An outbreak of avian botulism among Perth’s water birds has rescuers scrambling to save lives, and they’re asking the public to help.

Avian botulism is a bacterial disease which survives as spores in water bodies, including sediment and soil. It thrives in low oxygen stagnant bodies of water and causes paralysis when ingested.

Lead vet nurse and clinic manager at Perth Wildlife Hospital, Yasmin Hunter, says Cyclone Narelle’s heavy rains stirred up sediment, causing the dormant bacteria to become active which has led to a rise in cases.

Perth Wildlife Hospital had 35-40 cases of botulism in a flock of ducks coming from Landsdale over the weekend. Fifteen who survived are on track to make a full recovery.

Shift and education event supervisor at Perth Wildlife Hospital Jade Guilfoyle says with veterinary intervention animals with botulism have high survival rates.

“When they are fully paralysed they don’t have the strength to eat for themselves so they get really, really skinny, and eventually unfortunately, pass away,” she says.

Chief operating officer at Wildlife Health Australia Dr Tiggy Grillo says botulism is a common cause of waterbird deaths globally.

“Outbreaks of avian botulism are known to have occurred in Australia since 1934 and occur regularly in many areas of the country,” she says.

Ms Guilfoyle believes climate change is having an effect on the rise in botulism cases.

“Typically we see a decrease in cases during Autumn. Our big outbreaks are usually over summer. Last summer we had an outbreak of over 50 birds who came all from the same location,” she says.

“Botulism can really thrive in really warm, stagnant water. So as our climate gets warmer, as more things are being spread into those waters, it is going to unfortunately get a little bit worse.”

Jade Guilfoyle

Aquatic biologist and director of PASES Aqua Dr. Dulana Herath was hired by Subiaco council in 2024 to remove an outbreak of avian botulism at Lake Julabup in Shenton Park.

He says preventing botulism outbreaks requires a multi-faceted approach. Early detection and rapid response such as removing carcasses and monitoring water conditions are critical to limiting the spread once an outbreak begins.

“Algal blooms contribute to oxygen depletion when they decay, which promotes toxin production. Managing nutrients to prevent blooms is a key preventative measure to prevent avian botulism,” he says.

“Climate change, particularly hotter temperatures and longer dry periods will increase risk of botulism, so strategies and designs need to prioritise water depth, resilience, circulation and nutrient control.”

Ms Guilfoyle says activities like re-vegetation and planting around lakes to promote the aeration of the water will also help prevent future botulism cases.

“So the water is nutrient rich for our ducks but not nutrient rich for our bacteria.”

While this outbreak can be managed, and animals can be saved, Ms Hunter has greater concerns about the propects of Perth waterbirds. She says avian influenza – commonly known as bird flu – has been recorded on islands offshore of Australia and believes it’s only a matter of time before it reaches the mainland, and the consequences are more deadly.

“Avian influenza and botulism symptoms are the same in wildlife but avian influenza protocol requires immediate euthnaisa. So with every suspected botulism outbreak we are on high alert.”

Yasmin Hunter