When introduced species are cute and loveable, culling them is a tricky proposition



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Lily van Eeden, University of Sydney; Chris Dickman, University of Sydney; Jeremy T. Bruskotter, The Ohio State University; Mathew Crowther, University of Sydney, and Thomas Newsome, University of Sydney

Almost one in five Australians think introduced horses and foxes are native to Australia, and others don’t want “cute” or “charismatic” animals culled, even when they damage the environment. So what are the implications of these attitudes as we help nature recover from bushfires?

Public opposition to culling programs is often at odds with scientists and conservationists.

These tensions came to the fore last month when scientists renewed calls for a horse-culling program to protect native species in Kosciusko National Park – a move strongly opposed by some members of the public.

To manage the environment effectively, including after bushfires, we need to understand the diversity of opinion on what constitutes a native animal, and recognise how these attitudes can change.

Governments are responding

In Australia, native species are usually defined as those present before European settlement in 1788. Lethal pest control usually targets species introduced after this time, such as horses, foxes, deer, rabbits, pigs, and cats.

But fire makes native fauna more vulnerable to introduced predators. Fire removes ground layer vegetation that small wildlife would use as protective cover. When this cover is gone, these animals are easier targets for predators like cats and foxes.




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Fire almost wiped out rare species in the Australian Alps. Feral horses are finishing the job


State governments have started to respond to this impending crisis. In January, the New South Wales government announced its largest ever program to control feral predators, in an effort to protect native fauna after the fires.

The plan includes 1500-2000 hours of aerial and ground shooting of deer, pigs, and goats and distributing up to a million poison baits targeting foxes, cats, and dingoes over 12 months.

Similarly, the Victorian government announced a A$17.5 million program to protect biodiversity the fires affected, including A$7 million for intensified management of threats like introduced animals.

But will the public be on board? Widespread media coverage of the recent fires and their impacts on wildlife, including the loss of more than a billion animals, might garner support for protecting native wildlife from pests.

On the other hand, efforts to manage animals such as cats and horses might be hampered by a lack of public support for culling charismatic animals that many people value or view as belonging in Australia now.

Different folks, different strokes

The distinctions many Australians draw – native animals are “good” and introduced species are “bad” – shape how people view conservation efforts. A survey we conducted in 2017 found people more likely to disapprove of lethal methods for managing species they perceived to be native.

In the same survey, we found nearly one in five Australians considered horses and foxes to be native to Australia.

This suggests either that a) people lack knowledge of Australia’s natural history or b) people disagree with conservationists’ definition of animal “nativeness”.

Calls to manage horses to prevent environmental degradation in Australian national parks are hugely controversial, with many people arguing the horses belong now.
Shutterstock

Many introduced species, such as horses and foxes, have existed in Australia for more than a century and have established populations across much of the country. It’s unlikely they’ll ever be eradicated.

Some people, including scientists, say we should just accept introduced species as part of Australia’s fauna. They argue current management justifies killing based on moral, not scientific judgements and introduced animals may increase biodiversity.




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But the issue remains extremely divisive. A central tenet of traditional conservation is that humans have a duty to protect native species and ecosystems from the threat introduced species pose. It’s difficult to do this without culling introduced animals.

Animal welfare concerns may also drive opposition to culling, taking the view that all animals, even non-natives, have intrinsic value and the right to live.

What’s more, non-native culling programs can be controversial when the animal is considered “cute” or “charismatic”, or of cultural value. For example, a plan to cull feral horses in the Kosciusko National Park in 2018 was met with public outrage, prompting the NSW government to overturn the decision.

Yet protecting introduced species in national parks goes against the very reason they were created – to conserve native ecosystems and species.

Some animals are more equal than others

When analysing public attitudes towards various species, we must also consider how attitudes shift over time.

In Australia, non-native animals such as domestic camels and donkeys were considered useful for transport and highly valued. But we ultimately turned them loose and relabelled them as pests when we started using cars.

We asked the Australian public whether they viewed dingoes, horses, and foxes as native or non-native in Australia.
van Eeden et al. (2020)

Interestingly, we’ve already accepted some introduced species as native. Humans brought dingoes to Australia at least 3,500 years ago. They’re described as native under Australian biodiversity legislation, and 85% of our 2017 survey participants considered dingoes to be native.

Perhaps its only a matter of time until more recently arrived species like horses and foxes are counted as native. Some scientists argue this shift should be based on how ecosystems and species adapt to these new arrivals. For example, some small Australian mammals show fear of dingoes or dogs, but they haven’t yet learnt to fear cats.

