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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We’ve cracked the cane toad genome, and that could help put the brakes on its invasion

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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.

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

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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.

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.

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Australia: Cane Toads

How indigenous expertise improves science: the curious case of shy lizards and deadly cane toads

The Balanggarra Rangers are land management representatives of the Balanggarra people, the indigenous traditional owners of the East Kimberley. (L-R) Wes Alberts, Bob Smith (coordinator) James ‘Birdy’ Birch, Isiah Smith, Quentin Gore.
The Kimberley Land Council, Author provided

Georgia Ward-Fear, University of Sydney and Rick Shine, University of Sydney

It’s a common refrain – western ecologists should work closely with indigenous peoples, who have a unique knowledge of the ecosystems in their traditional lands.

But the rhetoric is strong on passion and weak on evidence.

Now, a project in the remote Kimberley area of northwestern Australia provides hard evidence that collaborating with Indigenous rangers can change the outcome of science from failure to success.

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We’ve cracked the cane toad genome, and that could help put the brakes on its invasion

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Fighting a toxic invader

This research had a simple but ambitious aim: to develop new ways to save at-risk predators such as lizards and quolls from the devastating impacts of invasive cane toads.

Cane toads are invasive and highly toxic to Australia’s apex predators.
David Nelson

All across tropical Australia, the arrival of these gigantic alien toads has caused massive die-offs among meat-eating animals such as yellow-spotted monitors (large lizards in the varanid group) and quolls (meat-eating marsupials). Mistaking the new arrivals for edible frogs, animals that try to eat them are fatally poisoned by the toad’s powerful toxins.

Steep population declines in these predators ripple out through entire ecosystems.

But we can change that outcome. We expose predators to a small cane toad, big enough to make them ill but not to kill them. The predators learn fast, and ignore the larger (deadly) toads that arrive in their habitats a few weeks or months later. As a result, our trained predators survive, whereas their untrained siblings die.

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What is a waterless barrier and how could it slow cane toads?

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Conservation ‘on Country’

But it’s not easy science. The site is remote and the climate is harsh.

We and our collaborators, the Western Australian Department of Biodiversity, Conservation and Attractions, decided at the outset that we needed to work closely with the Indigenous Traditional Owners of the east Kimberley – the Balanggarra people.

So as we cruised across the floodplain on quad bikes looking for goannas, each team consisted of a scientist (university-educated, and experienced in wildlife research) and a Balanggarra Indigenous ranger.

Although our study species is huge – a male yellow-spotted monitor can grow to more than 1.7 metres in length and weigh more than 6kg – the animals are well-camouflaged and difficult to find.

Over an 18-month study, we caught and radio-tracked more than 80 monitors, taught some of them not to eat toads, and then watched with trepidation as the cane toad invasion arrived.

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Excitingly, the training worked. Half of our trained lizards were still alive by the end of the study, whereas all of the untrained lizards died soon after toads arrived.

That positive result has encouraged a consortium of scientists, government authorities, conservation groups, landowners and local businesses to implement aversion training on a massive scale (see www.canetoadcoalition.com), with support from the Australian Research Council.

A yellow-spotted monitor fitted with a radio transmitter in our study. This medium-sized male was trained and lived for the entirety of the study in high densities of cane toads.
Georgia Ward-Fear, University of Sydney

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Cross-cultural collaboration key to success

But there’s a twist to the tale, a vindication of our decision to make the project truly collaborative.

When we looked in detail at our data, we realised that the monitor lizards found by Indigenous rangers were different to those found by western scientists. The rangers found shyer lizards, often further away from us when sighted, motionless, and in heavy cover where they were very difficult to see.

Gregory Johnson, Balanggarra elder and ranger.
Georgia Ward-Fear

We don’t know how much the extraordinary ability of the rangers to spot those well-concealed lizards was due to genetics or experience – but there’s no doubt they were superb at finding lizards that the scientists simply didn’t notice.

And reflecting the distinctive “personalities” of those ranger-located lizards, they were the ones that benefited the most from aversion training. Taking a cautious approach to life, a nasty illness after eating a small toad was enough to make them swear off toads thereafter.

