effects that include impaired vision, disorientation, loss of coordination, anorexia, lethargy, fever, skewed offspring sex ratios and abortion. Most bizarrely, animals infected with toxo are often attracted to the smell of cats and hence are more likely to be killed and eaten by them; a kind of parasite-driven mind control.
So what can we do to reduce the damage done by cats and mitigate this national conservation disaster? The most urgent needs are for vigorous education and awareness campaigns about the impacts of cats on wildlife, and tighter regulations and enforcement around responsible cat ownership. This should include mandatory desexing, the imposition of night-time curfews and containment of cats within pet owners’ properties at all times.
In addition, a number of on-ground solutions are already available or under consideration; there is no doubt that a range of measures will be essential. These include the development of cat-specific poison baits and release of a cat-specific virus. However cat control through disease and poison programs are unlikely to be effective long-term, as natural selection will favour disease-resistant and cautious cats which will result in rapid population bounce-back. After all, cats are known for their smarts, being more attracted to moving prey and suspicious of foreign objects. Under good conditions, furthermore, they can reproducequickly and bountifully.
Fencing can effectively exclude cats from habitats and provide wildlife refuges, and they play a critical role in holding the line for species such as bilbies, already teetering on the edge of extinction. However the use of fencing as a regular and ongoing strategy for wildlife conservation in our vast country will not only be logistically challenging (perhaps impossible) but also forbiddingly expensive. More fences will also result in it becoming harder and harder to see bilbies, bandicoots and many other native species in the wild. What a sad outcome for our nation and what an indictment of our allowing cats to reign supreme and unchecked!
Cue the predator
Why are cats able to run rampant? A significant reason is the lack of balance that now characterises our ecosystems. A crucial step is likely to be returning native top predators, in particular dingoes and Tasmanian devils, to landscapes, so that they can resume their important ecological roles. Scientific research (pdf) is strongly suggesting that dingoes not only kill cats but also instill fear in them, which means that they avoid areas and times where dingoes are active. Hence dingoes can provide a 24-hour-a-day, seven-day-a-week, cat control service.
If we want to conserve our iconic and globally unique wildlife then we need to work with, rather than against nature, and supporting more positive management of dingoes and returning Tasmanian devils to mainland Australia for their biodiversity benefits (pdf)would be one of the best and most cost effective things policy-makers could do now. Non-government conservation organisations such as the Australian Wildlife Conservancy are already leading the way.
In 1995 the USA and Canada worked together to reintroduce wolves to Yellowstone for their ecosystem benefits. The success of this bold step is now the stuff of legend. Isn’t it time we had our ‘Yellowstone moment’ and began restoring Australia’s ecosystems to some of their former glory?
Authors: Keith Bradby, James A Fitzsimons, Andrew Del Marco, Don A Driscoll, Euan G Ritchie, Jenny Lau, Corey JA Bradshaw and Richard J Hobbs.
Published in:Ecological management and restoration
Abstract
Western Australia’s State Barrier Fence represents a continuation of colonial era attitudes that considered kangaroos, emus and dingoes as vermin.
Recent plans to upgrade and extend the Barrier Fence have shown little regard for ecological impacts or statutory environmental assessment processes.
Emus are known to travel up to 1000 kilometres between seasons. This is what happens when their migration is impeded by the West Australian State Barrier Fence. Image credit : Graeme Chapman.
Bradby K, Fitzsimons JA, Del Marco A, Driscoll DA, Ritchie EG, Lau J, Bradshaw CJA Hobbs RJ (2014) Ecological connectivity or Barrier Fence? Critical choices on the agricultural margins of Western Australia. Ecological management and restorationPDFDOI
Parts of Australia are teeming with over-abundant herbivores, such as feral goats and native kangaroos. But is shooting the best approach? Or can a well-managed dingo population lead to a well-managed kangaroo population?
Australia’s ‘native dog’ has a bad reputation, with farmers long having problems with their attacks on livestock. But some farmers are now finding a dingo-friendly approach is gaining better results.
Farmers, conservationists and ecologists re-think Australia’s approach to dingoes on Channel Ten’s The Project.
In this 3-minute feature story on Channel Ten’s The Project, I add my voice to the dingo debate; how culling and baiting have been unsuccessful strategies, and why maintaining apex predators adds balance to our ecosystems.
Authors: Christopher N Johnson, Mathew S Crowther, Chris R Dickman, Michael I Letnic, Thomas M Newsome, Dale G Nimmo, Euan G Ritchie and Arian D Wallach.
