They are really unusual mammals as they lay eggs!
In the Perth region the only monotreme repesentative is the Short-beaked Echnida (Tachyglossus aculeatus). They are probably more common in the bush than seen.
The best place to see them is Dryanda Woodland – about 2 hours out of Perth – a strong holdhold for many other marsupials. I have also seen them by chance in the Perth Hills and near the Julimar State Forest.
Echidna are found throughout most of Australia. In PNG there are 3 other long-beaked species in the genus Zaglossus.
The only other monotreme species is the Platypus Ornithorhynchus anatinus found on the east coast of Australia – not on the west coast.