In contrast, most of the lizards found by scientists were bold creatures. They learned quickly, but when a potential meal hopped across the floodplain a few months later, the goanna seized it before recalling its previous experience. And even holding a toad briefly in the mouth can be fatal.

Comparisons of conditions under which lizards were initially sighted in the field by scientists and Indigenous rangers (a) proximity to lizards in metres (b) density of ground-cover vegetation (>30cm high) surrounding the lizard (c) intensity of light directly on lizard (light or shade) (d) whether the lizard was stationary or moving (i.e. walking or running). Sighting was considered more difficult if lizards were further away, in more dense vegetation, in shade, and stationary.
Georgia Ward-Fear, University of Sydney

As a result of the intersection between indigenous abilities and lizard personalities, the overall success of our project increased as a result of our multicultural team.

If we had just used the conventional model – university researchers doing all of the work, indigenous people asked for permission but playing only a minor role – our project could have failed, and the major conservation initiative currently underway may have died an early death.

So our study, now published in Conservation Letters, provides an unusual insight – backed up by evidence.

Moving beyond lip service, and genuinely involving Indigenous Traditional Owners in conservation research, can make all the difference in the world.

Georgia Ward-Fear (holding a yellow-spotted monitor) with Balanggarra Rangers Herbert and Wesley Alberts.
David Pearson, WA Department of Biodiversity, Conservation and Attractions

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This research was published in collaboration with James “Birdy” Birch and his team of Balanggarra rangers in the eastern Kimberley.

Georgia Ward-Fear, Post doctoral fellow and Conservation Ecologist , University of Sydney and Rick Shine, Professor in Evolutionary Biology, University of Sydney

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

What is a waterless barrier and how could it slow cane toads?

A dam near Gemtree, Northern Territory.
Shutterstock

Mike Letnic, UNSW

A federal parliamentary inquiry into stopping cane toads’ relentless march across Australia has proposed creating “waterless barriers” in the semi-arid land between Western Australia’s Kimberley and Pilbara regions.

Because cane toads need regular access to water to survive, the plan is to fence off man-made watering points like dams and tanks, creating the equivalent of a firebreak the toads cannot cross.

My colleagues and I have been working with the federal inquiry to create this proposal. Here are the facts.

What is a waterless barrier?

There are large areas of Australia that are naturally dry. Except after big rains, there’s very little above-ground water. When people began farming sheep and cattle out in the western ranges, they created artificial water points with the help of dams, tanks and bores.

These water points are refuges for cane toads during droughts and act as stepping-stones when it rains, because the toads can move safely from point to point. This is how they are colonising large areas of Australia.

But if the toads can’t reach open water they cannot live through a dry season. The proposal aims to restrict the toads’ access to the water, but still let the cattle drink.

The poisonous cane toads are considered non-native pests in Australia.
Shutterstock

What kind of fences are we talking about?

Many water sources are actually already inaccessible to cane toads. Steel or plastic tanks filled from pipelines or underground dams cannot be reached. Troughs give a very limited supply.

The main problem comes from turkeynest dams (these are classic dams: pools of water in the ground with a mounded earth edge). My colleagues and I did research years ago that found a simple 60cm fence is enough to keep cane toads out.

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This doesn’t mean fencing dams is easy: the stations where this would be most helpful are very remote and have plenty of water sources, so fencing (and maintaining) them all presents a logistical hurdle. However many stations are increasingly replacing dams with tanks, which serve the same purpose (and lose far less water to leakage and evaporation).

Cane toads need moisture to survive.
Shutterstock

Another promising development is the number of farmers installing “cut-off switches” for the pumps that fill dams. This is a move away from the older system of turning on a pump and leaving it on until the generator ran out of fuel – perhaps days later. This meant considerable overflow, and created ideal conditions for cane toads. Tanks with solar panels and a cut-off switch that senses when a trough is full can save farms water, power and money, as well as stranding cane toads.

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Yes, you heard right: more cane toads really can help us fight cane toads

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Would it affect native animals?