Native species can be pests too

Native species, such as kangaroos and possums, may also be culled if they’re perceived to be overabundant or damaging economic interests like agriculture.




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While the plight of bushfire-affected koalas on Kangaroo Island attracted considerable media interest, and the immediate welfare of any animal affected by fires is always a concern, koalas were actually introduced there.

They’ve been managed as a pest on Kangaroo Island for more than 20 years, and it’s unlikely the rescued koalas will be returned to the island. In this case, public concern transcends the distinction between native and introduced.

Public perception is important

We might never all agree on how best to manage native and non-native species. But effective environmental management, including after bushfires, requires understanding the diversity of opinion.

Doing so can help to develop management plans the public supports and allow effective communication about management that is controversial.

In fact, the NSW Office of Environment and Heritage did undertake an extensive public consultation process in developing their horse management plan for Kosciuszko National Park, but it wasn’t used after the “brumby bill” gave horses protection in 2018.




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With human lives and many animal lives lost, response to the bushfires is already highly emotive. Failure to consider public attitudes towards managing animals will lead to backlash, wasted money and time, and continuing decline of the native species whose conservation is the goal of these actions.The Conversation

Lily van Eeden, PhD Candidate in Human-Wildlife Conflict, University of Sydney; Chris Dickman, Professor in Terrestrial Ecology, University of Sydney; Jeremy T. Bruskotter, Professor, School of Environment and Natural Resources, The Ohio State University; Mathew Crowther, Associate professor, University of Sydney, and Thomas Newsome, Lecturer, University of Sydney

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

Fire almost wiped out rare species in the Australian Alps. Feral horses are finishing the job



Feral horses are destroying what little threatened species habitat was spared from bushfire.
Invasive Species Council

Jamie Pittock, Australian National University

On Friday I flew in a helicopter over the fire-ravaged Kosciuszko National Park. I was devastated by what I saw. Cherished wildlife species are at grave risk of extinction: those populations the bushfires haven’t already wiped out are threatened by thousands of feral horses trampling the land.

The New South Wales park occupies the highest mountain range in Australia and is home to plants and animals found nowhere else in the world. Many of these species are threatened, and their survival depends on protecting habitat as best we can.




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Double trouble as feral horse numbers gallop past 25,000 in the Australian Alps


Kosciuszko National Park provides habitat for two species of corroboree frog (critically endangered), the alpine she-oak skink (endangered), broad-toothed rat (vulnerable) and stocky galaxias (a critically endangered native fish), among other threatened species.

As the climate has warmed, the cool mountain habitat of these species is shrinking; bushfires have decimated a lot of what was left. Feral horses now threaten to destroy the remainder, and an urgent culling program is needed.

Devastation as far as the eye can see on the burnt western face of Kosciuszko National Park.
Jamie Pittock

Not a green leaf in sight

Australia’s plants and ecosystems did not evolve to withstand trampling by hard-hooved animals, or their intensive grazing. Unfortunately, the New South Wales government has allowed the population of feral horses in the park to grow exponentially in recent years to around 20,000.

I flew over the northern part of the park with members of the Invasive Species Council, who were conducting an urgent inspection of the damage. Thousands of hectares were completely incinerated by bushfires: not a green leaf was visible over vast areas. A cataclysm has befallen the western face of the mountains and tablelands around Kiandra and Mount Selwyn.




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Further north and east of Kiandra the fires were less intense and burnt patchily. On Nungar Plain the grassland and peat wetlands were only lightly burnt, and the first green shoots were already visible along the wetlands of the valley floor.

At first, I wondered if the fires may have spared two animals which live in tunnels in the vegetation on the sub-alpine high plains: the alpine she-oak skink and broad-toothed rat (which, despite the name is a cute, hamster-like creature).

The hamster-like broad toothed rat.
Flickr

But not only was their understory habitat burnt, a dozen feral horses were trampling the peat wetlands and eating the first regrowth.

On the unburnt or partially burnt plains a few ridges over, 100 or more horses were mowing down the surviving vegetation.

Precarious wildlife refuges

Next we flew over a small stream that holds the last remaining population of a native fish species, the stocky galaxias. A small waterfall is all that divides the species from the stream below, and the jaws of the exotic trout which live there.

The aftermath of the fires means the last refuge of the stocky galaxias is likely to become even more degraded.

