The dingo fence from space: satellite images show how these top predators alter the desert

The dingo fence in the Strzelecki Desert.
Mike Letnic

Adrian G. Fisher, UNSW; Charlotte Mills, UNSW; Mike Letnic, UNSW; Mitchell Lyons, and Will Cornwell, UNSW

As one of the longest structures in the world, the dingo fence is an icon of Australia. It stretches more than 5,600 kilometres across three states, including 150 kilometres that traverses the red sand dunes of the Strzelecki Desert.

Since it was established in the early 20th century, the fence has had one job: to keep dingoes out. The effect of this on the environment has been enormous — in fact, you can see it from outer space.

Our research has, for the first time, used satellite imagery to show the effects of predators on vegetation at a vast scale.

Dingoes eat kangaroos, and kangaroos eat grass. So on the side of the fence where dingoes are rare, there are more kangaroos, and less grass cover between sand dunes. This has important flow-on effects for the ecosystem in the region.

Similar changes to vegetation may have occurred throughout the world, where other large predators, such as wolves or big cats, have been removed. But these aren’t visible without the stark contrast boundaries like the dingo fence provide.

Reshaping the landscape

The fence was built to stop dingoes moving into sheep grazing land in southeastern Australia. As Australia’s largest terrestrial predator, dingoes pose a big threat to livestock.

Today, dingoes “inside” the fence continue to be killed by various means (not all of them humane), including poison baits, trapping and shooting.

Where dingoes are removed, increasing populations of kangaroos can lead to overgrazing.
Nick Chu

It has long been understood that removing large predators can drive changes in ecosystems across large areas. A well-known example is the removal of wolves in Yellowstone National Park in the 1920s, which saw an elk grazing increase, limiting the growth of tree and shrub seedlings.

Where dingoes are removed, increasing populations of kangaroos can lead to overgrazing. This, in turn, damages the quality of the soil, making the landscape more vulnerable to erosion.

Less vegetation can also leave small animals, such as the vulnerable dusky hopping mouse, exposed to other threats like cat predation. Indeed, 2019 research showed dingoes “outside” the fence keep cat and fox populations down in the Strzelecki Desert.

And research from 2018 showed dingo removal could even reshape the desert landscape, as changes to vegetation alter wind flow and sand movement.

Changes this large can’t be seen from the ground

Often, however, the effects of removing predators have gone unnoticed. There are two main reasons why.

First, many large predators were removed before scientists monitored ecosystems. For example, wolves were hunted to extinction in Britain during the 17th or 18th century (although there are now proposals to reintroduce them).

Second, changes occur over such large areas, so it’s difficult to spot any differences when researching from the ground.

So to gauge the impact of the fence, we used images captured by sensors on the NASA Landsat satellites, which have been regularly observing the Earth since 1972.

We looked at a section of the fence that follows the state border of New South Wales through the Strzelecki Desert, and used this to analyse the effects of removing a top predator.

32-year time lapse of dead vegetation cover for the Strzelecki Desert.

Capturing the impact

We used images processed for Australia by the Joint Remote Sensing Research Program, which are publicly available.

Using thousands of field measurements, each satellite image was converted into an image of “fractional cover”. This splits the landscape into three core components: bare soil, green vegetation and dead or dry vegetation.

The dead vegetation fraction, which includes all non-photosynthetic material such as dry leaves and twigs, is particularly useful in the desert. It’s a more reliable indicator of vegetation cover, as green vegetation only sticks around for three months or so after rain.

Viewing “natural colour” satellite images of the Strzelecki Desert, as our eyes see the world, doesn’t show the differences across the dingo fence very well. But when we view images of dead vegetation cover a few months after rainfall, we can see the stark effect kangaroo grazing has on the landscape, where dingoes are rare.

You can see these effects in the images below.

A natural colour Landsat image from winter in 2011 after a large rainfall event (left) does not show the dingo fence, though it does when converted to dead vegetation cover (right).
Adrian Fisher

When we analysed dead vegetation cover images for each season between 1988 and 2020, we found obvious differences between the maximum dead vegetation cover and the variability of dead vegetation cover through time, as the images below show.

The differences in vegetation cover across the dingo fence become most apparent after satellite images are converted to dead vegetation cover and analysed over time.
Adrian Fisher

The results from satellite images were supported by ground surveys. This included repeated nighttime counts of kangaroos and dingoes seen with powerful spotlights.

We also fenced off plots and observed how the vegetation changed. After five years, the kangaroo-free plots in the dingo-free areas looked like islands of grass in an otherwise bare desert.

One of the fenced plots excluding kangaroos in Sturt National Park, western NSW, showing a clear difference in vegetation cover due to grazing pressure where dingoes are rare.
Mike Letnic

What do we do about dingoes?

So, should we tear down the fence to reintroduce dingoes back into landscapes for the biodiversity benefits, like wolves in Yellowstone?

There are no simple answers to this question. Allowing dingoes to return to the landscape inside the fence will reduce kangaroo numbers and increase grass growth — but will also devastate sheep farming.

Conservationists, farmers and other land managers need to start discussing where and how we can safely return dingoes to landscapes, finding a balance between restoring ecosystems and protecting farms.