Abstract
There has been much recent debate in Australia over whether lethal control of dingoes incurs environmental costs, particularly by allowing increase of populations of mesopredators such as red foxes and feral cats.
Allen et al. (2013) claim to show in their recent study that suppression of dingo activity by poison baiting does not lead to mesopredator release, because mesopredators are also suppressed by poisoning.
We show that this claim is not supported by the data and analysis reported in Allen et al.’s paper.
The management of dingoes is a highly conflicted and frequently emotional issue in rural Australia. Image by Peripitus [CC-BY-SA-3.0] via Wikimedia Commons. Skull and Crossbones icon by Jens Tärning [CC-BY-SA-2.0] via the Noun Project.Johnson CN, Crowther MS, Dickman CR, Letnic MI, Newsome TM, Nimmo DG, Ritchie EG, Wallach AD (2014) Experiments in no-impact control of dingoes: comment on Allen et al. 2013. Frontiers in Zoology 11:17 PDFDOI
It’s a big night for ‘Team Dingo’ at the Eureka Prizes.
Our research centres on the much-maligned and often polarising predator: the dingo.
Though sometimes miscast as vermin, our research shows that dingoes are key elements in the struggle to reduce damage caused by foxes, feral cats and even kanagroos; and that ecosystems with dingoes have better vegetation and more diverse and abundant populations of small native mammals. In fact, a good dose of our native dog can sustain biodiversity and help land managers control invasive species.
Part cultural icon, part livestock pest, Australia’s largest terrestrial predator is also an important component of healthy ecosystems and a useful contributor to environmental recovery and the protection of threatened species.
‘Team Dingo’ is:
Professor Chris Johnson, University of Tasmania
Dr Michael Letnic, University of New South Wales
Dr Euan Ritchie, Deakin University
Dr Arian Wallach, James Cook University
Adam O’Neill, Evelyn Downs Station.
‘Team Dingo’ celebrate at the Eureka Prizes. Left to right: Dr Euan Ritchie, Dr Arian Wallach, Prof Chris Johnson, Dr Mike Letnic. Image: Australia Museum and Daniel O’Doherty.
On behalf of the team, I would also like to congratulate our fellow Eureka finalists: Dr David Post, Dr Francis Chiew (CSIRO), Dr Bertrand Timbal and Dr Harry Hendon (Bureau of Meteorology) for their work on the causes and predictability of climate variability and its impacts on water availability; and Dr Jason Sharples (University of New South Wales) and Richard McRae (ACT Emergency Services Agency) for their research on the causes and effects of catastrophic firestorms.
Presented annually by the Australian Museum, the Eureka Prizes reward excellence in the fields of research and innovation, leadership and commercialisation, school science and science journalism and communication.
Another attack on Fraser Island — the flashpoint for dingo management issues — has highlighted our complex relationship with Australia’s largest terrestrial predator.
The Fraser Island Dingo is in the news for all the wrong reasons. Image by Glen Fergus [CC-BY-SA-2.5], via Wikimedia CommonsWhen wolves were reintroduced into Yellowstone National Park in 1995 park after a near 90-year absence, the balance of an entire ecosystem shifted. Grazing by overabundant elk dropped leading to recovery of native aspen, willow and cottonwood trees. Beavers returned, small predators and scavengers increased and coyote numbers dropped, indirectly benefiting the threatened pronghorn antelope.
Recent research from around the globe is demonstrating that large predators, like wolves and dingoes, play a critical role in maintaining healthy ecosystems.
Several authors have recently argued that dingoes could be used to help conserve biodiversity in Australia. Fleming et al. (2012) [Australian Mammalogy 34, 119–131] offer the alternative view that restoration of dingo predation is unlikely to help native species, and is more likely to do harm. We think many of the arguments used by Fleming et al. to reach that conclusion are either unsound or beside the point, and we explain why.
The dingo is Australia’s largest terrestrial predator. But what does that mean for smaller predators, prey and the interactions between them? Image by By Christopher Watson [CC-BY-SA-3.0] via Wikimedia Commons. Johnson CN, Ritchie EG (2013) The dingo and biodiversity conservation: response to Fleming et al.Australian Mammalogy, 2013, 35, 8–14DOIPDF
![The Fraser Island Dingo is in the news for all the wrong reasons. Image by Glen Fergus [CC-BY-SA-2.5], via Wikimedia Commons](http://upload.wikimedia.org/wikipedia/commons/4/4c/Dingo_Fraser_Is.jpg)
Applied ecology and conservation research group 