The platypus is an evolutionary anomaly. This duck-billed, semiaquatic mammal is both unique and rare. It’s just one of five egg-laying mammals on the planet. It nurses its young. And it also has reptilian traits: It has a cloaca, maintains a low body temperature (32° Celsius, or 90° Fahrenheit) and males have venomous spurs.

It prefers the lush rivers along Australia’s east coast, using electroreception, sensing electrical stimuli to detect favored food, which includes larvae, shrimp and small crayfish on the riverbed.

The platypus (Ornithorhynchus anatinus) usually feeds during twilight at dusk and dawn, and is elusive,  spending much of its life submerged. Its true population remains unknown. The IUCN Red List estimates 50,000 and classifies the species as near threatened. But that listing was based on an assessment done in 2014, which even then noted it was a “best estimate” and the population was decreasing.

Gilad Bino, who leads the University of New South Wales Platypus Conservation Initiative, said he doubts those numbers. Platypuses are hard to find and count. They face a host of challenges, including destruction of their riparian habitat and encroaching human development.

New research shows that environmental “threat scenarios” are raising the platypus’s risk of extinction. More frequent and extreme weather events endanger platypuses when drought dries the waters they inhabit, wildfires blaze through or floods inundate burrows before the animals can escape.

The research, published in the journal Australian Mammalogy, calls for a proactive response, based on habitat and risk. But effective conservation, the authors note, requires data about where platypuses live and in what numbers.

A little-known, hard-to-find animal

Pre-European numbers are unclear, but there’s evidence that Australia’s Aboriginal peoples stitched platypus pelts together to make blankets. This indicates they were once widespread and abundant along the east coast. One blanket, exhibited in Sydney’s Australian Museum, used 75 skins. Historical records from 1777 to 2006 revealed the presence of platypuses in 268 rivers, yet recent surveys found them in  a little more than half, 56% of those areas.

Efforts are underway to count how many are left. Only researchers with special licenses from state environment agencies are allowed to search for the animals. They wade into rivers or climb into rowboats, working at night along the banks, setting Fyke nets, a type of fish trap, to capture them safely. Often, they wait hours with no success.

“It is a lot of effort to use traditional methods to trap and capture platypus to get their population dynamics, and there are very few people and research groups who are doing so,” said Michelle Ryan. As head of the Hawkesbury Platypus Project, she’s spent six years in the field studying this animal.

Understanding where platypuses live and how many there are, as well as their habits and life cycles, is crucial information needed to focus conservation efforts and emergency responses during natural disasters.

The catastrophic “Black Summer” bushfires of 2019-2020 burned through 240,000 square kilometers (93,000 square miles) across five states: Western Australia, New South Wales, Victoria, Australia Capital Territory and Queensland.

Australia has been heavily impacted by a rapidly changing climate. The Black Summer fires followed a three-year drought that culminated in 2019 — which was one of the hottest and driest years on record in Australia.

“When the fires came through in 2019, in the Blue Mountains, they had no baseline data on platypus, so they didn’t know in those areas that were burnt how the platypus might have been impacted,” Ryan said.

During the drought that preceded the 2019 bushfires, waterways shriveled and dried up, stranding platypuses, said Phoebe Meagher, a co-author on the recent study who works with the Taronga Zoo Conservation Society.

“Taronga [Zoo] received loads of emails and calls asking if there was anything that we could do to save [them] from these drying water holes,” she said.

That placed them at the forefront of efforts to rescue or translocate the animals.

“What became really apparent was that there weren’t facilities for this sort of first response rescue of drought-impacted platypus,” Meagher said. He noted that they have specific requirements for care, including cool, pristine, flowing water — below 25°C (77°F.). They need high-protein live food, such as worms and small crayfish and specialized enclosures with mud embankments for burrowing.

This sparked a realization that temporary housing for platypuses is needed to accommodate animals rescued during a drought, bushfire or flood.

Scientists have now established a framework to save populations in crisis, outlining criteria on whether to help animals in situ or whether they need to be moved. It gives zoos an important role in providing first response to climate-impacted animals.

Citizen science closing the data gap

Citizen science is playing a major role in helping bridge the data gap for the platypus. For example, the Platy-Project invites the public to map sightings. Ryan has partnered with Cattai Hills Environment Network (CHEN) on a project using environmental DNA (eDNA) to log their presence without needing to capture or even see them. Animals leave behind DNA wherever they live, and in this case, researchers can identify and monitor populations by analyzing water samples.