It’s true some of these dams are now part of the landscape – they’ve been there for a long time. On the other hand, we’re talking about areas that did not originally have much above-ground water before people showed up, and most animals native to the area don’t really need the water (of course, they will drink it if it’s there).

The other part of the equation is the presence of cane toads seriously threatens native wildlife. Cane toads are poisonous and kill native predators, with devastating effects to the environment.

Herd cows drinking water from a Northern Territory dam.
Shutterstock

How big does the barrier need to be, and won’t the rains let the toads cross anyway?

The cattle stations in northern Australia are huge – often 5,000ha. On this scale, just a handful of stations could make a huge difference.

Research suggests a barrier of 50km across could stop toads in their tracks.

The distance a toad can travel in a day varies highly with the environment and weather. In a hot, humid environment a toad might be able to travel roughly 20-30km during a wet season; during cold or dry weather they’re stuck where they are.

Therefore even after heavy rains there won’t be enough water in standing puddles or river beds to let the toads cross the waterless barrier. The puddles would dry out, leaving the toads stranded and without access to dams they would quickly die.

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

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Why should we do it?

Cane toads haven’t been found in this part of Australia, but we believe they will be soon. By creating waterless barriers we can cut them off.

Excitingly, this strategy also has potential to be used in other parts of the country to push cane toads back, reclaiming invaded areas.

Most of the pests Australia has really gone to war against affect agriculture. Cane toads, on the other hand, are an environmental pest: they wreak havoc on native fauna, but have comparatively little impact on cash crops.

Eradication of environmental pests receives comparatively little resources. This proposal would be both a win against a devastating invader, and also a symbol of how much we care for our natural environment, and how important it is to protect it.

Mike Letnic, Professor, Centre for Ecosystem Science, UNSW

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

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

It is estimated there are now more than 200 million cane toads across Queensland and northern New South Wales.
Shutterstock

David Smerdon, The University of Queensland

Economics teachers can all thank Pauline Hanson for providing an excellent example to add to their classes.

Indeed, it’s rare that Economics 101 lessons are as readily on display as in the Queensland senator’s “cash for cane toads” proposal.

Both textbook wisdom and historical failures tell us the plan won’t work.

Hanson’s proposal involves paying welfare recipients 10 cents for each toad they collect (alive) and hand over to their local council. The council would then kill the toads humanely in large freezers.

The senator is right to be concerned about the cane toad problem. Introduced in the 1930s as a biological fix to control native beetles eating sugar cane crops, the animals have prospered with devastating impact on native flora and fauna. It’s estimated there are now more than 200 million across Queensland and northern New South Wales.

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We’ve cracked the cane toad genome, and that could help put the brakes on its invasion

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They carry toxins at all stages of their life cycle, including as eggs. Ingesting the toxin is fatal to many Australian species. Their voracious appetites both deplete insect populations such as honey bees and threaten the food sources of other native animals.

The reason Hanson’s idea is fundamentally flawed, both in theory and in practice, has to do with incentives.

A native of Latin America, the cane toad has adapted well to Australia due to the lack of natural predators. Toads have spread from Queensland as far west as Broome, Western Australia.
http://www.shutterstock.com

History repeating

Incentives are central to economics. They are ingrained in the laws of demand and supply, and the setting of interest rates and taxes.

Humans react to incentives. The key is setting them just right by accounting for all of the costs involved.

This is the most obvious and least interesting problem with the scheme. In NSW and Queensland, you can earn 10 cents by returning an empty drink container to your local supermarket. That’s a task exponentially easier than catching a cane toad and delivering it alive to your local council chambers.

If it were just a case of the incentives being too low, the solution would be simple: raise the price.

However, this would run into a surprising phenomenon called the Cobra effect. Also known as “perverse incentives”, it describes a situation in which a seemingly well-intentioned proposal actually makes things much worse.

The Cobra effect is named after a curious incident from British Colonial India. Faced with a cobra outbreak, the local government of Delhi enacted a cash-for-cobras scheme, with initial success. But as cobras became harder to find, the locals responded to the incentives in a completely logical way: they started breeding the snakes to claim their bounties. When the scheme was scrapped, breeders released their now-worthless snakes, resulting in the city having more cobras than before the scheme.