Adrian G. Fisher, Lecturer in Remote Sensing, UNSW; Charlotte Mills, Visiting Fellow, UNSW; Mike Letnic, Professor, Evolution and Ecology Research Centre, UNSW; Mitchell Lyons, Postdoctoral research fellow, UNSW, and Will Cornwell, Associate Professor in Ecology and Evolution, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Dingoes

Air-dropping poisoned meat to kill bush predators hasn’t worked in the past, and it’s unlikely to help now

Justine M. Philip, Museums Victoria

After the summer’s devastating bushfires, the New South Wales government announced a plan to airdrop one million poisoned baits in the state’s most vulnerable regions over the next year. The plan is aimed at protecting surviving native animals from foxes, feral cats and wild dogs.

This isn’t the first time aerial baiting has been used in NSW recently. As the fire season got underway in September last year, the government’s biannual aerial baiting program scattered baits over nearly 8 million hectares in the Western Division alone – dispensing 43,442 aerial baits and 115,162 ground-laid baits over the drought-stricken region.

Biosecurity officers drying meat baits for the Autumn baiting program in Broken Hill last year.
NSW Government, Local Land Services, Western Region

In a study published this week, I explore Australia’s history as pioneers of this technology. The review raises serious concerns about the ethics and poor results of baiting programs, and the high uptake of baits by non-target species such as marsupials.

D-day for dingoes

Aerial baiting has been Australia’s foremost weapon against pest species for the past 74 years. The initial target was the dingo, to protect unguarded livestock from being killed.

It started on Remembrance Day in 1946. Around 367,000 dry meat baits were airdropped across Queensland, each containing enough strychnine to kill an adult dingo. The campaign was considered a victory, despite only recovering one dingo carcass during the initial operation. Livestock predation apparently decreased; tracks in the sand vanished.

The following year, 1.5 million baits were distributed. Then in 1948 the quantity increased to 2.5 million baits across remote regions of Queensland and the Northern Territory.

Livestock predation decreased after airdropping baits, but at what cost?
CSIRO Science Image, CC BY

Thousands of baits to kill one dingo

The strychnine tablets took up to 12 tortuous hours for the poison to deliver its lethal kill. The baits used in research trials were still toxic after 14 weeks.

There was huge public criticism of the project at the time – much of it from graziers. They claimed ants and valuable pest-eating birds – magpies, small hawks, butcher birds, crows, ibis and curlew – were eating the baits.

In response, the Queensland government set up the first monitored trials. The 1954 report from the Chief Vermin Control Officer recorded:

In the dry season campaigns, the baits are dropped on water-holes, soaks, junctions of dried water courses, gorges in hills and all places where dogs must travel or gather in their search for water and game and in their movements with pups from the breeding areas.

The data recorded an average 14,941 baits dispensed for every dingo carcass recovered. Anecdotal evidence suggests the program was considered a success.

CSIRO research worker with young dingo, 1970.
National Archives of Australia

Then in 1968 – 21 years after aerial campaigns began – a four-year CSIRO study tested the effectiveness of aerial baiting. It found the 1954 report was far from conclusive – the dingoes may just have moved elsewhere. And it concluded: “clearly aerial baiting was not effective”.

But there was an important caveat:

It is important to emphasise that, though this aerial baiting campaign was a failure, such a conclusion does not necessarily apply to any other campaign.

On the strength of that, aerial baiting programs continued.

Not much has changed

Despite millions of baits applied annually to the environment since the 1940s, Australia’s biodiversity has plummeted.

What’s more, developments in the technology haven’t come far. Raw meat baits eventually replaced dry baits in some areas. Strychnine was superseded by 1080, a less harmful poison to non-target native species, and less persistent in the environment.

Trials in the 1980s brought the bait-to-kill rate down to 750 to 1 (baits per dingo carcass recovered). This was considered a cost-effective and successful outcome.

Soon after, aerial baiting found a new market, becoming the frontline defence against Australia’s plummeting biodiversity from invasive predators.

Baits are not benign to marsupials

In 2008, the Australian Pesticides and Veterinary Medicines Authority imposed a limit of ten baits per kilometre to reduce risk to non-target species.

Pest control agencies need four times that amount of poison to achieve a successful kill rate. Yet planes have been dispensing baits at this lower and ineffective rate since 2008.

Why? It seems a balance between wildlife safety and effective canine or predator eradication isn’t possible with this technology.

In fact, it has been impossible to accurately trace the fate of baits thrown from aeroplanes into remote terrain. Even ground baiting trials have proved difficult to monitor. A 2018 trial found non-target species consumed more than 71% of ground-laid meat baits, including ravens, crows, goannas, monitor lizards, marsupials and ants.

Four young dingoes died during this trial, representing only a 1.25% uptake by target. Despite monitoring with cameras and sand traps, 599 baits out of 961 in the trial disappeared without a trace.

These baits are not benign. Repeat doses can kill marsupials; non-lethal doses can kill pouch young. Secondary poisoning can also be lethal. Applying this outdated technology to vulnerable bushfire regions is from a historical viewpoint, potentially hazardous.

Surely there’s another way

There are new technologies available to help protect and repair Australia’s fragile and broken ecosystems. Remote surveillance, drones, AI, heat sensing equipment, and more could locate populations and dispatch dangerous animals.

