The following information has been received from The Department of Environment and Conservation who are conducting a survey based on bandicoot numbers in Perth.

WA's main environmental agency has launched a survey to track the number of bandicoots living in Perth amid questions over whether the city's growth is reducing their population.

The Department of Environment and Conservation is staging the survey in conjunction with World Wildlife Fund-Australia as part of moves to protect the marsupial.

DEC Swan region ecologist Geoff Barrett said bandicoots, or quendas, had once been prevalent across many parts of Australia but their numbers were thought to be rapidly declining.

Cats were an acute threat to the animals, while urban encroachment was also a significant problem.

WWF species conservation manager Katherine Howard said the survey would compare the results of previous work to see whether there had been changes in the bandicoot population and distribution.

"We're keen to hear from people right across the south-west if they have seen quendas in their local area," she said.

Kanyana Wildlife Rehabilitation Centre hospital manager Margaret Robinson said it was crucial that authorities knew about the state of the bandicoot population.

She said there had been examples in the past where numbers of a native species, such as the woylie, had declined dramatically.

Anyone who sees one of the animals should call 9442 1203.