A similar case comes from French-run Vietnam.

When the colonial government built a sewerage system under Hanoi early in the 20th century, it inadvertently helped create a rat plague. Its solution was a cash-for-rats scheme – though to save the government having to dispose of hundreds of thousands of rat carcasses, it only required collectors turning in a rat’s tail to claim their bounty.

Crowd displeasers

The consequences this time were not only the creation of pop-up rat-breeding farms, but also hordes of tail-less rats roaming the city streets.

Of course, at its current pittance of 10 cents a toad, Hanson’s proposal is unlikely to lead to lucrative cane-toad farming.

It’s a reasonable claim that the incentives would simply be too low to be effective, leading to no change in the status quo (besides large freezers sitting empty at local council buildings).

Yet even as a toothless policy, a cash-for-cane-toads scheme could produce other unintended consequences.

When people already do something out of their own goodness, like volunteering, putting a price on the activity by offering chump change can actually put them off. Behavioural economists call this “crowding out of intrinsic motivation”. It explains why blood donation rates are no different between countries that pay donors (such as the United States) and those that rely on volunteers (such as Australia).

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One of the best-known examples in economics involved a day-care in Israel that introduced small fines for parents who were late picking up their children. The result was a doubling of lateness. Before the fine, parents would try to come on time because it was the right thing to do. After the fine, however, that moral value had a price: about three dollars.

Notably, parents continued to come late after the fines were removed. Parents who pay pocket money for chores need only imagine how their own kids would respond if they moved to a “volunteer system”.

Thus economics gives us a third reason to doubt Senator Hanson’s proposal will work: the risk that altruistic citizens who have culled cane toads for free will be discouraged by a price being put on the activity.

Instead of considering the “priceless” value of native ecosystems when spotting an offending creature, people may start weighing up their efforts against 10 cents. This cost-benefit thinking could continue even after the compensation scheme ends.

The cane toad is the world’s largest toad. An adult’s body is typically 10-15 cm in length, but some grow at large as 24 cm.
http://www.shutterstock.com

That’s the crux of why this payment scheme wouldn’t work. Setting a high price perverts the incentives, while setting a low price crowds out intrinsic motivations. In either case, taxpayer money is wasted and the toad problem is potentially made worse.

The best approach is to leave prices out of it and trust our experts, who are continuing to come up with remarkably innovative ideas to solve the cane toad problem.

Senator Hanson’s proposal was no doubt made with the best of intentions. Unfortunately, in reality the only real beneficiaries would be economics teachers.

David Smerdon, Assistant Professor, School of Economics, The University of Queensland

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

We’ve cracked the cane toad genome, and that could help put the brakes on its invasion

Cane toads are on the march, but new genetic research could slow them down.
Michael Linnenbach

Peter White, UNSW; Alice Russo, UNSW, and Rick Shine, University of Sydney

We and our international colleagues have deciphered the genetic code of the cane toad. The complete sequence, published today in the journal GigaScience, will help us understand how the toad can quickly evolve to adapt to new environments, how its infamous toxin works, and hopefully give us new options for halting this invader’s march across Australia.

Since its introduction into Queensland in 1935, the cane toad has spread widely and now occupies more than 1.2 million square kilometres of Australia. It is fatally poisonous to predators such as the northern quoll, freshwater crocodiles, and several species of native lizards and snakes.

Previous attempts to sequence the cane toad, by WA researchers more than 10 years ago, were not successful, largely because the existing technology could not assemble the genetic pieces to create a genome. But thanks to new methods, we have succeeded in piecing together the entire genetic sequence.

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Read more:
Yes, you heard right: more cane toads really can help us fight cane toads

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Our team, which also featured researchers from Portugal and Brazil, worked at the Ramaciotti Centre for Genomics at UNSW. This centre played a key role in decoding the genomes of other iconic Australian species, including the koala.

Sequencing, assembling and annotating a genome (working out which genes go where) is a complicated process. The cane toad genome is similar in size to that of humans, at roughly 3 billion DNA “letters”. By using cutting-edge technology, our team sequenced more than 360 billion letters of cane toad DNA code, and then assembled these overlapping pieces to produce one of the best-quality amphibian genomes to date.

