The Department of Primary Industries and Regional Development (DPIRD) is asking for all starling sightings to be reported, calling on residents of Hopetoun and Esperance to be especially observant.
DPIRD scientists raised the alarm after higher-than-average numbers of the bird were trapped on the State's south coast and near the South Australian border.
The common starling is considered one of the world's most invasive bird pests and poses a threat to WA's agricultural, social, biodiversity and cultural assets, can cause severe damage to high-value fruit crops, especially stone fruits and grapes, and impact livestock feed.
Starlings are small to medium-sized birds with distinctive glossy black feathers and an iridescent green and purple sheen.
Research scientist Susan Campbell said starlings are known to be aggressive and to travel in large roosting flocks causing high levels of noise and droppings.
"We encourage rural landholders and local bird enthusiasts to be vigilant and report any unusual activity, such as birds on the back of livestock or groups of black birds flying in tight groups," Dr Campbell said.
Report unusual bird sightings to the department's Pest and Disease Information Service: 9368 3080, firstname.lastname@example.org or through the department's MyPestGuide Reporter app.
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