If aerial baiting continues, aerial surveillance could at least follow the fate of the one million baits and tell us what and who is eating them – who lives and who dies in the stripped-bare landscape.

One thing is for certain: halting the program would prevent hundreds of thousands of these poisoned meat baits ending up in the stomachs of our treasured native animals.

Justine M. Philip, Doctor of Philosophy, Ecosystem Management, Museums Victoria

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Dingoes found in New South Wales, but we’re killing them as ‘wild dogs’

One in four of nearly 800 animals genetically tested were pure dingo.
Michelle J Photography

Kylie M Cairns, UNSW; Brad Nesbitt, University of New England; Mathew Crowther, University of Sydney; Mike Letnic, UNSW, and Shawn Laffan, UNSW

There is a widespread belief dingoes are as good as extinct in New South Wales and nearly all dog-like animals in the wild are simply wild dogs. This belief is bolstered by legislation and policies in NSW, which have removed the word dingo and refer only to “wild dogs”.

But our research, recently published in the journal Conservation Genetics, challenges this assumption. We performed DNA ancestry testing, much like the ancestry tests available to people, on 783 wild canines killed as part of pest control measures in NSW.

Roughly one in four of the animals we tested were pure dingoes, and most were genetically more than three-quarters dingo. Only 5 of the 783 animals we tested turned out to be feral domestic dogs with no dingo ancestry.

If it looks like a dingo, acts like a dingo and shares dingo genes… there’s a pretty good chance it’s a dingo.
Michelle J Photography, Author provided

Dingo hotspots

Studies carried out by the CSIRO in the 1980s and ‘90s examined the skulls of wild canines in southeastern Australia, and concluded they were largely hybrids of dingoes and dogs.

In NSW all wild dogs are classified as pest animals. Under the NSW Biosecurity Act 2015 all landholders have a duty to control wild dogs to minimise the risk of negative impacts on neighbouring land.

This policy requires all public and private landholders in NSW to display signs warning when poison baits have been laid to kill wild dogs.

But our DNA testing found three hotspots of high dingo ancestry within northeastern NSW: Washpool National Park; the coast north of Port Macquarie; and the Myall lakes region.

There were more pure dingoes in these areas. Despite these positive findings, dingo-dog hybridisation is still very prevalent in NSW. Three-quarters of wild animals carry some domestic dog ancestry.

This is not entirely surprising. Domestic pet and working dogs have lived alongside dingoes for centuries. Widespread killing of dingoes also increases the risk of hybridisation because it breaks family groups apart, giving domestic dogs the opportunity to mate with dingoes. Small populations also have a higher risk of hybridisation.

1080 poison baits are affecting dingoes as well as feral dogs.
Mike Letnic

Hybridisation is generally considered detrimental to conservation because it alters the genome. In the case of dingoes, hybridisation is a problem because hybrids may be different to dingoes and “true” dingoes will eventually disappear.

While our results show dingoes still exist and their genes are predominate, their conservation will be greatly helped if we can prevent further interbreeding with domestic dogs.

Time to resurrect the dingo

Our study has important implications for both how we describe dingoes, and the future conservation of dingoes in NSW. Most of the animals labelled as wild dogs in NSW had predominantly dingo DNA, and fewer than 1% were actually feral dogs.

The term wild dog obfuscates the identity of wild animals whose genes are mostly dingo but sometimes carry dog genes. For all intents and purposes, these animals have dingo DNA, look like dingoes and behave like dingoes, and consequently should be labelled as dingoes rather than escaped pets gone wild.

Hotspots with high dingo ancestry have significant conservation value and urgently need new management plans to ensure these pure dingo populations are protected from hybridisation. These populations could be protected by restricting the killing of dingoes in these areas and restricting access to domestic dogs on public land such as state forests.

Animals long thought to be wild dogs are actually predominantly dingoes.
Michelle J Photography, Author provided

Further ancestry testing should be conducted in more areas to determine whether there are other pockets of high dingo purity in NSW.

Undeniably, dingoes can negatively impact livestock producers, especially sheep farmers. Non-lethal strategies such as electric or exclusion fencing, and livestock guarding animals such as dogs, llamas and donkeys, may balance the need to conserve dingoes and protect vulnerable livestock.

In some circumstances, dingoes can benefit farmers because they reduce numbers of native and feral herbivores like kangaroos, feral goats, rabbits and pigs, boosting pasture growth for livestock.

If lethal control is justified, then targeted strategies such as shooting and trapping may be more suitable in high dingo conservation areas rather than landscape-wide poison aerial baiting.

It is time to resurrect the dingo. The term dingo needs to come back into official language, and we need practical strategies for limiting dingo-dog hybridisation and protecting dingo hotspots.

Kylie M Cairns, Research fellow, UNSW; Brad Nesbitt, Adjunct Research Fellow, University of New England; Mathew Crowther, Associate professor, University of Sydney; Mike Letnic, Professor, Centre for Ecosystem Science, UNSW, and Shawn Laffan, Associate professor, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Dog owners could take the lead on dingo conservation with a ‘Fido fund’

Dingo puppers. A small levy on dog costs could help create more ethical management of dingoes.
Shutterstock

Neil R Jordan, UNSW and Rob Appleby, Griffith University

Humans and dogs go way back. From wolf totems to the big bad wolf of fact and fairy tale, through sheepdogs, lap dogs, and labradoodles, our relationships with these animals are complex, emotionally charged and sometimes contradictory.