We deduced more than 90% of the cane toad’s genes using technology that can sequence very long pieces of DNA. This made the task of putting together the genome jigsaw much easier.

Toxic toads

The cane toad has iconic status in Australia, with many Aussies loving to hate the poisonous invasive amphibian. This is a little unfair. It’s not the cane toad’s fault – it was humans who chose to bring it to Australia.

Our obsession with sugar in the 1800s led to the toad’s introduction to many countries around the world. Wherever sugar cane was planted, the cane toad followed, taken from plantation to plantation by landowners as the warty interlopers travelled from South America to the Caribbean and then on to Hawaii and Australia.

But unlike most other places to which the cane toad was introduced, Australia lacks any native toads of its own. The cane toad’s powerful poisons are deadly to native species that have never before encountered this amphibian’s arsenal.

The cane toad has therefore been subject to detailed evolutionary and ecological research in Australia, revealing not only its impact but also its amazing capacity for rapid evolution. Within 83 years of its introduction, cane toads in Australia have evolved a wide range of modifications that affect their body shape, physiology and behaviour.

For example, cane toads at the invasion front are longer-legged and bolder than those in long-colonised areas and invest less into their immune defences (for a summary, see Cane Toad Wars by Rick Shine).

The new genome will give us insights into how evolution transformed a sedentary amphibian into a formidable invasion machine. And it could give us new weapons to help stop, or at least slow, this invasion.

Cracking the cane toad genome.

Viral control

Current measures such as physical removal have not been successful in preventing cane toads from spreading, so fresh approaches are needed. One option may be to use a virus to help control the toad population.

Viruses such as myxomatosis have been successfully used to control rabbits. But the cane toad viruses studied so far are also infectious to native frogs. The new genome could potentially help scientists hunt for viruses that attack only toads.

In a study published this month, we and other colleagues describe how we sampled genetic sequences from cane toads from different Australian locations, and found three viruses that are genetically similar to viruses that infect frogs, reptiles and fish. These viruses could potentially be used as biocontrol agents, although only after comprehensive testing to check that they pose no danger to any other native species.

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Come hither… how imitating mating males could cut cane toad numbers

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The full cane toad genome will help to accelerate this kind of research, as well as research on the toads’ evolution and its interactions with the wider ecosystem. The published sequence is freely available for anyone to use in their studies. It is one of very few amphibian genomes sequenced so far, so this is also great news for amphibian biologists in general.

As the cane toads continue their march across the Australian landscape, this milestone piece of research should help us put a few more roadblocks in their path.

Peter White, Professor in Microbiology and Molecular Biology, UNSW; Alice Russo, PhD candidate, UNSW, and Rick Shine, Professor in Evolutionary Biology, University of Sydney

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

Yes, you heard right: more cane toads really can help us fight cane toads

Rick Shine, University of Sydney

Eighty years ago, an agricultural scientist named Reginald Mungomery brought cane toads to Australia, bred them, and released their offspring in sugar cane plantations near Cairns. Little did he know that he was setting in train one of the greatest ecological disasters to befall Australian wildlife. His decision has been universally condemned since.

But now, almost a century later, I am proposing that we can fix Mungomery’s historic blunder by doing almost exactly what he did. Ironically, we can buffer the devastating impact of the cane toad invasion by releasing juvenile toads at the invasion front.

This idea might sound ludicrous. The idea of releasing even more cane toads sounds like the height of academic folly. But it works, and my colleagues and I have even managed to convince initially sceptical management authorities and private landowners to adopt the method.

Our key discovery was that populations of most species of native predators aren’t affected by the toad invasion. A few individuals are fatally poisoned when they eat a toxic toad, but most predators aren’t killed by such a meal. If the toad it eats is fairly small (and thus not too poisonous), the predator becomes ill, and learns not to eat toads in future. After that learning experience, the predator can coexist indefinitely with cane toads – it doesn’t try to eat them, so it’s not at risk.

