Australia Releases Cats Onto Island To Kill Rats - WHAT HAPPENED NEXT WAS EVEN WORSE

[00:00:00]In the winter of 2010, helicopters flew continuously across Mcquaryy Island.

[00:00:05]Suspended beneath each aircraft was a large metal hopper filled with millions of serial bait pellets laced with bratafakum and extremely toxic anti-coagulant poison. As the hopper spun, millions of pellets scattered across the mountain slopes, valleys, rocky beaches, and nearly every part of the island. They were not trying to destroy life on the island. The operation had been ordered by the authorities to save one of the most important seabird sanctuaries in the southern ocean. The pilots and environmental crews tried to make use of every available moment, but strong winds, low clouds, and weather that could change within minutes repeatedly forced the helicopters to remain on the ground. The campaign had to be suspended after less than 8% of the planned bait had been distributed across the island.

[00:00:50]Even so, native birds began dying one after another from both direct and secondary poisoning. Over 6 months, recovery teams collected 960 bird carcasses, and the actual number may have been even higher because many bodies were never found. One year later, Melissa Hton arrived on that same island with Wags, a black Labrador. Their job sounded simple, but it was almost impossible. Find every last survivor. It took 204 years, 24.6 million Australian dollars, and a Labrador named Wags to undo what had happened. This became the most successful invasive species eradication project in Australian history, completely removing the targeted invasive animals. But this story is not being told to glorify anyone. Every detail has been verified using reports from Australia's Department of the Environment, biological research published in Nature, and records from the Tasmania Parks and Wildlife Service. On a map, McCquory Island is little more than a tiny dot between Tasmania and Antarctica. The island is about 34 km long, but when the first explorers arrived, they found a place unlike anywhere else on Earth.

[00:02:00]Elephant seals covered the beaches.

[00:02:03]Royal penguins gathered in enormous colonies. And the interior was filled with tusk grasslands and herbaceious plants that grew taller than a person.

[00:02:12]In 1810, the first ceiling ships reached McQuary Island. Within 10 years, the first seals had been wiped out, followed by elephant seals and millions of penguins. But that was not the worst of it. Black rats and house mice hid aboard the ships and came ashore with humans, beginning a disaster that would last for more than two centuries. To be honest, it was not difficult for them to become some of the island's most dangerous invaders. Mcquaryi Island seabirds had evolved for generations without land-based predators. Scientists call this predator naivity. Rats entered petrol burrows, ate eggs, chicks, and insects, and also raided food stores at the ceiling camps. To deal with the problem, people brought cats to the island. It seemed like a reasonable decision, but it was the wrong one. The cats quickly switched to easier prey. By the 1970s, an estimated 500 feral cats were killing 60,000 seabirds every year.

[00:03:06]That is more than 160 birds a day. Not occasionally, but every single day, year after year. People continued introducing more animals to Mcquary Island. In 1867, the wcka, a flightless bird from New Zealand, was brought there as a food source. You can probably guess what happened next. The WA did not survive on human food alone. They ate eggs, chicks, and small native animals, placing even more pressure on an ecosystem already under attack from cats and rats. In the late 1870s, European rabbits were introduced to provide meat for the oil processing crews, and yes, they thrived.

[00:03:44]The rabbits spread from the valleys to the slopes and high plateaus, eating vegetation, damaging roots, and destabilizing the soil. By 1968, their population had reached 100,000. Each time a new species was brought to the island, the decision seemed reasonable at the time. Rats arrived by accident.

[00:04:03]Cats were introduced to control the rats. Wcka were brought in as food for people. Rabbits were introduced to help keep people alive. No one was deliberately trying to destroy the island. When considered separately, each decision made sense, but no one could see the entire chain of consequences.

[00:04:20]Every intervention led to another intervention. Every solution created a new problem. At the time, however, the concept used to describe what was happening did not yet exist. Only later would scientists give it a name. As in so many stories, after humans had damaged the ecosystem, biologists began searching for ways to save it. Australia decided that simply controlling the invasive animals was not enough. They had to be completely removed from Mcquaryy Island. The program began in 1974 and was later expanded into a dedicated eradication campaign in the late 1990s. Hunting teams used cage traps, firearms, and leg hold traps to track down the last remaining animals.

[00:05:03]Between 1,996 in 2002, they recorded 761 cats captured or killed, more than 6,000 days of field work, and over 216,000 trap nights. In June 2000, the last known cat was removed. After that, petrols began returning, but McQuary Island had not truly been saved. This solution was only temporary, and it created an even bigger problem. Cats did not prey only on seabirds. They also ate young rabbits, placing some predatory pressure on the rabbit population. So, when the last cat disappeared in 2000, the number of rabbits exploded. Within just 5 years of the cats being removed, the population surged from 100,000 to 300,000. This was not a gradual increase. It was an outbreak so severe that it could be seen from orbit. Hills that had once been lush and green, turned brown. Poa annua, an invasive grass from the northern hemisphere, spread across slopes where native tusk grasses had grown for centuries. One scientist described the phenomenon as golf course syndrome. A diverse living ecosystem had been reduced to a single species of weed.

