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Environment

Weird, Mysterious and Threatened: Can Scientists Save the Platypus?

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A platypus (Ornithorhynchus anatinus) pauses for a moment after being released by scientists into the Little Yarra River, its home stream in Victoria, Australia. (Credit: Douglas Gimesy)

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With the bill of a duck, the body of an otter, and the tail of a beaver, the platypus (Ornithorhynchus anatinus) has a long history of confounding the humans who’ve encountered it. Early European settlers took to calling the strange, semi-aquatic mammals they found living in eastern Australian streams “duckmoles.” When Captain John Hunter, the second governor of the New South Wales colony, sent a specimen of the creature to British naturalist George Shaw in 1798, Shaw initially thought it was a hoax. Thus ensued “a rivalry that pitted nation against nation, naturalist against naturalist, and professional against amateur,” wrote evolutionary biologist Brian K. Hall in a 1999 BioScience article on the history of scientific debate over the species. “Long after the evidence was wrested from Nature half a world away from where the debate raged, biologists continued to argue about this paradoxical creature.”

For much of the two centuries since Western scientists began trying to make sense of this furry egg-laying animal — which shares its reproductive strategy with only one other mammal, the echidna — the scientific literature amounted to little more than descriptions of its odd looks, historical accounts of sightings in this river or that, and cursory observations about its anatomy and life history. That’s largely because, unlike other iconic Australian species like the slow-moving, tree-hugging koala or the ubiquitous kangaroo, platypuses are maddeningly difficult to study. Active at night and living much of their lives underwater, their habits are the opposite of their human observers’. “And beyond that,” says Geoff Williams of the Australian Platypus Conservancy, “everything you typically use in research, you can’t use with the platypus. You can’t look for tracks, and they defecate in the water, so you can’t look for scat.”

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A researcher releases a captured platypus back into Woori Yallock Creek, in Victoria, Australia. (Credit: Douglas Gimesy)

Despite those formidable challenges, over the past 20 years, a few determined scientists — aided by technological advances such as acoustic trackers and environmental DNA (bits of genetic information that an animal sheds into its surroundings) — have begun to illuminate the platypus’s world like never before. The more researchers learn about the species’ life history, whereabouts, and habitat, though, the more they realize just how much of a threat humans pose to its long-term survival.

“The biggest thing we’re learning is that platypuses are in trouble,” says Joshua Griffiths, a biologist for an environmental consulting firm on the outskirts of Melbourne who has spent many sleepless nights capturing platypuses in area streams to learn more about the secretive animals. While some populations are faring well, these tend to be in remote, wild areas. Where the human imprint has altered the platypus’s native waterways, habitat fragmentation, water pollution, fishing nets, dams, and urban development have pushed many populations into decline, Griffiths says. 

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Ecologist Joshua Griffiths holds a platypus while a field assistant prepares to measure the animal’s bill.The platypus was captured as part of a Melbourne Water study to monitor the local population. (Credit: Douglas Gimesy)

Yet many of the same insights into the platypus’s status and the threats it faces have also begun to illuminate a path toward recovery that could spare the species the grim fate that so many of Australia’s other endemic creatures have met. In a country with the world’s highest mammal extinction rate, platypuses could defy the odds — if there’s enough public and political will to protect them.

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(Credit: Courtesy bioGraphic)

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Platypuses — called mallangongtambreet, and boonaburra by Aboriginal groups who once hunted them for food — live in waterways across much of eastern Australia, including the island state of Tasmania. They are well equipped for the life aquatic. Propelling themselves through the water with wide, webbed feet, the carnivores use their much-discussed bills, packed with electrosensors, to locate and catch small prey hidden in the mud and turbid water. After stuffing their squirrel-like cheeks with food, they surface to eat. And they eat a lot: Adult platypuses spend about 12 hours a day foraging, and consume up to 30 percent of their body weight in insects, worms, crayfish, and other invertebrates each day.

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A lone platypus swims at the surface of Lake Elizabeth in Victoria’s Great Otway National Park. (Credit: Douglas Gimesy)

“There are mammals that can live in [fresh]water and can swim well, but nothing comes close to the platypus’s ability to navigate waterways and use its super-sensitive bill to find prey,” says Richard Kingsford, a conservation biologist with the University of New South Wales who has studied the species for years.

What Kingsford, Griffiths, and other researchers have learned has certainly confirmed the platypus’s reputation as one of the world’s strangest animals. For example, scientists suspect  that the venomous spurs that males are born with on their hind legs may be used as weapons against  rivals during the breeding season. After mating, females retreat to the safety of a burrow they’ve excavated into the riverbank. There they lay one or two eggs and incubate them under their wide tails. While it takes only about 10 days for the eggs to hatch, mothers then nurse their young for up to four months until they’re developed enough to venture outside the burrow and forage for themselves.

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The platypus is one of only two mammals in the world that lays eggs — usually one or two per season that the female incubates under her tail. (Credit: Douglas Gimesy)
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Highly specialized feet are among the platypus’s many adaptations to life in eastern Australia’s streams. (Credit: Douglas Gimesy)

Gathering even the most basic information about platypuses has required tremendous dedication. Researchers often spend hours standing in streams  waiting for the nocturnal animals to appear, and all-night watches are not uncommon. To catch them, they  set tunnel-like traps—netting stretched across a series of metal hoops, with long “wings” on either side of the opening to guide the platypus inside. The opposite end is staked up on the bank to ensure enough of the net remains above water for the animal to surface and breathe. Once caught, each animal is measured and weighed and — if it’s a first-time capture — marked before being released back into its home stream.

