The discovery is partly thanks to DNA testing, and partly thanks to the work of dedicated citizens, who have reported sightings of the platypus over the past few years.

DNA testing revealed platypus in two out of nine sites on the upper Campaspe River. Testing showed platypus in six out of eight sites along the Coliban River.

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The conservancy said that sightings were a better way to detect platypus in the area.

People reliably reported platypus at four out of the nine Campaspe sites, and seven out of the eight Coliban sites within the past three years.

Conservancy biologist Dr Melody Serena said the platypus distinctive appearance meant sightings were an effective way to map where they were.

Dr Serena said a DNA survey could only identify platypus over one small window of time, but platypus could be seen throughout the year.

She said reliable environmental flows from reservoirs along the Coliban probably explained in part the wide spread of platypus.

To report a platypus sighting, visit: platypus.asn.au/

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