How Australia’s Eastern Barred Bandicoot Came Back From Extinction

Eastern Barred Bandicoot
An eastern barred bandicoot explores its space in the Werribee Open Range Zoo. Courtesy of Zoos Victoria

The first time the large Maremma sheepdog sees the tiny eastern barred bandicoot across the enclosure, it cocks its head to one side and stares. The bandicoot, a small, endangered marsupial native to southeastern Australia, freezes in place. For bandicoots, becoming immobile in this way is an evolved response, one that always worked well against Australia’s formidable array of aerial predators. It worked less well, however, when land predators, especially foxes, were introduced to the continent, eliminating the eastern barred bandicoot from the wild by the 21st century. But the Maremma is here to protect the marsupial, not hunt it. The bandicoot begins to relax and eventually moves around the enclosure. When the dog resists the urge to chase the bandicoot, it receives a treat from its owner.

At first, scenes such as this one took place only in enclosures, part of a process of training and habituation for the dogs. As the dogs learned not to chase their charge, conservationists placed this gregarious canine known for guarding sheep near the bandicoot in two unfenced farmland areas in the bandicoot’s historical range, west of Melbourne. Conservationists hope that the dogs will stay near the solitary marsupial and ward off fox attacks. If this experiment—believed to be the first time in the world that sheepdogs have been used to re-establish a wild population of endangered mammals—works, the eastern barred bandicoot may survive free of fences on the Australian mainland for the first time in decades.

The effort is the latest step to allow the tiny marsupial to rebound. In September of this year, thanks to three decades of captive breeding and releases at seven protected sites—on islands and in enclosures—the Victorian state government upgraded the eastern barred bandicoot from extinct in the wild to endangered. It was the first time that an Australian mammal species had been upgraded in this way. Scientists and bureaucrats were so certain that the species’ future was secure, thanks to protected habitats and innovative conservation efforts, that they discontinued the captive breeding program.

“To the best of my knowledge, it’s a world first to shut down a long-term captive breeding and insurance program because we’re no longer needed,” says Marisa Parrott, a reproductive biologist and head of Zoos Victoria’s captive breeding program. “There have been animals that have been extinct in the wild and have been reintroduced—the Arabian oryx and Mongolian wild horse, or Przewalski’s horse, for example. But they still have global breeding programs there to support them. This one is completely different.”

How Australia’s Eastern Barred Bandicoot Came Back From Extinction
A guardian dog rests at a bandicoot release site. Courtesy of Zoos Victoria

The eastern barred bandicoot is a digging mammal that measures about a foot from tip to tail and weighs, on average, about a pound and a half. One of six bandicoot species in Australia, it has muted white stripes on its hindquarters and an elongated conical snout that is custom-made for digging out the insects and other invertebrates on which it feeds; one bandicoot can turn over more than 28 pounds of soil in a single night. When startled, it can leap six feet into the air, or run in a zig-zag fashion.

Eastern barred bandicoots once roamed the plains of western Victoria and into South Australia. No-one knows how many inhabited the area, but their former range extended across 7800 square miles and the population may have numbered tens, possibly even hundreds, of thousands. But this habitat was turned into the richest farmland in southeast Australia during the 19th and early 20th centuries, and the cute marsupials suffered in a country with the world’s worst record of mammal extinctions. Today, less than one per cent of Victoria’s native grasslands persist. To add to the declining sub-species’ woes, colonists introduced foxes into the area in the 19th century. “One fox in an area of bandicoots is one too many,” says Amy Coetsee, a threatened species biologist and one of Australia’s leading experts on the marsupials. “They simply can’t cope with any level of fox predation.”

By the 1980s, just one population of between 150 and 200 bandicoots survived, around the farming community of Hamilton. It was, one report noted, “rapidly trending towards extinction.” The last wild eastern barred bandicoots sought refuge in wrecked vehicles in the Hamilton town dump.

In 1988, the Victoria state government formed a recovery team that brought together government agencies, Zoos Victoria, volunteer groups and other stakeholders. That year, scientists removed 40 bandicoots from this population to form a captive breeding program. Soon after, eastern barred bandicoots disappeared from the wild in Victoria. The only remaining breeding population existed in small pens at Woodlands Historic Park. In the years that followed, the breeding program extended to other zoos and wildlife sanctuaries across the country. “We know that every single mainland eastern barred bandicoot today can be traced back to that program,” says Parrott. “Without the captive program, the sub-species would be extinct.”

Eastern barred bandicoots were well-suited to captive breeding. They have the second-shortest pregnancy–just 12-and-a-half days–of any known mammal. At birth, Parrott says, “they look like jelly beans and they’re about the size of a tic-tac or smaller.” Within a month they are no longer permanently attached to the teat. At two months they are weaned, and the mother is already breeding again. Eastern barred bandicoot mothers can give birth one week after weaning the previous litter, and can have up to five litters in a year.

“Add to that that the females can become sexually mature and pregnant at only three months old, the males generally at around five months,” says Parrott, “and you just have this amazing species that has such a quick and remarkable reproductive strategy.”

Breeding was one thing. Re-establishing wild populations was altogether more difficult. Six times captive-born bandicoots were released into the wild. All six reintroductions failed when foxes killed the bandicoots.

A 2011 recovery plan zeroed in on the root causes of the bandicoot’s decline: no more releases would be done until foxes were gone from an area. The plan set an ambitious goal of releasing 2500 eastern barred bandicoots across nearly 10 square miles—including four fenced sites and some of Victoria’s fox-free islands. By 2013, three fenced sites covering roughly three square miles had been built.

