In January 2023, on another sunny Australian day at the Pacific Harbor golf estate, groups of eager players marched along the course, only to find the grass littered with thousands of small black creatures. Upon inspection, the golfers realized that these little things were actually baby cane toads, over 2,700 of them, on one golf course alone!
But these amphibians aren’t native to Australia; they’re from the Americas, half the world away! But how did they get there? Why are there so many? Let's dive into a story of humanity’s attempts to control nature and the grave consequences that followed.
Cane Toads VS Cane Beetles
Let’s go way back to the 1860s, when farmers across Queensland were growing one of Australia’s major exports: sugar cane, a tall grass from which we get sugar! However, in the 1880s, these farmers faced a small, grubby problem: the cane beetle.
These are a group of insect species that feast on the leaves of the cane. What’s worse is their offspring: the larvae of Greyback and Frenchi Cane beetles hatch underground and gnaw away at the cane’s roots, stunting or killing the plants entirely.
One 2011 report from Crop Life estimated that without today’s insecticides, the annual loss of sugarcane would be around 600,000 tons, that’s the equivalent of twenty Statues of Liberty. The problem became so severe that, in 1900, the Queensland government established the Queensland Bureau of Sugar Experiment Stations, or the BSES for short. For around 25 years, entomologists, scientists who study insects, examined the cane beetle’s life cycle, biology, and more, to find the best solution to the problem. Various ideas were proposed, such as insecticides, though these measures were usually deemed too expensive, not readily available, or they just didn’t work. In 1932, at the World Congress of Sugar Technologists in Puerto Rico, Raquel Dexter praised the effect of a particular animal species in controlling beetle numbers in Hawaii, the Philippines, and Puerto Rico. This animal was the cane toad, and the BSES leapt on the idea.
What exactly is a
cane toad? Originally, their natural range spanned from the rainforests of the Amazon basin to the arid deserts of southern USA. On the animal survivability scale, these guys are on rat level. They can eat up anything from insects, birds, lizards, and small mammals, to pet food, garbage, and poo.
The only limit to a toad’s appetite is the size of its mouth. Luckily, there’s no reports of them devouring humans yet. They can live in nearly any habitat, be it tropical forests, urban neighborhoods, savannahs, or grassy plains. Cane toads live for about 5 years in the wild and measure 6 to 9 inches in length, which is about the same as a fork. However, you don’t want to eat these fellas! The toad is deadly from the moment its egg is hatched. Their spawn release poison into waterways, killing fish, and a tadpole’s toxin runs throughout their body, making it lethal to any animal that eats it. Cane toads are prolific breeders, with females able to lay a string of 35,000 eggs at a time. On an adult toad, you can spot sacks on top of their shoulders. These are
parotoid glands, which secrete a milky white toxin called bufotoxin, which they use to defend against predators. Under pressure, a toad can shoot toxin up to 3 feet away. This stuff is seriously dangerous; if ingested, it can cause convulsions, paralysis, and, in some cases, death has occurred in just 15 minutes.
The question is, why did those BSES guys think that introducing a toad that poisonous was a good idea? Well, the introduction of cane toads was supported by a peer-reviewed scientific paper, the scientific organization CSIRO, the Queensland government, the Commonwealth government, the prime minister, and met quarantine regulations!
Basically everyone thought the toads were going to be a surefire hit, especially after the successful introduction of the cactus moth in 1926. This cactus eating species was brought over to
tackle the spread of prickly pear cactus, which had taken over 60 million acres of land in New South Wales and Queensland. By 1933, prickly pear populations in Queensland had reduced by 80% and convinced Australians that biological control was the way to go.