Over the years, feral horses have carved terraces of trails into the land causing erosion and muddying the stream bank. As more horses congregate on unburnt patches of vegetation after the fires, more eroded sediment will settle on the stream bed and fill the spaces between rocks where the fish shelter. Ash runoff entering the stream may clog the gills of the fish, potentially suffocating them.

An Alpine she-oak skink.
Renee Hartley



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Many key wetland habitats of the southern and northern corroboree frogs have also been burnt. These striking yellow and black frogs nest in wetland vegetation.

A corroboree frog.
Flickr

We hovered over a key wetland for the northern corroboree frog that had not been burnt, deep in the alpine forest. A group of feral horses stood in it. They had created muddy wallows, trampled vegetation and worn tracks that will drain the wetland if their numbers are not immediately controlled.

Horses out of control

Five years ago a survey reported about 6,000 feral horses roaming in Kosciuszko National Park. By 2019, the numbers had jumped to at least 20,000.

We saw no dead horses from the air. Unlike our native wildlife, most appear to have escaped the fires.




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Flying down the upper Murrumbidgee River’s Long Plain, I saw large numbers of feral horses gathered in yet more wetlands. Displaced by the fires to the south and west, they were already trampling the mossy and heathy wetlands that store and filter water in the headwaters.

The Murrumbidgee River is a key water source for south-east Australia. The horses stir up sediment and defecate in the water. They create channels which drain and dry the wetlands, exposing them to fire.

One-third of Kosciuszko National Park has been burnt out and at the time of writing the fires remain active. Feral horses are badly compounding the damage.

If we don’t immediately reduce feral horse numbers, the consequences for Kosciuszko National Park and its unique Australian flora and fauna will be horrendous.

Responsible managers limit the numbers of livestock on their lands and control feral animals. The NSW government must repeal its 2018 legislation protecting feral horses in Kosciuszko National Park, and undertake a responsible control program similar to those of the Australian Capital Territory and Victorian governments.

Without an emergency cull of feral horses in Kosciuszko National Park, burnt vegetation may not fully recover and threatened species will march further towards extinction.The Conversation

Jamie Pittock, Professor, Fenner School of Environment & Society, Australian National University

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

Double trouble as feral horse numbers gallop past 25,000 in the Australian Alps



Feral horses are a growing problem for the NSW government.
Shutterstock/Constantin Stanciu

Don Driscoll, Deakin University; David M Watson, Charles Sturt University, and Euan Ritchie, Deakin University

Feral horse numbers have more than doubled in the past five years in the Australian Alps, according to results just released from the Australian Alps Feral Horse Aerial Survey. In one of the three survey blocks, North Kosciuszko, feral horse numbers have risen from an estimated 3,255 in 2014 to 15,687 in 2019, a near five-fold increase.

Scientists warned the government that very high numbers of horses would be the inevitable consequence of its inaction over horse management.

With no horses removed in 2017 or 2018, and only 99 removed this year, the population has been allowed to grow at about 23% per year, close to the maximum of about 25% known for feral horses.

More than just allowing numbers to increase, the NSW parliament legislated to protect feral horses within Kosciuszko National Park, effectively prioritising the preservation of horse populations over native alpine species and environmental values, where they are in conflict.

This was despite the strong advice from scientists, and amid substantial controversy around the origins and timing of the bill.

A potentially fatal feral horse problem

High feral horse numbers forced the closure of the popular Blue Waterholes campground in November, after substantial risks and several injuries to visitors were reported. Freedom of information requests were needed to bring to light crashes between cars and feral horses in Kosciuszko.

Despite the NSW government trying to keep this information from reaching the public, several incidents of feral horses being struck by vehicles have now been reported.

The community group Reclaim Kosci has warned it is only a matter of time before someone is killed in a collision with a feral horse unless numbers are drastically and rapidly reduced.

Government warned of potentially deadly car crashes with feral horses.
Shutterstock/Trevor Charles Graham

Besides impacts on people, the lack of effective feral horse policy in NSW has now set the stage for another mass animal welfare disaster.

With an estimated 25,318 feral horses distributed across the surveyed area (more than 7,400 square kilometres) of the Australian Alps, many thousands of horses will face starvation when the region next burns. This is predictable, inevitable and tragically also completely avoidable had effective feral horse control been implemented.

The prolonged drought hitting Australia has worsened the impacts of horses in the high country. Plants already struggling to survive are being trampled and grazed, and areas around standing water resemble feedlots.

These impacts will worsen over summer, both for the national park and the horses themselves, with herds suffering in the heat and struggling to survive. Horses starved to death along the snowy river in Kosciuszko in 2018.