“They are probably the most difficult species I’ve ever worked on,” says Griffiths, who nevertheless has dedicated the past 12 years of his life to understanding them. One of Australia’s foremost platypus experts, he works with city water officials to study and monitor  populations in waterways in and around Melbourne. “There’s a number of challenges with platypuses, and it’s one of the reasons we don’t have good data on them,” he says.

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Years of dedicated research is beginning to shed light on where platypuses swim and where they face the greatest risks. (Credit: Douglas Gimesy)

As difficult as it has been to study the basic biology of the platypus, it has been even harder to figure out just where all the populations are, and for those that are known, how those populations are faring. But several recent research initiatives are starting to fill those data gaps.

A recently completed three-year national survey by Kingsford, Griffiths and a dozen other researchers combined information from capture-and-release surveys, studies that used acoustic sensors to track platypus movements, environmental DNA data, and historical accounts to sketch out the species’ abundance and distribution, and determine where it’s at risk. The Australian Research Council-funded study, to be published later this month, found that the species is worse off than scientists expected and warns that if the threats that some platypus populations are up against are not dealt with swiftly, the species’ status will only deteriorate further. Using some of the same information, the IUCN downgraded the species’ status to Near Threatened in 2016. Despite this, the platypus has yet to be protected nationally under Australia’s Environment Protection and Biodiversity Conservation Act or at the state level—except in the state of South Australia, where the species is barely hanging on and is listed as endangered. 

All of the evidence so far implicates humans in the platypus’s decline. A panoply of human detritus and structures, including dams, crayfish traps, and pollution have killed the animals, restricted their movements, degraded their habitat and reduced their prey. Some of the most beleaguered populations are those that lie downstream from dams or in areas where land clearing or livestock grazing has eliminated streamside vegetation, including the trees whose roots buttress platypus burrows. Invasive predators, such as feral cats, dogs, and red foxes frequently kill platypuses, particularly juvenile males that must venture out onto terra firma in search of new territories. And fishing nets and traps that allow platypuses to enter but not escape drown many animals each year.

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Crab traps called opera house traps pose a significant threat to foraging platypuses. A wildlife officer shows one such trap that contained the bodies of five drowned animals. (Credit: Douglas Gimesy)

Fortunately, research and conservation efforts in the state of Victoria offer hope for how humans can better co-exist with the platypus. One of the best-studied watersheds is that of the Yarra River, which wends through the heart of Melbourne. While a local newspaper reported platypus sightings in the river in the early-20th century, the animals haven’t been seen downtown since. But there are still several populations upstream and in some Yarra tributaries, and Griffiths has studied many of them, in collaboration with an unusual partner: the local water agency, Melbourne Water. Under the city’s Healthy Waters Strategy, officials conduct surveys for platypuses and minimize threats to them. 

“Because of that, we’ve been able to generate some amazing data,” Griffiths says. A combination of capture surveys, environmental DNA analyses, and a citizen science program that calls on residents to report sightings using a mobile phone app called “Platypus Spot” has provided researchers with a more complete picture of the species’ status in the area. This information is helping water and wildlife managers determine where to focus conservation efforts, and where it’s particularly important to prevent further habitat degradation. The information that Griffiths and others have collected in recent years has also helped convince the state of Victoria to ban a particularly deadly type of trap known as an “opera house trap” (named for their resemblance to the Sydney Opera House).

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Researchers Gilad Bino and Tahneal Hawke work quickly to surgically implant a radio transponder into an anaesthetizedplatypus before its release. Transponders like this are helping scientists better understand platypus movements. (Credit: Douglas Gimesy)

Tiana Preston, who oversees Melbourne Water’s platypus conservation program, says that the agency is using these research findings to help reduce the many threats that platypuses face. For example, the agency  knows now that storm runoff from parking lots and other paved surfaces can flood critical habitat and inundate platypus burrows. To help prevent this, Melbourne Water is working with developers and communities in the city—one of Australia’s fastest-growing — to educate them about the risks to platypuses and encourage them to install permeable pavement that allows rainwater soak into the ground instead, and to put in green roofs to capture rainfall.

This is just one of many fixes that Griffiths and other researchers say are needed across the platypus’s range. Replanting trees along streams, keeping livestock away from riverside habitat that’s still intact, restoring natural streamflows, cleaning up polluted waterways and imposing a nationwide ban on opera house traps are all measures that would help to protect platypuses, they say.

Despite the sobering news that recent research has brought, researchers and conservationists committed to protecting the species all emphasize that there’s still time to revive its ailing populations and make sure the healthy ones continue to thrive. And that would happen much sooner, they add, if policymakers took action now, rather than waiting for additional data. Griffiths, for one, says he’s seen enough to convince him that the platypus already qualifies for protection. “I’d bet my house on it,” he says. 

What is beyond dispute is that the platypus, once so common that it was thought to be an indelible part of the Australian landscape, is now in need of help from its greatest threat: people. “I think we’ve seen beyond any shadow of a doubt that the platypus isn’t a species we can take for granted,” says Williams.

This story originally appeared in bioGraphic, an online magazine featuring beautiful and surprising stories about nature and sustainability.

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