In June 1935, BSES sent their entomologist, Reginald Mungomery, to Hawaii. Like everyone else, Mungomery was convinced that the introduction of toads would be effective. He managed to capture 102 cane toads, 51 females and 51 males, and then sailed back to Australia with them packed in two crates. Upon arriving in the land down under, the toads were dehydrated, with one male perishing along the way. Undeterred, Mungomery brought the remaining ones to Meringa Experimental Farm, one of BSES’s outposts just outside Gordonvale, Queensland. There, he had a gazebo enclosure set up for the toads to breed. Despite their tiring journey, these things certainly got busy. By August 1935, the 101 toads had ballooned to 2,400, all of which Mungomery released into the wild.
However, there were a few people in those days against the proposal. In December 1935, concerns from entomologist Walter Froggatt led to a ban on the release of any more toads. Froggatt predicted ‘…this great toad, immune from enemies, omnivorous in its habits, and breeding all year round, may become as great a pest as the rabbit or cactus.’ Sadly for Walter, his ban didn’t last long. Froggatt’s toad-loving peers decried him for being "decidedly pessimistic" and holding "an incurable bias." In September 1936, after lobbying by the Queensland Premier, the Minister for Agriculture, the BSES, and cane farmers, Prime Minister Joseph Lyons gave in to the pressure and lifted the ban. Lyons' decision led to the importation of cane toads with little to no checks or control measures in place. The biggest problem was that nobody had bothered to check if, once bought to Australia, the toads actually ate cane beetles.
Biological Control Gone Wrong
So, was cane toad introduction effective? No. The beetles live on the upper branches of sugarcane plants, which the toads can’t climb, so opportunities for toads to prey on the beetles are slim. Greyback beetles only briefly descend to the ground to lay their eggs. While Frenchi beetles are only on the ground when there is no cover, and cane toads avoid cane fields during these periods. Consequently, there are few instances where both animals are together at the same place at the same time.
Analysis by biologist Rick Shine found that in the years when toads were released in the cane-fields, there was no increase in yields. As mentioned earlier, toads are incredibly toxic and will poison native predators that do eat the beetles, like the yellow spotted monitor, increasing beetle populations. To add insult to injury, in 1945, the pesticide Gammaxene was successfully tested, and cane farmers used this to handle the beetles and grubs, though by then the damage was already done. It’s safe to say that the BSES’s checks could have been a bit more thorough. Scientists working on the project were experts in their field, they weren’t dumb. The problem was that, at the time, the BSES, scientists, government officials, everyone, got swept up in this toady mania that made it impossible for someone with concerns, like Froggatt, to have their voices heard. Mungomery’s gung-ho attitude to invasive species wasn’t surprising. In colonial Australia, Acclimatization Societies set about bringing flora and fauna from Europe, with no regard to what effect it’d have on native species. This attitude stretches back to Australia’s very inception in 1788, when
the First Fleet, a group of 11 ships carrying settlers, convicts, and officers, arrived from England to Sydney Cove. These settlers, and ones that followed, would bring flora and fauna for work, food, and to combat homesickness.
In 1859, English settler Thomas Austin, introduced rabbits to his estate, Barwon Park, importing 13 from the village of Baltonsborough in Somerset, England. There is an estimated 200 million feral rabbits in Australia, overgrazing on native plants and crops. Every rabbit’s ancestry can be traced back to that one warren in Baltonsborough. Likewise, feral cats are one of the biggest contributors to Australia’s wildlife loss. Ever since they were bought over by the First Fleet, cats have gone onto inhabit 99.9% of Australia’s landmass, including alpine regions, deserts, coasts, and over 100 islands. Every year, an individual feral cat kills approximately 390 mammals, 225 reptiles, and 130 birds. Collectively, they are responsible for the
deaths of 1.4 billion Australian animals a year. That’s a whole lot of dead things lying on the doorstep.
By the 20th century, ideas regarding ecology were improving, with people being more scientifically minded in their approaches. But as we have learned from the toads, the colonial belief that Australia’s habitat could be improved still existed in the 1930s. Since the release of 2,400 toads by Mungomery, their population has increased to over 200 million today!
