Birds die as botulism thrives

Ducks killed from botulism in Titirangi in 2004. File Photo / Supplied

Animal protection authorities are pulling "bagfuls of dead birds" from Auckland's waterways as the warm, sticky summer compounds the spread of a toxin outbreak.

Hundreds of dead or sick birds suffering from paralysing disease botulism have been found by officials or handed in to animal shelters.

In one case, the SPCA has spent days pulling several species of dead and dying fowl from a disused quarry in South Auckland.

Auckland SPCA inspector Vicki Border said the current outbreak of avian botulism was the worst she had observed in Auckland.

New Zealand Bird Rescue Trust spokeswoman Lyn MacDonald said this summer's warm temperatures had heated up some waterways to 26C, making them breeding grounds for bacteria which produced the toxin.

Botulism is a form of food poisoning, caused in water birds by hot weather releasing toxins from dead weeds or other pollutants in shallow, still water. All water-based birds in Auckland can be affected by the bug.

The toxin causes birds to lose control of their head and necks before the paralysis spreads to the rest of their bodies.

Botulism is commonly found in Western Springs and Auckland Domain, where the feeding of ducks with bread can add to pollution, and therefore the creation of deadly microbes.

In South Auckland, Ms Border estimated that hundreds of birds had died, including ducks, swans and even pukeko which fed from the edge of the water.

"The waterways are massive, and while we're getting great help it's difficult. There are no boat ramps or easy access, and we're really struggling to mitigate the suffering the animals are in."

Avian botulism is a very low risk to humans, but health authorities warn that people should clean their hands if they have touched sick or dead birds.

AVIAN BOTULISM

* A paralysing, often fatal disease which is caused by a botulism bacterium.

* Birds suffering from the bug will have sluggish movements, and will struggle to use their wings, raise their heads or feed.

* The toxin thrives in still, shallow, warm water and is common in urban waterways or ponds.

* Most birds will recover if fed fresh water, put in shade and injected with antitoxin.

* Avian botulism cannot be transferred to humans.

* The human strain of botulism is very rare, though the muscle-relaxing treatment Botox is related to the toxin.