Now many more animals are at risk of this fate because scientifically-supported solutions have been dismissed by NSW deputy premier John Barilaro.

Natural wildlife threatened

Evidence presented at the Kosciuszko Science Conference and research published earlier this year showed how a broad range of Alpine species and ecosystems were being affected by feral horses. These effects will now be more intense and occur across more of Australia’s ecologically sensitive and biodiverse alpine environments.

For example, the native broad toothed rat depends on dense vegetation along watercourses. With feral horses eating out or trampling plants along streams, these delightful, rotund fur-balls may lose their homes, and hence be more exposed to the elements and predators.

Right now, feral horses are reducing the habitat for these animals, causing already threatened populations to become smaller and more fragmented. As these small populations blink into extinction we can expect widespread losses across the national park.

A colourful corroboree frog faces more destruction to breeding grounds.
Flickr/Australian Alps collection – Parks Australia, CC BY-ND

Corroboree frogs will now be under enormous pressure. We already know feral horses destroy the wetlands these iconic yellow-striped black frogs depend on for breeding. This destruction will likely now impact many more swamps, reducing breeding success and reducing options for reintroduction of this critically endangered frog.

Another species, the Stocky Galaxias, teeters on the brink of extinction. This small native fish now only lives in a 3km stretch of stream in Kosciuszko National Park. Feral horses trample the river banks and rip out vegetation that causes silt to accumulate in the stream.

This is disastrous for the fish, which breed beneath boulders in the stream. If silt fills up the gaps beneath boulders, there is no place for the fish to lay eggs.

The high numbers of feral horses in Kosciuszko mean this process of stream destruction will likely worsen, potentially hastening the demise of this species unique to Kosciuszko National Park.

New management plan needed

Hope for change now rests with the new feral horse management plan being developed by the recently established Kosciuszko National Park Wild Horse Community Advisory Panel and the Wild Horse Scientific Advisory Panel. The community panel has expressed interest in working with the scientific panel, and such collaboration will be essential for making progress.




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These committees will need to consider all options for resolving this human safety, animal welfare, and ecological crisis. Although trapping is crueller and many times more expensive than aerial culling, if the trapping effort is substantially ramped up across the park, it could potentially limit population growth and reduce horse numbers.

Aerial culling, despite being the most cost-effective and humane method to lower the horse population size and reduce impacts, is misrepresented by the pro-brumby lobby and sections of the media as cruel, and hence has been deemed unacceptable. These costs, and animal welfare and political trade-offs, must be carefully considered by the committees.

The scientific committee said the draft plan for action will be open for comment in February 2020 to meet NSW environment minister Matt Kean’s deadline for a final plan by May 1, 2020. This rapid timeframe is absolutely essential, as the increase of feral horses in the Alpine National Park will not abate any time soon without urgent and substantial control measures.The Conversation

Don Driscoll, Professor in Terrestrial Ecology, Deakin University; David M Watson, Professor in Ecology, Charles Sturt University, and Euan Ritchie, Associate Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University

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

Non-native species should count in conservation – even in Australia



Australia is home to many new species, including wild camels found nowhere else on Earth.
Author provided

Arian Wallach, University of Technology Sydney; Chelsea Batavia, Oregon State University; Danielle Celermajer, University of Sydney; Daniel Ramp, University of Technology Sydney; Erick Lundgren, University of Technology Sydney, and Esty Yanco, University of Technology Sydney

As the world struggles to keep tabs on biodiversity decline, conservation largely relies on a single international database to track life on Earth. It is a mammoth and impressive undertaking – but a glaring omission from the list may be frustrating conservation efforts.




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In defence of invasive alien species



The International Union for the Conservation of Nature’s Red List aims to be a “complete barometer of life”. But non-native wildlife is excluded from the list.

Our study, published today in the journal Conservation Biology, questions the wisdom of this omission. It means, for example, vulnerable species facing existential threats in their “home country” may be exterminated freely in another. Excluding these animals, such as wild camels in Australia, and rare Australian frogs living overseas, distorts conservation science.

What counts as ‘native’?

The concept of “native” draws a sharp line between species that count and those that don’t. It is essentially an ethical choice, and a disputed one at that. Regardless of whether one defends or disputes the concept, it is problematic to use a moral term to filter a critical source of scientific data.

Trash Animals: How We Live with Nature’s Filthy, Feral, Invasive, and Unwanted Species.