The split between humanity’s lavishing of affection on domestic dogs and our contrasting animosity towards their wild relatives is well-documented. But what of domestic dogs and dingoes?

Our research, published today, found similarly contrasting relationships in Australia, where the dingo, Australia’s native dog, is frequently killed for management. We suggest that an inexpensive “dingo conservation levy” on domestic dog costs could fund more ethical management of dingoes. In this way our affection for domestic dogs could be harnessed to improve conservation outcomes for their wild relatives.

Dingoes have an ecotourism appeal in places like K’gari (Fraser Island)
Shutterstock

Canine economics

Australians collectively spend over A$10 billion each year on their domestic dogs – housing, feeding, and sometimes even giving them the status of honorary family members. Meanwhile, government and landowners jointly spend at least A$30 million on large-scale exclusion fencing and lethal control of dingoes.

Industry funded research suggests that dingoes killing livestock, especially sheep, and efforts to control dingoes, cost at least A$145 million annually. What’s more, such losses also come with psychological stress, which you can’t always put a price on.

Other research suggests dingoes, as top predators, provide considerable economic benefits. For example, dingoes prey upon kangaroos and other herbivores that may compete with livestock for food and water. In fact, some estimates suggest dingoes improve gross margins by $0.83 per hectare in this context.

They also help biodiversity by suppressing feral cats and foxes, and dingoes have considerable ecotourism appeal in locations like K’gari (Fraser Island) and Kakadu National Park.

Managing dingoes

Australia’s current approach to dingo management highlights the paradox of an animal viewed both as a valuable native predator that should be conserved, and as a pest to be destroyed. And this makes it a nightmare to manage.

The dingo fence stretches for thousands of kilometres in the Australian outback to try to keep dingoes away from sheep and livestock.
Shutterstock

Current dingo management relies heavily on exclusion fencing and lethal control, and around 200kg of 1080 powder (poison) is administered to baits and peppered across the continent annually.

Countless bullets are also fired, and traps set, as the lion’s share of management budgets is allocated to business as usual. To break this deadly cycle, there is a clear need to provide farmers and governments with good evidence that different approaches could work. This can only be done through substantial parallel investment in robust, independent experimental tests of alternative approaches.

Despite broad support in society for non-lethal management, accessing sufficient funds to support such a transition remains challenging.

A modest dingo conservation levy could fund this. With a levy on the A$10 billion domestic dog industry, we could harness humanity’s affinity for domestic dogs to improve conservation and welfare outcomes for their wild counterparts.

It wouldn’t need to be prohibitively expensive either.

A levy on the sale of pet dogs, dog food, or both, of only about 0.3% of the amount that pet owners spend on this annually – or A$7.36 per dog – would generate A$30 million each year.

That is similar to the lowest estimates of current national spending on dingo control, which means we would potentially see the current spending doubled.

Why should dog owners pick up the tab?

Applying a levy to all dog owners may seem unfair, and perhaps it is. But as Australia’s “dingo problem” is, arguably, at least in part caused by domestic dogs gone feral, such a levy would seem no more unfair on conscientious dog owners than third-party insurance is on careful drivers.

Given that pet owners tend to view wild animals more positively and show more concern for their welfare, such a levy might actually be well received by dog-owners anyway.

An alternative approach might be to seek the voluntary involvement of pet-food manufacturers in such a scheme, giving consumers choice over whether to support it.

Dog-lovers generally also love wild animals, and may be happy to pick up the costs for ethical dingo conservation.
Shutterstock

A dingo conservation levy – perhaps supplemented by a voluntary fund for donors without dogs – might also be more acceptable and attractive if it were clear the funds would be specifically channelled towards research and uptake of non-lethal tools.

Generally, we are broadly in favour of any techniques designed to reduce the animosity towards dingoes, reduce the costs and negative impacts of living alongside them, and boost the positive effects dingoes have on ecosystems.

As some have already argued, they are all dogs at the end of the day. Perhaps then it is time that we treated them as such.

We would like to gratefully acknowledge the contributions of Mike Letnic, Henry Brink, Brad Purcell and Hugh Webster to this article.

Neil R Jordan, Lecturer, UNSW and Rob Appleby, PhD student at the Environmental Futures Research Institute, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Dingoes and humans were once friends. Separating them could be why they attack

File 20190429 194630 g4xwba.jpg?ixlib=rb 1.1 — Dingoes on K’Gari are the most genetically ‘pure’ in Australia.

Katie Woolaston, Queensland University of Technology

Two small children were hospitalised in recent weeks after being attacked by dingoes on K’gari (Fraser Island).

The latest attack involved a 14-month-old boy who was dragged from his family campervan by dingoes, an incident that could have ended with much more serious consequences than the injuries he sustained.

Fraser Island, famous for its wild dingo population, was renamed K’Gari in 2017. And the number of tourists involved in negative interactions with dingoes appears to be increasing.

The dingo, a wild dog of the Canis genus, were likely brought to Australia by Asian seafarers around 4,000 years ago.

Dingoes can be terrifying – but not when they’re puppies.
Shutterstock

While dingoes exist in many parts of Australia today, those on K’gari are thought to be “special” because of their genetic purity. This means they have not interbred with wild and domestic dogs to the same extent mainland dingoes have, and so are considered the purest bred dingoes in Australia.

