The childhood pastime of feeding ducks in a park may become a thing of the past, as authorities warn that it could ultimately lead to toxic conditions for wild birds.

Thirty ducks have died of suspected avian botulism at Tomato Lake in Belmont in the past week.

Nicole Davey, environmental coordinator at Belmont Council, said feeding bread to birds contributes to higher nutrient levels in the water, which in turn leads to an increase in the soil bacteria that causes avian botulism.

“So when the birds eat snails and worms that are in the mud, they become infected with the bacteria, when releases a toxin that causes them to become paralysed, and eventually they die," she said.

“The bacterium level is normally low or is dormant, but we believe that when conditions are right it increases.

“The ducks are the first to be affected, but it will affect other birds like spoonbills eventually.”

The council is waiting on final testing to confirm in the cause of death but is urging the public not to feed any birds in public waterways.

Nicole Davey said there is little chance of humans becoming ill.

“There is minimal risk to humans unless they eat birds from the lake but it is best to avoid the water,” she said.

Outbreaks common

Dr James Haberfield is a bird and reptile specialist at Murdoch University Veterinary Hospital. He sees many birds suffering avian botulism infections at the end of summer when water levels in urban wetlands are low.

The bacteria becomes more concentrated and “an outbreak that wouldn’t be an issue in the middle of winter becomes really aggressive,” Dr Haberfield said.

“Birds come in very limp and have no control over their limbs.

“The reason they often die is because the bacteria targets the end of the nerves and their respiratory muscles become paralysed.

“They just get to the stage where they are totally paralysed and unable to feed; they also drown in the wild.”

Dr Haberfield said there no direct link between feeding bread to birds and botulism, but it can add to conditions which make birds ill.

“If you are feeding all these birds and encouraging them to come into the area, then the volume is higher,” he said.

“Food like bread is higher in nutrients than food in the wild

“People feed bread to ducks all the time and don’t see any problems, but in reality we really shouldn’t be feeding any wild animals.”