Scores of wild mallards have been found dead or dying this week along widely separated stretches of the Los Angeles River in Glendale and Long Beach, apparently victims of an outbreak of botulism aggravated by the drought, wildlife officials said Friday.
Los Angeles animal regulation officers picked up about 30 dead ducks Friday on the concrete banks of the river along the Golden State Freeway near Griffith Park. State fish and game officials found another 30 to 40 in percolation ponds near the Long Beach and San Diego freeways.
Several ducks, too weak to walk, also were captured for treatment and examination.
Water in the river was tested for toxic chemicals, but officials said they suspect that the birds were hit by a mild outbreak of botulism, a type of bacterial poisoning that thrives in warm, wet environments. The bacteria can be transferred easily between ducks, but does not usually affect humans or other animals.
“It’s pretty much a duck thing,” said Earl Luppe, a wildlife management supervisor for the Department of Fish and Game.
The deaths, which began about a week ago, worried residents along the river, who feared that the water may have been contaminated.
But Irwin Biederman, a hazardous-materials specialist for the county Department of Health Services, said he doubted that chemical contamination killed the birds because other animals along the river were unaffected. And officials investigating the Glendale deaths ruled out a virus because it would most likely have affected a wider area.
Luppe said botulism outbreaks are relatively common among ducks in warm weather, and generally are restricted to isolated areas because the bacteria concentrates in small pools of standing water. But wildlife experts said it is important to remove dead ducks quickly so they do not infect other birds migrating south this fall.
Michael Burns, supervisor for the northeastern area for the city Department of Animal Regulation, said the drought may have played a role by shrinking water holes, forcing large numbers of ducks to share smaller pools of water.
Ten ailing ducks were taken to the Glendale Humane Society’s shelter Wednesday and Thursday by society workers. Two of the birds died, but the rest were released Friday to the Pacifc Wildlife Project in Laguna Niguel after they appeared to be recovering.
“They seemed to be coming along quite well,” state humane officer Joseph Sykora said.