“Taking a water sample and looking for platypus DNA is easy and quick to do. Citizen scientists can do it. Community groups can do it,” Ryan said. Her collaborator, Sue Martin, who is CHEN’s president, has worked with landowners to gain access for platypus surveys along privately owned stretches of the Cattai and Hawkesbury Nepean River catchments.

Overall, there’s little government involvement, which presents challenges for conservation efforts. “There isn’t a platypus strategy for New South Wales,” Martin said, adding that there’s no commissioner or government agency looking after the rivers. “It’s ad hoc and it’s only when catastrophes happen that they put millions into bringing it [river health] back from extinction.”

Pollution as an emerging concern

Pollution from wastewater treatment, mining, industry and urban runoff is a growing threat, with contaminants like PFAS, heavy metals and pesticides reducing platypus food supply.

“If you have an area that has high pollutant contamination, for example, high levels of heavy metals, that will reduce the number of macroinvertebrates available for the platypus to consume,” said Katherine Warwick, a researcher at Western Sydney University. Platypuses consume various insects, larvae, snails, worms and crustaceans.

“Platypuses need to eat about 28% of their body weight in macroinvertebrates per day,” Warwick said. A nursing mother can eat up to 50% of her weight daily.

Without enough food, platypuses may leave their home linear range — how far they swim up- or downriver — which is usually about 15 km (9 mi). But with encroaching development and limited nearby habitat options, this can increase the risk of localized extinctions.

So far, platypus postmortems don’t show heavy metal concentrations at concerning levels, Warwick said.

Although the platypus is a beloved Australian icon, accelerating climate change and intensifying loss of habitat are chipping away at its numbers. Conservation efforts that are restoring habitat and reducing pollution are critical, but Bino warned “when these climate events reach a tipping point, the [platypus] populations will really start to struggle and stress.”

Banner image: This elusive animal hunts in the dim light of dawn and dusk, making it difficult to observe and hard to count. One of the few ways to survey them is by laying nets, pictured here. Image courtesy of Michelle Ryan.

Citations:

Bino, G., Kingsford, R., & Wintle, B. (2020). A stitch in time — Synergistic impacts to platypus metapopulation extinction risk. Biological Conservation, 242. doi:10.1016/j.biocon.2019.108399

Canadell, J., Meyer, C., Cook, G., Dowdy, A., Briggs, P., Knauer, J., … Haverd, V. (2021). Multi-decadal increase of forest burned area in Australia is linked to climate change. Nature Communications, 12. doi:10.1038/s41467-021-27225-4

Hawke, T., Meagher, P., Bino, G., Elphinstone, A., May, S., Lowe, A., … Kingsford, R. T. (2024). Rescue and return: Translocating a semi-wild platypus (Ornithorhynchus anatinus) population during the 2019 drought. Ecological Management & Restoration, 25(3). doi:10.1111/emr.12618

Hawke, T., Bino, G., Kingsford, R. (2019). A silent demise: Historical insights into population changes of the iconic platypus (Ornithorhynchus anatinus). Global Ecology and Conservation, 20. doi:10.1016/j.gecco. 2019.e00720

Hawke, T., Bino, G., Kingsford, R., Lervasi, D., Lervasi, K., & Taylor, M. (2021). Long-term movements and activity patterns of platypus on regulated rivers. Scientific Reports, 11. doi:10.1038/s41598-021-81142-6

Klamt, M., Thompson, R., & Davis, J. (2011). Early response of the platypus to climate warming. Global Change Biology, 17. doi:10.1111/j.1365-2486.2011. 02472.x

Legge, S., Rumpff, L., Garnett, S., & Woinarski, J. (2023). Loss of terrestrial biodiversity in Australia: Magnitude, causation, and response. Science, 38. doi:10.1126/science. adg7870

Serena, M., Williams, G., Bloink, C., & Dekkers, D. (2024). Platypus fyke-netting methods: a review of recommended field protocols and options for assessing population abundance. Australian Mammalogy, 46. doi:10.1071/AM24026

Thomas, J. L., Serena, M., Parrott, M. L., Bino, G., Hawke, T., Brunt, T., … & Williamson, R. (2026). Natural disasters and the platypus (Ornithorhynchus anatinus): criteria and protocols to guide emergency response and interventions. Australian Mammalogy, 48. doi:10.1071/AM25035

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Sharon Guynup Editor

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AnimalsCitizen ScienceClimateClimate ChangeConservationDroughtEnvironmentFiresHabitatMammalsResearchWildlifeZoosAustraliaQueenslandInternational Union for Conservation of Nature (IUCN)

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