The invisible components of biodiversity – those populations excluded from conservation’s definition of life – can be found in trash lists, where they are described as invasive, aliens, pests, and feral.

So what does the world look like if we include all wildlife in biodiversity assessments? We rummaged around in the “trash piles” to find out.

When all life counts

By focusing on Australian non-native vertebrate species – amphibians, birds, fishes, mammals, and reptiles – we did something many conservationists would find unthinkable. We added unloved species such as feral cats, cane toads, the Indian myna, and carp to Australia’s biodiversity counts.

We created maps showing the range of 87 species whose ancestors were introduced into Australia, and 47 species native to Australia that were introduced elsewhere, since European colonisation.

Many of these so-called invasive species are at risk of extinction in their native ranges; 32% are assessed as threatened or decreasing in the Red List. For 15 of them, non-native ranges provide a lifeline.

Australia’s vertebrate species that are threatened or near threatened in their native ranges with significant populations overseas. From left-to-right: Indian hog deer, banteng, wild cattle, wild water buffalo, wild camel; wild goat, carp, wild donkey, brumby, Mozambique tilapia; European rabbit, Javan rusa, sambar deer, and (emigrants) green and golden bell frog, growling grass frog.
Arian Wallach et al

Not only does Australia contribute to the survival and flourishing of these species, but immigrant vertebrates have also added 52 species to the number of vertebrate species in Australia (after accounting for extinctions).

This number in no way indicates that non-native species replace or make up for those that have been lost. And it does not exonerate humans of their role in causing extinctions. But the current data do not even allow us to acknowledge that these species exist.

Because they are not counted in conservation, these non-native populations are subjected to mass eradication programs. Paradoxically, in assessing how such programs are justified, we found conservation is the most frequently cited reason for killing these wild animals.

Dromedary camels were extinct in the wild for some 5,000 years until they “went feral” in Australia, where they are now endemic. Rather than celebrating what is arguably the most extraordinary rewilding event in the world, wild camels were declared a pest. Between 2009 and 2013, Australia spent A$19 million to gun down 160,000 individuals of a species found nowhere else on Earth in the wild.

Likewise, 89% of the global distribution of Javan rusa, a deer species vulnerable to extinction, is in Australia. As pest, they are culled and hunted for sport.

Stated motivations for killing Australia’s immigrant vertebrate wildlife, shown as percentages of species targeted per taxonomic group. Numbers above bars indicate absolute number of species targeted.

Nativism not only renders countless species invisible, along with their unique and fascinating ecologies; it also exposes them to unfettered, unscientific, unmonitored, and unlamented mass killing programs.




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Mass killing of non-native species, if questioned at all, is generally explained as protecting native species. But ecology is complex. One cannot simply assume that all non-native populations, in all contexts, do nothing but harm.

Where non-native species do contribute to the loss of native species, humans need to confront the ethical complexities and shoulder real responsibility, rather than simply reach for a gun as a first solution.

In many situations changing harmful human behaviours, like persecuting apex predators such as dingoes, can solve problems that appear to be caused solely by non-native species.

Irrespective of whether we value non-native species or not, there is no scientific justification for expunging large swaths of the living world from conservation data. Smuggling ethically dubious distinctions into data harms conservation science, and has grave repercussions.




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Persisting with the assumption that we have the right to pick and choose which species “count” looks like playing God. By now, we should have learned we must not.The Conversation

Arian Wallach, Lecturer, Centre for Compassionate Conservation, University of Technology Sydney; Chelsea Batavia, Postdoctoral research associate, Oregon State University; Danielle Celermajer, Professor of Sociology and Social Policy, University of Sydney; Daniel Ramp, Associate Professor and Director, Centre for Compassionate Conservation, University of Technology Sydney; Erick Lundgren, PhD Student, Centre for Compassionate Conservation, University of Technology Sydney, and Esty Yanco, PhD Candidate, Centre for Compassionate Conservation, University of Technology Sydney

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.




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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.




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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.




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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.




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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.




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The Conversation


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.

Eat your heart out: native water rats have worked out how to safely eat cane toads



Water rats in Western Australia are safely hunting cane toads.
Author provided

Marissa Parrott, University of Melbourne; Sean Doody, University of Newcastle, and Simon Clulow, Macquarie University

Australia’s water rats, or Rakali, are one of Australia’s beautiful but lesser-known native rodents. And these intelligent, semi-aquatic rats have revealed another talent: they are one of the only Australian mammals to safely eat toxic cane toads.

