Platypuses have been detected swimming through Melbourne creeks and rivers, including close to the CBD.
Traces of platypuses were found across dozens of waterways in Greater Melbourne, from Macedon Ranges down to Mornington Peninsula and Bass Coast.
A program run by Melbourne Water between 2021 and 2023 analysed DNA including feces, skin and saliva shed across the organisation's catchments to map where the animal has been.
"Platypus are quite shy, occur in a variety of habitats and are predominantly nocturnal," said Dr Rhys Coleman, manager of the waterways and wetlands research at Melbourne Water.
"It can be difficult to monitor their activity through traditional methods alone."
Studies by Melbourne Water have revealed the largest platypus populations across Melbourne occur in the Yarra River and Bunyip River catchments, with small populations in areas such as the Dandenong Creek.
Scientists were surprised during the program there were traces at Mornington Peninsula, where there have been public sightings but no other evidence until now.
Platypuses were also detected close to Melbourne CBD, which the water company believes was as a result of feeding or as a route to a different waterway.
It's not all good news though for the elusive semiaquatic mammals.
Dr Coleman says their population is declining.
"Climate change and increasing urbanisation are impacting platypus habitats," he said.
Increased water runoff from hard surfaces such as roofs or roads into stormwater drains, which flows into waterways, can lead to contaminants in the water, including litter which can tangle around animals and cause death.
Climate change is also resulting in less water in rivers, as well as dryer climates and increased temperatures affecting water temperature, which negatively impacts platypus food sources.
