It typically starts in the wings and legs of the birds and extends to the rest of the body, causing them to drown or suffocate.

"The birds are conscious but paralysed, and very distressed," she said.

Botulism outbreaks typically occur after the first autumn rains of the year, when warmer waters are combined with low levels of oxygen and high levels of bacteria found in decomposing plants and animals.

Ms O'Sullivan said the outbreaks were natural, but better council management of the wetlands was crucial in reducing the risk of infection.

She said water testing should be carried out regularly in botulism prone areas and oxygenators used to increase dissolved oxygen levels.

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"It is important to get aerators into wetlands known to harbour outbreaks and when outbreaks happen council staff should be out there at least twice daily picking up sick and dead birds," she said.

"Other birds can also become sick by eating the maggots on rotting carcasses of affected birds that have died."

In order to reduce the risk of an outbreak, she advised people to use phosphate-free fertiliser in their lawns, avoid feeding ducks and other wild birds, and keep dogs on a lead to prevent them from feeding on infected carcasses.

She said sick birds could be treated if found early on, and encouraged residents to contact the WA Seabird Rescue if they spotted any birds that seemed to be floating on the same location for long periods of time.

"If birds are found quickly enough they can be treated and have a successful recovery," she said.

"Sadly, it's a time critical thing and often we don't get called about the birds until they are very ill."

Botulism outbreaks are uncommon among humans and other animals, however, they can occur if infected food and animals are consumed.

If you see a bird in distress or that could be affected by botulism, call the WA Seabird Rescue on 6102 8464 or the Wildcare Helpline on 9474 9055.