Ever since then, the range of cane toads has grown across the north of Australia and they continually move westward at an estimated 25 to 40 miles per year. In 2022, 17 toads were spotted as far down as Mandalong, a rural town only an hour away from Sydney. Their success is partly down to their toxin, since the toad has no natural predators to keep its numbers in check. In the toad’s natural range, 30,000 eggs typically produce just 1.5 surviving toads. In Australia, this number is closer to 150, it’s no wonder that we have mountains of them! The amphibian’s conquest has led to the decline of native species, like the northern quoll, a cute marsupial, once common throughout north Australia. In Queensland, cane toads have resulted in a
75% decline in quoll populations. A study back in 2004 found that cane toads had destroyed about a third of the ground nests of bee-eater birds by moving in, eating their eggs, and their chicks. These things have even taken on Australia’s nastiest carnivores: the freshwater crocodile. Since 2005, the toad has wiped out 77% of these ruthless reptiles. Removing an apex predator from its ecosystem can increase the numbers of prey animals leading to untold consequences on the environment.
While it's pretty unusual for people to get poisoned by bufotoxin, the same is not so true for our four-legged friends. Dogs will often mouth, lick, and bite toads,
subjecting themselves to the deadly toxin. The poison is absorbed through the gums and tongue with shocking speed as it begins to attack the nervous system. Thousands of dogs are poisoned every year, with puppies and smaller breeds like terriers being the most affected because they find the toad's jumpy movements irresistible. However, a few predators have been fighting back. For instance, crows have been found flipping the toads over and tucking into their juicy thighs, tongue, and intestines while avoiding their lethal glands altogether. Another brainy bird, the Australian white ibis, also known as the bin chicken due to its love of trash, has found an ingenious way of chowing down toads. Ibis squeeze the toad in their beaks, getting them to release their toxins, then they wash them in river water, before eating them. Birds aren’t the only ones in on the action. The keelback snake can consume the amphibian without being affected by their toxin at all! Their immunity may be due to its recent ancestry in Asia, where prey with defensive toxins are more common.
Prey - Buff Striped Keelback Eating Toad || Non-venomous Snake || Food Chain || STS Mundgod by Wanderlust_KG Invasive Species & Evolutionary Change
Of course, it’s not just the cane toads affecting Australia; Australia has affected the cane toads too. Despite their wild origins, these amphibians have developed a taste for urban environments, where garbage is in rich supply. To the relief of all you Aussies living among them, urban toads are less poisonous than their rural counterparts, probably due to the lack of predators.
What’s even odder is how city environments have changed toad physiology, especially between the sexes: the leg bones of urban males are longer than those of rural males, while for females, it's the opposite. This could be because urban males need to move quickly to navigate barriers, like roads. If you thought that adults were the only ones going through changes, you were wrong. Tadpoles, when exposed to the toxin in their eggs, develop an insatiable appetite, leading them to eat the eggs of both native toads and
their own species.
This bizarre behavior has only been observed in Australian cane toads in recent decades. Tadpoles might do this in order to drive down rival toad populations. Since cane toads don’t need to compete with other animals to survive, they end up competing with each other. Being free to breed and grow as much as they like, these things can reach incredible sizes. In January 2023, ranger Kylee Gray was strolling through Queensland’s Conway National Park when she stopped to let a snake slither past. Then she noticed something else, it was a toad, the largest toad she’d ever seen! The female weighed 6 lbs, which is bigger than a Chihuahua! It was so large it might hold the record for the biggest toad ever recorded, surpassing the previous record held by another cane toad from Sweden, which weighed only 5.8 lbs. Once discovered, she was promptly removed from the park and recorded, with the
media dubbing her Toadzilla.