[00:06:14]There is a children's nursery rhyme called There was an old lady who swallowed a fly. She swallowed a spider to catch the fly, a bird to catch the spider, a cat to catch the bird, a dog to catch the cat, and a horse to catch the dog. Each solution was larger and more dangerous than the problem it was meant to solve. In the end, the old lady died. It is not just a children's song.

[00:06:37]It is a description of a trophic cascade. By 2006, Mcquaryy Island was home to 300,000 rabbits, 36,000 rats, and an estimated 100,000 mice. The damage to the vegetation could be seen from orbit. 40% of the island's plant cover had been eaten away. What remained was a cratered landscape resembling the surface of the moon, stripped of life and collapsing under its own weight.

[00:07:02]Then came the disaster that shocked the world. In September 2006, a massive landslide struck Lucatania Bay, home to one of the island's most important king penguin colonies. More than 500 square meters of hillside, loosened by years of erosion and destruction caused by rabbits, suddenly collapsed, burying hundreds of king penguins alive. It was a heartbreaking moment that appeared in news reports around the world and marked the point of no return. The Australian and Tasmanian governments understood that they could no longer deal with each species separately. In 2007, the two governments jointly committed 24.6 million Australian dollars to one of the most ambitious invasive animal eradication plans ever attempted. They had to remove every invasive animal from the island, not just some of them. And not only the species causing the most serious damage, every rat, mouse, and rabbit had to be eliminated. The first phase focused on rabbits, which were causing the island's largest and most visible problem. In 1968, scientists had tried using a virus called mixoma, reducing the rabbit population to around 20,000. But that was still not enough.

[00:08:13]This time, they used a more dangerous weapon, rabbit calisa virus, also known as rabbit hemorrhagic disease. In February [music] 2011, pieces of carrot carrying the virus were distributed in areas with the highest rabbit populations. The effect was immediate and extremely severe. The virus spread through the rabbit colonies with devastating efficiency, and within just a few months, the population collapsed.

[00:08:37]Next came the attack from the air.

[00:08:39]Helicopters carrying 300 tons of poison bait flew back and forth across the island, dropping bright blue pellets designed to kill both rabbits and rodents. The operation had to be carefully timed for winter when most seabirds had left the island, reducing the risk of accidentally poisoning native species. But dropping poison was still not enough. Thousands of animal carcasses had to be collected by hand to protect scavenging birds from secondary poisoning. Workers spent months recovering the bodies of rabbits and rodents from every part of the island.

[00:09:10]However, the greatest threat still came from the survivors. A single rat or rabbit hiding deep inside a burrow or sheltering on a rocky slope could ruin everything. Even a few survivors could rebuild their populations across the island within several years. That was when the plan's most elite force was deployed. The dogs 12 specially trained detection dogs, including Springer Spananiels, Labradors, and Terriers, were brought to the island with their handlers. These were highly trained specialists capable of detecting the scent of a rodent from hundreds of meters away. This was the final confrontation. Some of the most destructive invasive species against one of the most determined conservation efforts the world had ever seen.

[00:09:52]Allowing thousands of rodents to live alongside penguins on a small island had caused a disaster. At last, humans were trying to repair the damage. The great hunt had begun. The dogs brought to McCory Island in 2011 were about to carry out one of the most important missions in conservation history. They searched for the last surviving rats, mice, and rabbits, the individuals that could destroy all the progress that had been made. Each dog was carefully selected and trained for months before setting foot on the island. They also had to be exceptionally strong and healthy. McCquory Island's brutal weather is famous for its bitterly cold winds, freezing rain, and deep mud capable of swallowing an entire boot. To survive and work under those conditions, the dogs needed thick coats, strong paws, and relentless determination.

[00:10:41]Every day was a battle against both the weather and time. Leading this canine force was a Labrador named Wags, who worked alongside his handler, Melissa Hton. Their job was to search every corner of the island. By the end of the operation, the search teams had traveled more than 90,000 km, the equivalent of walking around the Earth twice. But McQuary Island did not make their mission easy. Towering cliffs, hidden valleys, underground burrows, and dense vegetation made the search feel like looking for a needle in a hay stack the size of a small city. Just one surviving rat, mouse, or rabbit could allow the entire ecosystem to collapse all over again. That was when the dog's extraordinary sense of smell became essential. They could detect rodent droppings that had been there for weeks, pick up the scent of a mouse that had passed through only hours earlier, or follow a rabbit's trail all the way back to its hidden burrow. Day after day, the search teams climbed across rocks, pushed through thick grass, and explored every cave and crevice they could find, following even the faintest trace of scent. The decisive moment came in November 2011. Melissa Hton and Wags, a black Labrador trained to detect rabbits, were searching the island when they came across fresh droppings and signs of gnawing. The dogs immediately focused on a burrow. The hunting team dug down and captured a black female rabbit sitting right beside a petrol.

