Bread Makes Toast of Ducks, Vet Says

Aiona Fernandez and her wide-eyed, stroller-bound son, Benjamin, were greeted by squawks from mud hens, white geese and green-necked mallards that dived greedily after bits of stale bread the pair tossed into the lake at Laguna Niguel Regional Park on Wednesday morning.

Little did they know, those scraps may be deadly. Bread fed by humans is thought to have caused the botulism deaths of more than 20 male mallards at the lake since late October.

Autopsies of the dead ducks by the chief of Orange County’s Veterinary Health Agency revealed the cause to be avian botulism, Laguna Niguel lake manager Rick Mendoza said Wednesday. Dr. Carol Cardona, a veterinarian at UC Davis, believes bread is the culprit.

“The bread is an unusual problem,” Mendoza said. “People are feeding it to thousands of ducks, and it’s the worst thing in the world for them.”

Clostridium botulinum bacteria--which feed on animal carcasses and other rotting material, including stale bread--produce the botulism toxins. The poisons, when ingested, can cause fatal damage to an animal’s central nervous system.

But the fact that the disease has affected only male mallards has confounded both Mendoza and Dr. Richard Evans, chief of the Orange County Veterinary Health Agency.

Cardona speculated that the male mallards’ aggressiveness may be their downfall. The stronger ducks are able to muscle their way to more bread, increasing their chances of being poisoned.

Evans said there is no threat to humans who eat trout or other fish caught in the lake. Different animals have varying degrees of sensitivity to the toxin, and in the case of the lake in Laguna Niguel, it is just high enough to be lethal for ducks, he said.

Most of the fishermen lakeside Wednesday said they wouldn’t think twice before eating fish from the lake.

Ryan Momia, who had a string of five trout floating in the water, said he’s glad to have less competition for the fish.

“Those birds are a pain,” said the 19-year-old from San Pedro. “I’m not going to miss them.”

But Fernandez and her 13-month-old son were horrified to learn that they may be harming the ducks.

“I had no idea. I just thought I’d bring the bread here instead of throwing it in the bin,” the Laguna Niguel woman said. “I’ll never do it again.”