So why doesn’t this same kind of learning save the larger predators – such as quolls, goannas, bluetongue skinks and snakes – that die in droves as soon as cane toads arrive in an area? Our surveys show up to 95% mortality in these species.

The reason is that these large predators attack large toads, and these toads contain more than enough poison to kill even a massive goanna within minutes.

Sadly, the apex predators never get an opportunity to encounter the smaller toads that could have offered them a lifeline by teaching them to steer well clear.

On the frontline

The invasion vanguard is dominated by large adult toads, of a size that kills rather than educates any predator who eats it. Smaller toads (and reproductive females, heavy with eggs) aren’t at the frontline because they can’t keep up with the fastest invaders. As a result, cane toads don’t usually breed until a year or two after the first wave arrives – and by the time the area contains small as well as large toads, the predators have already been killed.

Size matters when it comes to cane toads.

So native predators face a stark equation. If the first cane toad you meet is a large one, you die. If the first cane toad you meet is a small one, you learn not to eat toads, and you survive.

This suggests a straightforward way to buffer the ecological impact of the cane toad invasion: ensure that the predator’s first meeting is with a small toad rather than a large one. There’s a very easy way to do this: we can release small toads at the invasion front, or induce aversion by other methods (such as feeding native animals toad-flavoured sausages).

Getting results

We have trialled this method, and it works. Three of the most vulnerable species – Northern Quolls, Bluetongue Skinks, and Yellow-spotted Goannas – all survive toad invasion if they are trained beforehand, but die if they are not.

For example, my research colleague Georgia Ward-Fear captured goannas on a Kimberley floodplain, radio-tracked them, and dangled small cane toads in front of some of the lizards. Many of them seized on the toad, became nauseous, and avoided toads afterwards. Of the goannas that Georgia trained in this way, half were still alive at the conclusion of her study 18 months later – whereas all of the untrained lizards died long before then.

But isn’t this just a stopgap solution, delaying the wave of predator deaths for just a single generation? Won’t the offspring of those trained predators need to be trained as well, and so on forever? No, they won’t.

Within a year or two of the toads’ arrival in an area, they begin to breed – and so the offspring of our trained predators grow up in a world with small as well as large cane toads. The young predators will encounter small toads, eat them, and learn to give them a wide berth. All we need is a single generation of education to provide a long-lasting benefit.

We are now working with Western Australia’s Department of Parks and Wildlife to fine-tune our methods, and then implement them on a landscape scale. We can’t stop the toad invasion from proceeding through the Kimberley, but we can substantially blunt the invaders’ impact. Ironically, the way we are doing it is almost exactly the same as the act that caused the problem in the first place, when Reginald Mungomery released those first young cane toads in cane fields on the other side of the continent.

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Rick Shine is the recipient of the 2016 Prime Minister’s Prize for Science for his work on the cane toad problem.

Rick Shine, Professor in Evolutionary Biology, University of Sydney

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

Teaching reptiles to avoid cane toads earns top honour in PM’s science prizes

Michael Hopkin, The Conversation

A conservation biologist who is bidding to help Australia’s native animals learn to give cane toads a wide berth has been awarded the 2016 Prime Minister’s Prize for Science.

University of Sydney professor Rick Shine was given the award for his work in using evolutionary principles to boost the effectiveness of real-world conservation.

One example is his innovative use of “teacher toads” – small cane toads deployed in areas where native animals are threatened by the poisonous invaders. These small toads aren’t big enough to kill but are unpleasant enough to encourage animals such as quolls and lizards to steer clear of eating bigger cane toads in future.

Invading cane toads are spreading westwards across tropical Australia and have now reached the northern parts of Western Australia, growing bigger and faster as they go. By deliberately releasing smaller cane toads ahead of the invasion front, the project aims to give native animals a better chance of avoiding being caught on the hop.

Professor Shine’s research has also explored ways to stop cane toads reproducing, by lacing traps with pheromones from other species that attract cane toad tadpoles.

Originally a reptile biologist, Professor Shine began studying cane toads after one arrived at a site on the Adelaide River near Darwin, making him realise the significance of the threat the toads posed.

