Residents within a 30-kilometre radius of Perth Zoo are being asked to look out for squirrels following a sighting in Victoria Park.
Department of Agriculture and Food invasive species manager Richard Watkins said WA had no native squirrels and the northern palm squirrel spotted was a feral pest.
Northern palm squirrels were familiar characters at Perth Zoo where they were deliberately released in 1898.
The squirrel population remained contained within zoo grounds for many years but over time the squirrels spread to surrounding suburbs.
They are about the size of a rat with a bushy tail, have rapid, darting movements and are good climbers.
Mr Watkins said the animals damaged plants by eating fruits and buds and could damage electrical wiring in houses. A control program to reduce the squirrel population started in 2012.
“Now only a very small number of squirrels remain in the South Perth area and an increase in squirrel numbers could threaten market gardens, backyard vines and fruit crops, damaging a wide range of fruit, nut and vegetable crops,” he said.
A Perth Zoo spokeswoman said the squirrels used to be a fixture within the grounds many years ago.
“But as they are a pest species we implemented a control program some years ago and therefore do not have them anymore,” she said.
Reports can be made using the MyPestGuide app or calling the department’s pest and disease information service on 1800 084 881.