[00:12:03]Think about the irony. One of the last surviving members of the species that had destroyed Mcquary Island's vegetation for more than 130 years was hiding inside the burrow of one of the very birds that had suffered the consequences. But that was not the end.

[00:12:18]In late November, the search team discovered another nursing female and four young rabbits. They became the last five rabbits ever recorded on the island. In total, 13 survivors were found after the 2011 baiting operation.

[00:12:32]By 2013, the dogs had gone for months without detecting any sign of rats, mice, or rabbits. But no one was ready to declare victory just yet. The island had already taught them too many painful lessons. The moment they had waited more than two centuries for had finally arrived. On the 8th of April 2014, McQuary Island was officially declared free of rats, mice, and rabbits exactly 204 years after the first ceiling ship arrived there. To confirm the result, 12 detection dogs and their handlers searched nearly every valley, rocky cave, and hillside on the island. Only after 2 years without finding any further signs did the authorities finally declare the campaign a success.

[00:13:13]The program later became a reference model for invasive animal eradication projects on other islands. What surprised scientists most was not simply that the rats and rabbits had disappeared, but how quickly nature responded. At first, they believed it would take 30 to 50 years before any clear recovery became visible. But after only about 18 months, seeds that had remained dormant in the soil for decades began to sprout. Tusk grass returned to the barren hillsides, and after just two growing seasons, green vegetation had reappeared across areas that rabbits had once stripped bare. Several orchid species that had previously survived only inside fenced areas also began spreading beyond the barriers because rabbits were no longer eating them as soon as they emerged. 10 years later, the transformation was even more dramatic. Tusket grass had grown so tall that researchers had to clear paths to move through it. Beneath the vegetation, penguins created winding trails as they traveled between their nests and the shoreline. Two orchid species that had once depended on protective fencing appeared in many new areas while the rare plant Herszia Australiana continued to expand its range. Bird populations also recovered rapidly, some increased by around 10% each year. During the 1970s, cats had killed an estimated 11,000 white-headed petrols annually, and only about 15% of nests successfully produced chicks that survived to fledging. Roughly a decade after the eradication campaign, nesting success had risen to nearly 80%. Gray petrols and blue petrols, which had disappeared from the main island in the early 20th century, also returned on their own without any need for humans to reintroduce them. The success of Mcquaryy Island is now serving as a reference for New Zealand's predator-free rockier project. Rockyura, also known as Stewart Island, covers about 175,000 hectares, while Mcquaryi Island covers only 12,785 hectares. In other words, Rockura is nearly 14 times larger. The island is also home to around 400 permanent residents, making the use of poison, traps, and detection dogs far more complicated. The project aims to eliminate three rat species ship rats, Norway rats, and Kior, as well as possums, feral cats, and hedgehogs. If completed, it would become the largest and most complex predator eradication campaign ever carried out on an inhabited island. However, the project is still in the trial stage. In 2025, New Zealand conducted invasive animal eradication trials across approximately 6,500 hectares while also controlling predators throughout nearly 40,000 hectares of forest. Early results showed major declines in rat, feral, cat, and possum numbers. But work across the entire 175,000 hectares has not yet begun. Project managers must also address the risk that poison could affect white-tailed deer, domestic animals, and the activities of local communities. The experience of McCquory Island also shows that conservation has its limits. The Mcquary Island parakeet and the McCquory Island rail subspecies became extinct in the late 19th century after cats, WA, and other non-native animals were introduced to the island.

[00:16:33]They existed nowhere else but Mccquory Island, and they will never return. The story of Mcquary Island does not end on that small island in the southern ocean.

[00:16:42]The lessons from this campaign are now being studied for use in New Zealand, especially on Steuart Island, also known as Rakura, a large inhabited island that remains under pressure from rats, possums, feral cats, and many other invasive species. If the programs there succeed, they could become one of the most ambitious ecological restoration efforts ever carried out on an island with a permanent human community. From New Zealand to islands across the Pacific, Atlantic, and Indian oceans, more and more countries are viewing invasive species eradication as an opportunity to bring back seabirds, native plants, and ecosystems that were once severely degraded. But McQuary Island also leaves behind a clear warning. Restoration is always difficult and expensive and it cannot bring extinct species back. Do you think people and if you would like to discover more extraordinary stories about how nature can recover, subscribe to the channel and join us for the next