“The creatures like snakes and lizards that dominate our ecosystems, they’re the ones we have to focus on, they’re the ones we need to understand if we want to keep Australia’s ecosystems functioning,” he said.

Rick Shine on his love of reptiles.

UNSW Australia conservation ecologist Mike Letnic said that Professor Shine has been a role model for many scientists, particularly biologists tackling big questions about evolution and conservation.

“For me the biggest contribution he has made is in studying the rapid evolution of some species such as snakes, and obviously the work on cane toads feeds into that. The big challenge is whether you can harness that evolution for biological control,” he said.

“With cane toads it is not just the selection process but also the spatial sorting – faster, fitter toads are skewing selection by being at the invasion front.”

Cash and plastic

Other award recipients include Michael Aitken of the Capital Markets Cooperative Research Centre, who won the Prime Minister’s Prize for Innovation for his use of financial data to identify ways to improve Australia’s health markets.

Having initially developed ways to detect fraud in financial markets, Professor Aitken then turned his attention to spotting inefficiencies in health spending.

He and his colleagues have identified examples of “low-value treatments”, which are over-prescribed relative to the benefits they deliver – such as prostate screening and surgeries for chronic arthritis.

“We are looking at maybe A$20 billion per year that could be directed to improve health care in areas of genuine want,” he said. “These might be treatments that are of no great benefit. But surgeons are paid to do surgery – and if they don’t do surgery they don’t get paid, so they do it.”

Professor Aitken said you can learn a lot by studying the “low-hanging fruit” of health financial data to spot treatments that are being over-prescribed. But he then asks clinical experts to evaluate the evidence base for the treatments themselves.

Michael Aitken explains his data-driven approach.

Another scientist being honoured for innovation is Colin Hall of the University of South Australia, who has created a high-tech, all-plastic replacement for standard car wing mirrors.

His design is lighter and more sustainable than the conventional metal-and-glass design, but it had to pass a succession of stringent tests designed to mimic harsh motoring conditions before being adopted by the car industry.

“The hardest was the salt test – it had to be sprayed with very salty hot water for ten days,” Hall said.

Other tests included a thermal shock test in which the mirrors had to cycle rapidly between -40℃ and 80℃, 200 times in a row, to ensure they could handle temperature changes.

Colin Hall’s high-tech plastics have passed the test.
Prime Minister’s Prizes for Science/WildBear

Hall’s earlier research focused on designing high-tech plastics for spectacles. But while a pair of glasses might be replaced within a year, cars are designed to last at least a decade, which means the industry is very strict about which designs it approves.

Hall hopes that, in time, all of the metal components on cars can be replaced with plastic alternatives, thereby doing away with the highly polluting electroplating processes currently used in car production.

Peptides, proteins and ecosystems

Other prizewinners include Richard Payne of the University of Sydney, whose work on re-engineering protein molecules found in nature promises to give us new ways to treat stroke, malaria, tuberculosis and even cancer, and has earned him the Malcolm McIntosh Prize for Physical Scientist of the Year.

University of Queensland conservation scientist Kerrie Wilson has won the Frank Fenner Prize for Life Scientist of the Year, for her work on evaluating “ecosystem services” – the benefits provided by natural resources such as clean air, water and food.

Perth teacher and former geoscientist Suzy Urbaniak has won the prize for excellence in secondary school science teaching, while the award for primary school science education went to Sydney-based Gary Tilley.

The winners, who will share a prize pool of A$750,000, will receive their prizes from Prime Minister Malcolm Turnbull and Science Minister Greg Hunt at a dinner in Parliament House this evening.

Michael Hopkin, Environment + Energy Editor, The Conversation

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

Australia: NSW – Cane Toads Media Release

The link below is to a media release concerning Cane Toads in NSW and it contains some very good news.

For more visit:
http://www.environment.nsw.gov.au/media/OEHMedia14041501.htm

Crimson Spotted Rainbow Fish: Avoiding the Toad

The link below is to an interesting article concerning the Crimson Spotted Rainbow Fish and the dreaded Cane Toad.

For more visit:
http://www.australiangeographic.com.au/journal/native-fish-outsmart-cane-toads-.htm