Peel residents are being urged by local wildlife rescue groups to be on the look out for magpies suffering from paralysis.
There has been a recent increase in the disease, first reported in WA in 2018, especially in the Perth area.
However, there are fears it is spreading to Mandurah, with one case already presenting to Mandurah Wildlife Rescue group last week.
"Sadly the people had held the bird overnight before bringing it in," a spokesperson for the Mandurah Wildlife Rescue said.
"There isn't much we can do for them after the first 24 hours. We play a supportive care role and there's really not much we can do unless we get them in for treatment early.
"It's so vital to take them [birds showing symptoms] straight to a vet or a licensed rehabilitation centre so they have the best chance of survival," she said.
Recent research suggests the disease is a form of botulism, especially as cases seem to peak in summer and autumn. Botulism is normally associated with waterbirds, according to a spokesperson from Parks and Wildlife Service, but could occur in carnivorous birds like magpies if they ingest the toxin by eating maggots which have been feeding on infected carcasses.
Sometimes known as the Black and White virus, it strikes other carnivorous birds such as butcher birds, ravens and mudlarks too.
According to the Mandurah Wildlife Rescue spokesperson, signs to look out for are birds who are unable to lift their heads or fly, but don't have any outward signs of injury such as broken wings. They can also have curled up talons and be weak and shaky.
"I can't stress enough how important it is to get these birds help as quickly as possible," she said. "We're still learning more about the disease, so it's really important to get information from the public about where they're finding the birds so we can build a database; and also for returning them to the right place if they recover."