'Toadzilla': massive 2.7kg cane toad found in Queensland, Australia by Guardian Australia There may have been a reason for Toadzilla’s gut busting girth. A 2013 study found that as cane toads spread across Australia, the ones leading the charge get first dibs on prey and face less competition. This all results in higher feeding rates, larger fatter bodies, and faster growth than those who follow in their wake. Humans have been pretty powerless in trying to hold back this horde. The full impact of toads on the environment weren’t known until 1975, nearly 40 years after their release. A survey was conducted by Mike Archer and Jeanette Covacevich from the Queensland Museum, where the pair revealed the animal’s failure to eat beetles, their spread, and the startling threat they posed to native wildlife. In 2005, the government launched the Threat Abatement Plan, which attempted to study, monitor, and control the toad invasion. Early research found that in Venezuela, viruses help keep the cane toad population in check. Annoyingly, lab tests revealed that the same viruses also harmed native Australian frogs. To protect Northern Quolls, about 60 were relocated to the toad-free Astell and Pobasso islands. Additionally, local governments tried teaching people across New South Wales and the Northern Territory about the dangers posed by these oncoming beasts!We all know the old saying: if you can’t beat it, make a bag out of it! That’s exactly what fashion outlet Vermin the Label is doing. Led by Lia Tabrah and Perina Drummond, this brand transforms warty toad skins into leather, which they use to create stylish accessories like handbags and wallets.
Cane Toad Sausages & Leather
Drummond, who’s from the Torres Strait Islands, witnessed firsthand the destruction these toads can cause. So, she set up her own sustainable tannery where the toads are caught, skinned, and dyed, ready for making products. But it's not just about helping the environment; Vermin also hire local people from the Torres Strait community to catch the toads. Bored kids can even get involved and earn some allowance. Coming from a toad, you'd have thought that this material would be covered in lumps and slime. But Drummond says that toad leather is actually soft and smooth.
When it comes to solutions, Vermin aren’t the only ones getting creative. In 2015, Professor Shine decided to help the declining number of northern quolls in the Kimberley region with a brilliant plan: sangas! That’s Australian for sausages! Kimberely was predicted to be overcome with a wave of toads, so the Australian Wildlife Conservancy organized helicopters to rain down cane toad sausages across the northwest, as well as having scientists on foot spread them too. The warty wurst is made from minced cane toad legs laced with nauseous chemicals.
When quolls find these sausages and eat them, it makes the animals sick, but don’t worry, they’re not lethal. Seems like an odd way to save a species, but, ingeniously, Shine hoped that by doing this ahead of the invasion, these animals would be put off toad meat and learn to avoid them when hunting!
However, in 2023, it was found that
the program had hit a snag. The success of this experiment has been mixed, with research showing that some quolls, even after eating the contaminated sausages, will return to a toad diet after 120 days. Quolls at the Artesian Wildlife Sanctuary don’t even eat the baits. Kimberley has now been infiltrated by a wave of toads, so it’s too late to carry on these taste aversion experiments. While the plan may not have gone well for the mammals, for the reptiles things are looking hopeful! Scientists are trying to train yellow spotted monitors and crocodiles to avoid eating toads by feeding them contaminated carcasses, since they aren’t that keen on sausages. Monitors can even be put off by devouring juvenile toads, which will make them sick enough to deter them from eating the adults. Even so, it seems that these toads keep outwitting us humans at every turn. As of 2023, there is no widescale control for this unstoppable mob with the government unable to come up with a widespread measure, instead giving advice on how to deal with individual toads. Citizens are encouraged to use fencing to stop them laying toad spawn in ponds and removing eggs from water.
Cane Toad Fences by fred If you really want to go Terminator on these little things, the government recommends putting them in the fridge for an hour and then the freezer overnight. Some community groups have even taken measures into their own hands, going out to capture and kill cane toads by putting them in bags filled with carbon dioxide. Some people just straight up run them over, though you’d struggle to get them all.
However, not everyone hates these intruders. Bufotenine is an ingredient found in the toxin of a cane toad, which possesses hallucinogenic properties. Some people have taken to harvesting this toxin for some groovy uses. However, it’s not recommended because of pain and death.