They are legally protected because of this special status, and because they live in a national park and World Heritage Area. Unfortunately, it is precisely this protection and separation from humans that has driven much of the increase in interaction and aggression towards people.

This ongoing human-dingo conflict on K’Gari shows how our laws and management practices can actually increase negative encounters with wildlife when they don’t consider the history, ecology and social circumstances of the conflict area.

Law and policy ‘naturalised’ dingoes

The island’s laws and policies, such as the international World Heritage Convention and the more local Fraser Island Dingo Conservation and Risk Management Strategy, are focused on conserving a particular human idea of “natural wilderness”.

In practice, this means the management policy focuses on “naturalising” the dingo by effectively separating them from people and the sources of food they bring.

But dingoes, although wild animals, have never effectively been naturalised on K’Gari, so our attempts to maintain their “natural” and “wild” status is not entirely accurate.

K’Gari (Fraser Island) is the largest sand island in the world.
Shutterstock

Dingoes have a long history of being close with Aboriginal people. This human-dingo relationship continued as the island was used for mining and logging, as employees also lived with dingoes. They were fed by people, scavenged scraps from rubbish tips, and fed on leftover fish offal.

It is only in the last few decades we have sought to rewild dingoes by removing all forms of human-sourced food, separating them from human settlement.

Separating the animals from humans won’t work, however, when more than 400,000 tourists visit K’Gari every year, expecting to see a dingo.

International law and local management prioritise tourism, and a tourism-based economy is certainly preferable to the logging and sand-mining economies that existed before the national park was given World Heritage status in 1992.

But are such large visitor numbers in a relatively small space sustainable?

This question has been asked often, including by the Queensland government in their Great Sandy Region Management Plan.

Yet, there has been no serious consideration given to reducing tourist numbers or increasing fees, despite research suggesting visitors are willing to sacrifice some access for improved environmental outcomes and less crowding.

Such proposals have been specifically rejected by decision-makers within the Dingo Management Plan.

So where does that leave us?

We essentially have three options:

if we wish to stick with the policy of dingo naturalisation and human separation, we must change our attitudes and values towards dingoes so people maintain an appropriate distance and do not inadvertently feed them. This can happen with education, fines and collaboration. While this is essentially what policies have attempted so far, there has been little effect on overall incident numbers
we can take the naturalisation policy to its expected endpoint and completely separate tourists and dingoes. This may mean more fencing, greater fines and fewer annual visitors so rangers can educate and manage all visitors effectively
we can drastically reevaluate how we value wildlife and how we place ourselves within the natural world. This would see an enormous overhaul of the regulatory framework, and would also require a deeper understanding of all the causes of conflict, other than just the immediate issue of tourism, habituation and feeding.

In practice, an effective dingo management policy would probably require a combination of all three options to maintain the pristine state of K’Gari, conserve the dingo population and improve human safety.

Katie Woolaston, Lawyer, Queensland University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Like cats and dogs: dingoes can keep feral cats in check

File 20190403 177175 6uzk99.jpg?ixlib=rb 1.1 — Feral cats are linked to the extinction of at least 20 Australian mammals.
Shutterstock

Mike Letnic, UNSW and Ben Feit

The role of dingoes in the Australian landscape is highly debated between ecologists, conservationists and graziers. They kill livestock, but also hunt introduced animals and keep kangaroo populations in check.

Now new research sheds more light on the benefits dingoes bring to the outback. For the first time, our research clearly shows that dingoes suppress feral cat numbers.

Our research, published recently in Ecosystems, used the world’s largest fence to compare essentially identical environments with and without dingoes. Over the course of the six-year study, dingoes drove down cat numbers – and kept them down.

Feral cats are out of control

Feral cats are a serious conservation threat. They have been linked to the extinction of at least 20 mammal species in Australia and threaten the ongoing survival of more than 100 native species.

For our study, we asked whether “top-down” pressure from dingoes (through direct killing and competition for food) had a greater influence on controlling cat numbers than “bottom-up” effects (the availability of shared food sources preyed on by cats).

Dingoes drive down the population of introduced animals.
Kim/flickr, CC BY-SA

We conducted our study by comparing the numbers of dingoes, cats and their major prey species on either side of the dingo fence in the Strzelecki Desert. The fence runs along the borders of New South Wales and South Australia and was originally built to exclude dingoes from sheep grazing lands in NSW.

The state border follows the longitude line 141 east, so the fence does not demarcate any natural boundary. It simply cuts a straight line through sand dunes with similar landforms and vegetation on either side. Thus the dingo fence provides a unique opportunity to study apex predators’ effects on ecosystems: dingoes are common on the SA side, “outside” the fence, whereas on the NSW “inside” of the fence, dingoes are rare due to intensive persecution by humans.

We collected data from sites on either side of the fence in the Strzelecki Desert, at roughly four-month intervals between 2011 and 2017. Dingo and cat scat was collected at each site, to analyse and compare diets, and spotlight searches were used to record numbers of dingoes, feral cats, as well as two of their common shared food sources: rabbits and hopping mice.