Our research, published today in Australian Mammalogy, found water rats in Western Australia adapted to hunt the highly poisonous toads less than two years after the toads moved into the rats’ territory.




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The rats, which can grow to over 1kg, are the only mammal found to specifically target large toads, neatly dissecting the toads to eat their hearts and livers while avoiding the poisonous skin and glands.

Water rats

Water rats are nocturnal and specially adapted to live in waterways, with webbed feet and soft water-resistant fur. Their fur is so impressive there was once a thriving water rat fur industry in Australia.

They can be found in lakes, rivers and estuaries, often living alongside people, in New South Wales, Queensland, Tasmania, South Australia, far north and southwest Western Australia, the Northern Territory, and Victoria, where they can even be seen along St Kilda Pier.

Water rats are also highly intelligent, as shown by their rapid adaptation to hunting and eating one of Australia’s most toxic introduced species – the invasive cane toad.

Cane toads were introduced to Australia in 1935 in an ill-fated attempt to control the cane beetle. They have spread across the north of the country at up to 60km per year, leaving devastation in their wake. Many native species, such as northern quolls, yellow-spotted monitors, and crocodiles, have suffered widespread declines, and in some cases local extinctions, as a result of eating cane toads.

The toads secrete a toxin in their parotoid glands (on the back, neck and shoulders) that can be fatal even in very small doses.

A cane toad at our field site in the Kimberley.
Marissa Parrott, Author provided

Eat your heart out

Cane toads arrived at our field site in the Kimberley, Western Australia, in 2011-12, leading to a crash in the populations of predators including numerous lizards and northern quolls.

However, in 2014 we found a creek dotted with the bodies of cane toads that had clearly been attacked. Every morning we discovered up to five new dead toads with small, near-identical incisions down their chest in just a five-metre stretch of creek. What was using almost surgical precision to attack these toads?

Post-mortem analysis showed that in larger toads the heart and liver had been removed, and the gall bladder (which contains toxic bile salts) neatly moved outside the chest cavity. In medium-sized toads, besides the removal of the heart and liver, one or both back legs had been stripped of their toxic skin and the muscle also eaten.

The finding intrigued us enough to dissect waterlogged and rotting toad bodies in 40℃ heat. Using remote infrared camera footage and analysis of the bites left on the muscle, we found our clever attacker – the native water rat!

A water rat caught on camera hunting for cane toads in the Kimberley.
Marissa Parrott, Author provided

What kind of toads are rats eating?

While there have been anecdotal reports of water rats eating toads in Queensland and the Northern Territory, there were no published reports of this in Western Australia, where the toad was a more recent arrival.

We also didn’t know whether rats could tolerate the toad toxins, or were targeting non-toxic parts of the body. And we wanted to find out whether the rats were targeting small (and less toxic) toads, as some other rodent species do, or were deliberately going after larger toads which are a better source of food.

During our study we captured and measured more than 1,800 cane toads in just 15 days in the vicinity of the water rats’ creek. The vast majority, 94%, were medium-sized; 3.5% were small (less than 4cm long); and just 2.5% were large (greater than 10cm long).

But despite medium toads being far more common, three quarters of the dead toads we found were large, and the remainder were medium. No small toad bodies were found or observed being attacked.

While some species, such as keelback snakes and several birds (including black and whistling kites, and crows) can eat cane toads, there has been less evidence of mammals hunting this new type of prey and living to tell the tale.

Some rodents can eat small juvenile toads, but no rodents have been documented specifically targeting large toads. In our case, water rats preferred to eat large toads, despite medium-sized toads outnumbering them by 27 to 1.

A water rat eating at Healesville Sanctuary.

We’re not sure whether water rats have very rapidly learned how to safely attack and eat cane toads, or if they are adapting a similar long-term hunting strategy that they may use to eat toxic native frogs.

Water rats are very well placed to pass on hunting strategies, as they care for their offspring for at least four weeks after they finish producing milk. This could help spread the knowledge of toad hunting across streams and creeks over time.




Read more:
The economics of ‘cash for cane toads’ – a textbook example of perverse incentives


While this behaviour seems to be confined to local populations, if these tactics spread, water rats may be able to suppress toad populations when they reach water bodies – another small line of defence against this toxic killer.The Conversation

Marissa Parrott, Reproductive Biologist, Wildlife Conservation & Science, Zoos Victoria, and Honorary Research Associate, BioSciences, University of Melbourne; Sean Doody, Conjoint Fellow, University of Newcastle, and Simon Clulow, MQ Research Fellow, Macquarie University

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