Invasive Asian Carps
We shouldn’t just be yelling at Australia; America has ruined the planet too! In the 1970s, Asian carp were introduced to control algae and parasites in fisheries, as well as to provide a cheap fast-food product. But alas, these fish farms flooded, the carp escaped, and soon spread into natural waterways, establishing themselves in 45 states. They eat 5 to 20 percent of their body weight per day on plankton, outcompeting native fish species which are also dependent on this food source.
Carp can weigh up to 110 pounds, that’s heavier than a toilet, so there’s few predators big enough to prey on them. There are four species of Asian carp: bighead carp, black carp, grass carp, and silver carp, which as you might’ve guessed, all come from Asia. Silver carp are particularly jumpy, literally! If they’re disturbed by a loud noise, like the roar of a boat’s motor, a whole school will leap up to 10 feet in the air in a fishy frenzy. Silver carp can pack a serious wallop if they strike, with there being recorded instances of them breaking bones of people they’ve landed on.
World's Funniest Weather - Fishing Fail - Guy Gets Slapped By Flying Carp! by The World's Funniest Weather Since 2015, the U.S. Fish and Wildlife Service in the Southeast has conducted research and provided funding to better understand and control carp populations. As of 2023, there's a plan to spend nearly $1.2 billion on the Brandon Road Lock and Dam on the Des Plaines River to keep carp from getting into Lake Michigan. The new barrier will use sound, electricity, and a bubble curtain, basically, a wall of bubbles, to stop the carp. If these carp manage to get through, they could seriously impact native species important to the fishing industry, like lake trout.
On a much smaller scale, electrofishing has been used to catch them. This is when fishermen submerge two electrodes into the water, releasing a current that stuns the fish, rendering them motionless. The fish then rise to the surface, where they can be easily caught.
Invasive Species Aren't Always Bad
Are all invasive species bad then? Not necessarily. Dr Mark Davis, along with other scientists, argue that certain non-native species can be beneficial to their introduced environments. In California, the native monarch butterfly spends winters in the branches of the eucalyptus, a non-native invasive tree introduced to the state over 150 years ago. Bank voles were accidentally bought over to Ireland in the 1920s, probably from Britain. The species has naturalized now, becoming a crucial food source for native predators.
Davis highlights the flawed perception of non-native species in mainstream science and media. He argues that efforts to eradicate these species are often pointless and detrimental. As we’ve seen, attempts to control species like cane toads have proven nearly impossible. Climate change is already pushing native species out of their habitats, complicating the distinction between native and non-native. These scientists advocate for a more nuanced approach to managing non-native species. For them, what constitutes an invasive species is often arbitrary and based on emotions, rather than data. This is obvious in the case of the beavers, which were reintroduced to the UK in 2002, after being hunted to extinction 400 years ago. These creatures are totally excellent for a number of reasons, they create wetlands that benefit a variety of species and their dams help reduce flood flows by 60%, protecting communities living downstream. But, despite being native to the UK, beavers are still vilified and billed as an alien species in a lot of circles.
Invasive Species Damage
Davis’s position on non-native species is controversial amongst scientists. It’s not surprising, invasive species costs the world economy more than $423 billion every year by damaging native ecosystems, food sources, and threatening human health.
Over the years, humans have intentionally and unintentionally introduced more than 37,000 species to places outside their natural ranges. More than 3,500 of these species damage their new ecosystems. Climate change has led to warmer climates in Europe, opening the floodgates for tiger mosquitoes to spread dengue fever and the Zika virus. Over the past two decades their numbers have increased leading to mass outbreaks across Western Europe.
Out of all the countries in the world, none have been affected worse than Australia. Action to fix the damage done by invasive species
costs their economy $25 billion dollars every single year, that’s $16.6 billion in US dollars. Once Australia had around 600,000 species of plants and animals. Today, around 100 of them have become extinct in the last 200 years and over 1,770 are currently listed as threatened or endangered. Australia’s farming is also in trouble, with invasive animals impacting food production through predation on livestock, chomping on crops, and the spread of diseases. Unfortunately, we're not close to finding a solution.