Spotlight surveys revealed dingoes to be virtually absent from study areas inside the fence, with only four dingoes recorded during the study. Where dingoes were rare inside the fence, cat numbers closely followed fluctuations of their prey species consistently over the six-year span of our study. As prey numbers increased, cat numbers also increased, and similarly as prey numbers declined, cat numbers also declined.

A feral cat in outback Australia.
Shutterstock

Outside the fence, where dingoes were common, it was quite a different story. There, cat numbers were consistently lower, with numbers of both cats and dingoes following fluctuations in prey numbers across the first two years of the study. However, from 2013 onward, dingo numbers remained high and matched trends in their prey numbers for the remainder of the study.

During this time, cat numbers remained low, and by the end of 2015, cats had virtually disappeared from our study sites outside the fence and were not recorded during spotlight surveys between November 2015 and the end of our study in July 2017.

The most likely explanation for this drastic reduction in cat populations is through interference competition – either by dingoes killing some cats or by scaring others away from habitats in which they would usually hunt. Indeed, we occasionally found cat remains in dingo scats, which suggests dingoes prey on cats.

Although our scat analyses indicated that dingoes and cats eat similar foods, there was no evidence that competition for food was a major factor in how dingoes reduce cat populations. This is because prey were plentiful outside the fence, where dingoes were common and cats were rare.

This research show how dingoes can help conservation efforts by suppressing feral cat populations. It adds to previous work showing dingoes are important in maintaining healthy ecosystems, as they reduce and eradicate feral herbivores like pigs and goats, and stop kangaroos from overpopulating districts.

This article was updated on April 5 to credit Ben Feit as a co-author.

Mike Letnic, Professor, Centre for Ecosystem Science, UNSW and Ben Feit, Post-doctoral researcher

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Dingo dinners: what’s on the menu for Australia’s top predator?

Tim Doherty, Deakin University; Chris Dickman, University of Sydney; Dale Nimmo, Charles Sturt University; Euan Ritchie, Deakin University, and Thomas Newsome, University of Sydney

The dingo is Australia’s largest land-based predator, occurring across most of the mainland and on many nearshore islands.

Our new research, published in the journal Mammal Review, reveals the breadth and diversity of dingo diets across the continent.

We compiled and analysed 73 sets of data, containing details of more than 32,000 dingo droppings or stomach contents, to document the range of different species that dingoes eat, and how their diets vary between different environments.

A wide-ranging diet

We found that dingoes eat at least 229 vertebrate species. This includes 62 small mammals (less than 500 grams in mass), 79 medium-sized and larger mammals, 10 species of hoofed mammals, 50 birds and 26 reptiles. Dingoes also eat insects, crustaceans, centipedes, fish and frogs.

The true number of species is likely to be much higher because dingo diets have been poorly studied in many parts of Australia, such as Cape York Peninsula.

Large (at least 7kg) and medium-sized (0.5-6.9kg) mammals were the most common components of dingo diets, followed by small mammals, rabbits, arthropods, reptiles, birds and hoofed animals.

Average occurrence of eight food types in the diet of dingoes. Values represent the percentage of droppings/stomachs that contained each food type.

A range of introduced pest species also feature in dingo diets, including deer, goats, rabbits, hares, black rats, house mice, foxes and cats. In recent decades, the occurrence of sambar deer in dingo diets has increased as this invasive species has expanded its range.

Dingoes also eat sheep and cattle, although dietary samples are unable to distinguish between predation and scavenging, and hence tell us little about dingo impacts on livestock production. Dietary samples also do not reveal instances of dingoes killing livestock without eating them.

Regional variation

We found that what dingoes eat depends on where they live. For instance, in arid central Australia, birds, reptiles, rabbits, small mammals and insects form major parts of dingo diets. In contrast, these food groups are less important in temperate and subtropical eastern Australia, where medium-sized and large mammals such as kangaroos, bandicoots and possums are more important.

Frequency of different food groups in dingoes’ diet. Each circle represents a study and is scaled proportionally with dietary occurrence; larger circles represent a higher frequency of that food type. Top row: arthropods and small mammals (less than 500g); middle row: reptiles and medium-sized mammals (0.5-6.9kg); bottom row: rabbits and large mammals (at least 7kg).

The higher occurrence of medium-sized mammals in dingo diets in eastern Australia may be due to the lower extinction rates of native mammals there. In contrast, central Australia is a global mammal extinction hotspot, which probably accounts for the low occurrence of medium-sized mammals in dingo diets in arid and semi-arid areas.

Nonetheless, one medium-sized mammal was a major food item for dingoes in arid areas: the European rabbit. In some areas, more than 50% of dingo droppings or stomachs contained the remains of this invasive species. It is possible that native medium-sized mammals previously constituted a major part of dingo diets in arid Australia, but have since been replaced by rabbits.

Local prey availability plays a major role in determining what dingoes eat. For instance, in the Tanami Desert, reptiles were most common in dingo diets during warmer months when they are most active. However, very few studies have collected data on prey availability, partly because of the sheer number of different animals that dingoes eat.

Threatened species

Dingoes kill or eat at least 39 native species that are classed as threatened or near-threatened on the IUCN Red List. These include the northern quoll, golden bandicoot and bridled nailtail wallaby.

This tally is higher than the number of threatened species in feral cat diets (based on a previous study that used similar methods), even though cats eat almost twice as many different species overall as dingoes (400 and 229, respectively).

