Drought and Fire Are Pushing Australia’s Platypus to the Brink

Ecologists are racing to gather data on the curious monotremes as climate threat looms large.

ONCE MY EYES ADJUSTED to the glow of the moon and a sky speckled with countless clusters of stars, the paddock and winding waterway beneath seemed surprisingly brightly lit. Dingo Creek no doubt once teemed with platypuses dabbling in its depths, probing their duck-like bills into the mud for water beetles, dragonfly nymphs and yabbies.

Along with four species of echidna, the platypus is one of only five living monotremes – unusual, egg-laying mammals that retain a number of reptilian features. Photo by George Chapman.

That night, we were hoping to find some, but here on the New South Wales (NSW) Mid North Coast and in streams across southeastern Australia, increasing evidence suggests these peculiar mammals have long been declining — and that they took a serious hit in the recent drought and the subsequent bushfire crisis it helped spawn.

Following the driest period on record in many parts of southern Australia, the platypus has undoubtedly gone locally extinct in some creeks across its range, said Gilad Bino, an ecologist at the University of New South Wales (UNSW) in Sydney.

“Normally, if a population goes extinct because of droughts and bushfires, then that area might get recolonized,” he added. “But other threatening processes, such as land clearing and dams, are preventing movement of individuals between rivers and fragmenting populations. So, over time, you get populations disappearing without possibility of recovery.”

Here in Bobin — an hour and a half inland from Port Macquarie, and part of the watershed or catchment of the Manning River — the Rumba Dump bushfire swept through on 8 November 2019. It razed the local school, homes, and even dry paddocks. It burned riparian vegetation surrounding the creeks and then subsequent rains washed all the ash and sediment into them, threatening the fishes, platypuses, and other creatures they contained.

Nine months later, at the end of July, I was there with Bino and research ecologist Tahneal Hawke, who are both studying the platypus (Ornithorhynchus anatinus) at UNSW’s Centre for Ecosystem Science. With post-bushfire funding from the World Wildlife Foundation, the pair was surveying health and numbers of platypus in both burned and unburned creeks in the Manning and Hastings River catchments.

These monotremes are shy and difficult to catch. They are largely nocturnal and forage for invertebrate prey at night, so earlier that day, we’d laid several types of nets in five locations to see if any had survived here. Around the creeks, things looked green and lush with herby regrowth, but the blackened trunks of trees and fragments of soot and ash around the banks revealed that little here had escaped the flames.

In four sites along the shallow, pebbly bottom of Bobin Creek we’d laid ‘fyke’ nets, which funnel foraging platypuses into a soft tube of netting they can’t reverse out of. These were checked every three hours. Five minutes’ drive away, in deeper Dingo Creek, we’d paddled out in a tinnie and dropped a mesh net along the center, which hung from floats; this was aimed at catching platypuses as they swam back and forth from bank to bank, foraging along the river bottom.

Once night had fallen, Bino and Hawke took turns keeping an eye on the mesh net from the bank. They checked every few minutes with a spotlight for movement in the water and listened out for the tell-tale splash that might indicate a platypus had become entangled.

“We have to sit by it constantly, because there is the chance that fish might weigh it down, or it could get snagged on some vegetation, which means the platypus might not be able to surface for air,” Hawke explained.

There was nothing else to do but wait. However, given that both creeks dried up here in 2019 — a phenomenon that locals had never witnessed before — it wasn’t even clear if platypuses remained, or if our efforts that afternoon and the nocturnal vigil might be in vain …

COMING UP TO 10 pm on that mild winter night I had almost given up hope that any platypuses were left in this stretch of Dingo Creek, when Bino heard a splash and noticed ripples around the net hanging from floats along the center of the river.

He hopped from the bank into the tinny and paddled out to the net, which he tugged onto the boat before disentangling the platypus.

At this point, utmost caution must be used, as (among the species’ many oddities) males have venom spurs near the heel of each hind limb. While not lethal to humans, it is “excruciatingly painful,” said Hawke. “You’d probably pass out from the pain. There’s no antivenom, and morphine doesn’t have much of an effect, so you can go to hospital, but there’s not much they can do.”

Bino lifted the platypus by the top of its wide, beaver-like tail. “You use a lot of care when handling,” said Hawke. “They can’t wiggle enough to spur you in that position, but any other position they will take advantage of it.”

In any case, a first glance suggested this one was a female because of its small size. Breeding season was about to begin and younglings or puggles don’t emerge from their riverbank burrows until January to March, meaning this was not likely a juvenile male.

After cutting her from the net, Bino softly plopped her into a pillowcase and left her to calm down. “They seem to relax very quickly once you wrap them up. I don’t know if it feels like a burrow. Sometimes, even putting a hand on them seems to relax them,” he said.