What changed everything was the release of introduced bandicoots onto tiny Churchill Island in 2015, Phillip Island in 2017 and French Island in 2019. Fox-free French and Phillip islands offered just over 70 square miles of bandicoot habitat, and the bandicoots have already begun breeding and expanding their range across these islands. Although results of island surveys are still pending, Coetsee, who ran the reintroduction program on French Island says that “they’re definitely established on French Island, and I don’t need to worry about them anymore.” At the end of 2020, bandicoots were released into Tiverton, a nearly four-square-mile fenced property of native grasslands northwest of Melbourne.

By September 2021, 1500 eastern barred bandicoots had spread across four fenced areas and three islands. Thirty-three years after eastern barred bandicoots were first taken into captivity, the Victoria state government made that change in their status from extinct in the wild to endangered. “The first step was stopping them going extinct,” says Parrott. “The second step was recovering them to this point. The future step is making sure we have the healthiest population possible.”

How Australia’s Eastern Barred Bandicoot Came Back From Extinction
An eastern barred bandicoot is released in an unfenced site guarded by Maremma sheepdogs. Courtesy of Zoos Victoria

The lack of genetic variation in the Victorian sub-species—two sub-species exist of the eastern barred bandicoot, the mainland or Victorian one, and another on the island of Tasmania—worried the recovery team. A 2013 study by Andrew Weeks, an ecological geneticist from the University of Melbourne, found that every living eastern barred bandicoot descends in some way from just 19 of the original 40 bandicoots taken into captivity. He discovered that Victoria’s eastern barred bandicoots had lost 40 percent of their genetic variation in two decades.

 “We know that genetic variation matters through time,” says Weeks. “It may not matter right now, in that they can survive right now for whatever reason. But as soon as a disease comes along, as soon as climate change really impacts the way that they operate in the environment, they’ve got nothing to draw upon, and that’s when it really matters.”

In 2013, eastern barred bandicoots in a fenced site west of Melbourne began turning up with under-developed lower jaws. “For a bandicoot that’s pretty important,” says Nigel Sharp, director of Mt Rothwell, where the defect was first detected. “They push their nose into the soil. That’s their part of the engineering process. And they can’t really do that if their jaw is not supporting it.”

The abnormality had come through the captive breeding program, but had gone undetected until after the affected bandicoots were released into the wild. It was a direct result of the sub-species’ lack of genetic diversity, dating back to the 1988 bottleneck. “The clock was ticking,” says Richard Hill, head of the recovery team. “We were losing genetic diversity at each step along the way.”

The recovery team launched what’s known as a genetic rescue. This meant taking Tasmanian bandicoots from the island south of Australia and breeding them with the endangered mainland animals. The two sub-species had been separated for up to 15,000 years, after rising sea levels drowned a land bridge that connected Tasmania to the mainland, but their genetics remained almost identical. The breeding was successful and the offspring from the two sub-species will now provide the basis for all new wild releases. “There’s still a lot of diversity in Tasmania,” says Weeks. “By introducing it, we’re effectively able to double the diversity found within the Victorian population.”

After scientists had established populations on islands and fenced in enclosures on the mainland, researchers looked to expand their efforts to open grasslands. In 2015, David Williams began training his Maremma dogs to look after eastern barred bandicoots. At first, this meant putting the dogs and bandicoots in separate enclosures so they could see each other, then introducing them into the same enclosures. It would take five years before Williams decided that the dogs were ready. Maremmas had already helped save little penguins on Middle Island, off south-western Victoria. Foxes had almost driven a breeding colony of little penguins to extinction on the island when, in 2006, Maremma dogs were introduced to deter foxes and protect the penguins from predation. The penguin population recovered, and the dogs remain on Middle Island to protect the colony.

Unlike the penguins, bandicoots are solitary, so Williams and his team adapted the idea: the Maremmas would look after sheep in large open grasslands where bandicoots lived. As long as there were sheep in the bandicoots’ territory, the Maremmas remained, and as long as the dogs were around, the foxes were far less likely to linger. “It’s not a complete exclusion of the foxes,” says Williams. “The idea is that when the foxes are in the dogs’ territory, they know they’re in the dogs’ territory. They might pass through it, but it limits the amount of time that they’re comfortable to spend in there.” 

Over the past two years, the recovery team has released 40 bandicoots into two grazing properties in western Victoria, with two to three Maremmas and hundreds of sheep at each site to keep them company. Scientists can’t yet say whether the experiment is working. But some of the bandicoots have bred, and initial camera-trap evidence suggests that foxes, if they pass through the area at all, rarely stay for long.

Some setbacks have occurred. “There are some individuals we can’t account for,” says Williams. “But animals die all the time in the wild. Bandicoots aren’t long-lived critters anyway. Ideally, we’re slowly breeding the most predator-wary ones, and if they continue to reproduce, we can establish a self-sustaining population.”

“We know that fences work,” says Parrott. “We’ve done the research that shows that islands work. This is that next step to say, what else can we do to get them safely back out where they belong? If it works for bandicoots, it could actually work for a lot of other animals, too.”

In the meantime, the release of eastern barred bandicoots into the wild continues. For Parrott, it’s always a special moment. “They’re back out where they should be and where the habitat should have them. You take these little animals out there, open the box and wish them well as they head off into the night.”

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