Today’s threatened native species co-existed with dingoes for a long time before European colonisation, which means they were able to withstand dingo predation without going extinct.

But now a combination of small population sizes of some threatened species and exacerbating factors such as habitat loss, foxes and cats means some threatened species could be vulnerable to even low levels of dingo predation. Predation by dingoes should therefore be a key consideration when attempting to conserve or restore threatened species.

Dietary studies are one way we can understand how dingoes interact with other species. Our study also highlights that we still have much to learn about our native top predator. In many parts of Australia, the favourite foods of dingoes are still a mystery.

The authors acknowledge the contribution of Naomi Davis, Dave Forsyth, Mike Letnic, Russell Palmer, Joe Benshemesh, Glenn Edwards, Jenny Lawrence, Lindy Lumsden, Charlie Pascoe, Andy Sharp, Danielle Stokeld, Cecilia Myers, Georgeanna Story, Paul Story, Barbara Triggs, Mark Venosta and Mike Wysong to this research.

Tim Doherty, Research Fellow, Deakin University; Chris Dickman, Professor in Terrestrial Ecology, University of Sydney; Dale Nimmo, Associate professor/ARC DECRA fellow, Charles Sturt University; Euan Ritchie, Associate Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University, and Thomas Newsome, Lecturer, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Why the WA government is wrong to play identity politics with dingoes

Bradley Smith, CQUniversity Australia; Euan Ritchie, Deakin University, and Lily van Eeden, University of Sydney

Australia’s Commonwealth Coat of Arms depicts two iconic native animals – the kangaroo and the emu. Both are unquestionably fair dinkum Aussies, unique to this continent and having lived here for a very long time. A “very long time”, according to Australian legislation (the EPBC Act 1999), is any species having been present since before the year 1400.

But in Western Australia, under the state’s Biodiversity Conservation Act 2016, no native animal is guaranteed protection. The Act includes a caveat whereby the relevant minister may determine that a native species is in fact, not.

This week, WA’s environment minister Stephen Dawson did just that, declaring that from January 1, 2019, the dingo, Australia’s native canine, will no longer be classified as native fauna.

The dingo does meet the federal government’s criterion, having lived in Australia as a wild canid for an estimated 5,000 years. But under the planned changes in WA, the dingo will lose its current listing as “unprotected fauna”, and will from next year be considered indistinguishable from either the common domestic dog or feral dogs.

What is a species anyway?

According to the biological species concept, a species is a group that has the ability to interbreed and produce viable, fertile offspring. Dingoes, dogs and other canids do interbreed (or “hybridise”), and indeed this is one of the key reasons why the pure dingo is listed as vulnerable by the International Union for the Conservation of Nature.

But this ability to hybridise is also one of the main justifications cited by the WA government in its decision to revoke the dingo’s citizenship (the fact sheet has since been removed from the website, but can be accessed here). The rationale is that if dingoes and dogs are technically the same species, why should dingoes get special treatment?

However, the biological species concept is problematic when applied to canids. If you lump dingoes and dogs together because they readily interbreed, then logically we must do the same for wolves, coyotes, jackals or other canids that can also interbreed (and have done for millenia).

It’s hard to imagine anyone seriously suggesting that a grey wolf and a pug are the same species. This suggests that this criterion alone is insufficient to solve the conundrum. Indeed, there are at least 32 different species concepts, clearly illustrating the difficulty of defining a single rule by which all organisms should abide.

Despite this, a recent paper that argues the biological species concept should be applied to dingoes, was cited as supporting evidence by the WA government. Adopting this narrow interpretation of taxonomy is perhaps somewhat premature. It ignores other investigations that provide evidence to the contrary. Given the contention around defining species, it seems unwise to determine the species status of dingoes independently of other, more comprehensive evidence and argument.

Distinguishing dingoes

All canids share similarities, but their differences are also many and marked. The dingo can be distinguished from other dogs in various ways: their appearance, anatomy, behaviour, their role in ecosystems, and their genetics (their evolutionary history and degree of relatedness to other species). Dingoes seem to be largely devoid of many of the signs of domestication.

It is therefore reasonable for the dingo to be considered separately from wolves and domestic dogs, while also acknowledging that they all occupy the same broad species classification, Canis lupus.

Having lived in Australia as free-living, wild populations for around 5,000 years almost exclusively under the forces of natural selection, and separately from any other dog lineage until European arrival, there is no notion of the dingo as a domestic animal gone feral. To classify dingoes as nothing more than “feral domestic dogs” expunges their unique, long and quintessentially wild history. Dingoes are not ecologically interchangeable with any other type of dog, either wild or domesticated.

Australia’s dingo is a recognisable species.
Angus Emmott

Labelling the dingo as a feral domestic dog changes their legal status and removes any current obligations for developing appropriate management plans. This demotion of status could lead to intensified lethal control. Indeed, control may even be legally mandated.

In the absence of thylacines, mainland Tasmanian devils, and other apex predators, the ecological role that the dingo plays in the Australian landscape is vital. Dingoes help to control kangaroo and feral goat populations, and in some cases foxes and cats as well.

Given WA’s remoteness, it remains one of the few bastions of pure dingoes, and as such it presents an opportunity to seek ways to protect them rather than pave the way for their removal. The WA government’s decision also sets a dangerous precedent for the management of dingoes, and indeed other contentious native wildlife, elsewhere in Australia.