In the paddock above, under the cool light of the moon, Bino got to work. He put the platypus on a folding table and anaesthetized her with isoflurane gas from a nozzle specially created to fit snuggly over a platypus’s bill.

“Drawing blood is from the bill, so you can imagine trying to draw from an awake animal — it would be very stressful and painful,” said Bino, an Israeli-Australian who lives near Byron Bay with his family.

“It’s a sensitive organ for the platypus with their electroreceptors.” Hawke added that: “anaesthetizing is for their benefit, but I am much more comfortable handling them. I used to have nightmares about it, all these dreams about getting spurred.’

The platypus was a little bigger than I had anticipated — plump and about 40 centimeters head to tail. Her eyes were tiny (they close their ears and eyes underwater and rely on their electrosensitive bills to detect the movement of prey). She had coarse hair on her back and around her tail, which transitioned to exceedingly soft, pale fur on her belly. Her bill was leathery and much softer than I had imaged.

Bino took a flabbergasting number of measurements and samples. Weight, body length, bill length, spur size, and tail volume index were all noted down; platypus store fat in their tails and squeezing them to see how much they bend is an indicator of overall health. Samples of blood, urine, parasitic ticks, fur, claw clippings, and a skin biopsy followed. Finally, a swab of ground-up invertebrate prey was taken from inside the creatures’ hamster-like cheek pouches, to see what she had eaten, and then a tiny microchip was inserted via a needle, which will tell them in any future surveys that this individual has been caught before.

“Because there is such an effort in catching platypuses, we try to maximize the data we can take from any individual,” Bino said. Thankfully, this one seemed healthy and well fed — but the fact they’d only caught two in one week suggested that following the devastating drought and the bushfires, very few might be left in this river system. She was returned to the comfort of the pillowcase while the anaesthetic wore off, before being set back down on the bank of the river. Then she scurried off with a splash into the water; the creek and the night engulfing her.

Along with four species of echidna, the platypus is one of only five living monotremes – unusual, egg-laying mammals that retain a number of reptilian features.

Known as boondaburra, mallingong, tambreet and dharragarra by some of the many Aboriginal language groups across its range, one Dreamtime story suggests the platypus was hewn from a romantic union between a duck and a rakali, or native water rat. The first European naturalists to set eyes on specimens sent from Australia were equally baffled by the species’ perplexing mashup of features, believing the creature to be a hoax.

Dubbed “the world’s strangest mammal” by The New York Times, the platypus once flourished in waterways from the tropics of Queensland to the snow-smothered peaks of Tasmania. But the work of the UNSW team suggests it has not been seen for a decade or more in 41 percent of sub-river catchments where it was recorded historically.

Bushfires are problematic for platypuses, as the loss of shade around small streams and pools they inhabit can make water intolerably warm — which is anything above about 28 degrees Celsius.

“Platypus are weird little creatures in that they don’t have any way of getting rid of heat. Their only response to warm water is to just sit in their burrow and hope it goes away. They also need to feed really actively, taking in about one-third of their body mass each day,” says Thompson. During the terrible ‘Millennium’ drought 20 years ago, many platypuses simply retreated into their burrows and died there, he adds.

“They are more susceptible to heat than cold,” agrees Hawke. “They tolerate the cold really well; we’ve caught them in the snow, and they live under the ice in the highlands. But, they are constrained in their distribution by warm waters up in northern Australia.”

Sediment after fires makes streams shallower, and less buffered from the heat on hot days, as well as often rendering them unsuitable to platypus, which prefer to forage in water 1 to 5 meters deep. Lintermans says that when a 1.8-meter river pool he was monitoring following a fire in the Australian Capital Territory (ACT) filled with sediment, its depth was reduced to 80 centimeters.

The effects of sand, gravel, and boulders washing into streams can be very long lived too, he adds. For example, sand generated by overgrazing from rabbits in the 1800s is still working its way through the upper Murrumbidgee River catchment.

If floods or the loss of vegetation cause banks to collapse then platypuses have nowhere to dig their burrows, which they must retreat to, to sleep, during the heat of the day.

For all these reasons and more, it’s possible the platypus could become locally extinct in northern Queensland and west of the Great Dividing Range, says Thompson, which are the northern and western extremities of its range. His research suggested this was already on the cards with climate change.

“Vegetated streams are really important refuges for a number of iconic native species, like the platypus. If fire goes through these refuges and they are left unvegetated and water temperatures get a lot higher, then we may actually lose some of these species. Platypus are right at the limit of their temperature range anyway in some places, so we might see localized extinctions,” he says.

“It’s becoming a death by 1000 cuts. The Millennium drought knocked back a lot of our freshwater biota. They’ve never quite recovered in many cases, and now we have these big landscape-scale fires … It’s a real concern.”

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