How we choose to classify plants and animals might sound like dry science. But it has genuine implications for policy, management and conservation. Our scientific naming systems are vital for helping to organise and understand the rich biological diversity with which we share the planet, but it is important to remember that these systems are informed not just by biology but also by our values.

In this case, economic and political interests appear to have been favoured over wildlife preservation, and given Australia’s unenviable conservation record this is deeply concerning.

Bradley Smith, Senior Lecturer in Psychology, CQUniversity Australia; Euan Ritchie, Associate Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University, and Lily van Eeden, PhD Candidate in Human-Wildlife Conflict, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Why do dingoes attack people, and how can we prevent it?

File 20180725 194155 109dcyu.jpg?ixlib=rb 1.1 — Dingoes are usually solitary, but can forage in groups near human settlements where food is abundant.
Klaasmer/Wikimedia Commons, CC BY-SA

Bill Bateman, Curtin University and Trish Fleming

The case of Debbie Rundle, who was attacked by dingoes at a mine site in Telfer, in Western Australia’s Pilbara region, evokes our instinctive horror at the idea of being attacked by wild animals.

Rundle suffered severe leg injuries in the incident, and said she feared she may have been killed had her colleagues not come to her aid.

We know that there are carnivores throughout the world with the potential to kill us. And while most of us will never come face to face with a hungry wolf, lion, tiger or bear, such attacks do unfortunately still occur.

In the scale of things, such attacks are very uncommon – although that is little consolation to the victim. Australia’s dingoes are no exception; despite some infamous examples, dingo attacks on humans are mercifully rare. But people will still understandably want to know why they happen at all, and what can be done to prevent them.

Why do wild animals attack?

Research on wolf attacks shows that, absent the influence of rabies which can increase wolves’ aggression, two common factors associated with attacks are that they often happen in human-modified environments, and by animals that are habituated to human presence.

These two variables are obviously linked: many species of mammalian carnivore are highly adaptable, and soon learn that human settlements are sources of food, water and shelter.

These human resources can have a profound effect on the behaviour of wild animals. Abundant human food often reduces animals’ aggression towards one another, and can result in the presence of much larger numbers of individuals than normal.

This is equally true of dingoes. Although they are usually observed alone, it is not uncommon to see groups of ten or more dingoes foraging at rubbish dumps associated with mine sites in the Tanami Desert of central Australia. There are thought to be around 100 dingoes that forage in and around the Telfer mine where Rundle was attacked.

Waste food may inadvertently entice animals to human settlements, and this may lead to predators becoming habituated to human presence. In Canada, a young man fell victim to a wolf attack at a mine site; the local wolves were reported to be used to humans, and would even follow rubbish trucks to the tip. They may have come to associate human smells with the provision of food.

Animals that are habituated to humans lose some of their natural wariness towards them. This is typical of many animal species that adapt to urban habitats, and while this may be an appealing trait in squirrels or garden birds, it can be quite different if the animal is a predator capable of attacking a human.

Coyotes can be dangerous, especially when they get used to living in human environments.
Marya/Flickr/Wikimedia Commons, CC BY-SA

In the United States, there have been many reports of coyotes attacking humans. The coyote, like the dingo, is reasonably large (typically weighing 10–16kg) and can be found in close association with urban areas. The coyote’s natural range has expanded as wolves (their competitor) have dwindled, and their numbers have increased in and around cities where they find copious and consistent supplies of food and water.

A survey of reported attacks on humans by coyotes showed that many were “investigative”, often involving the animal trying to steal something they perceived as food from the person. Other attacks by coyotes could be identified as “predatory”, in which the victim was pursued and bitten, and often occurred when the coyotes were in a group.

The Telfer dingo attack similarly appears to have been investigative – a young dingo climbed onto a table and grabbed Rundle’s phone. But the incident turned nasty when Rundle (perhaps understandably) followed the dingo that had her phone; this seemed to trigger a defensive or predatory attack from two other dingoes.

On Queensland’s Fraser Island, more than half of the recorded aggressive incidents by dingoes towards humans happened when the person was walking or running, suggesting that a “chase” response may have been involved.

The Telfer site, like other mine sites, has strict rules about putting waste food in bins, and managers have been proactive in training workers to not feed dingoes, in an attempt to prevent just such attacks. Rundle certainly seems to have followed these rules.

Unfortunately, in her case, other variables contributed to the attack – an investigative approach by one dingo that stole an item (that may have smelled of food) seems to have turned into an aggressive group attack when she followed the animals.

What can we do to prevent such attacks? Mine site managers already do much to reduce the likelihood of such incidents by reducing dingoes’ access to food. Fencing off eating areas or storing food in cages – as is done at Fraser Island – can help in this regard.

Interestingly, many people believe that it is best not to act aggressively when they encounter a large carnivore, but in reality it depends on the species. For wolves and pumas, the best tactic seems to be to shout and throw objects to put them off.

Ultimately, the onus is on individual people to be aware of the potential danger of wild predators, and always to treat them with wariness and respect.

Bill Bateman, Senior Lecturer, Curtin University and Trish Fleming, Associate Professor

This article was originally published on The Conversation. Read the original article.

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