100 Birds Die as Botulism Strikes Early at Salton Sea

A late spring heat wave triggered an outbreak of bird botulism at the Salton Sea, killing more than 100 pelicans weeks before the disease normally strikes each summer, federal wildlife officials said Wednesday.

The early outbreak of avian botulism, which occurs when birds eat infected fish and generally hits as summertime heat peaks, could leave surviving pelicans susceptible when temperatures rise again, said Charles Pelizza, senior wildlife biologist at the Sonny Bono Salton Sea National Wildlife Refuge.

Pelizza said the June outbreak abated in recent weeks and biologists were hoping a fast response by wildlife officials will keep the final toll below that of last year, when nearly 800 birds died during an unusually long, 4-month outbreak.

“We weren’t expecting it a month early,” Pelizza said. “It could potentially get bad--much worse than it’s been. It’s certainly not over.”

State and federal wildlife officials are patrolling the vast lake in airboats, capturing four to six sick birds on each trip.

About 120 California brown pelicans and American white pelicans have been treated at a bird hospital at the refuge and at five volunteer-run facilities around Southern California.

Two more brown pelicans, officially listed as an endangered species, were captured Wednesday. Toxins are flushed by feeding the pelicans electrolyte-laden fluids through a tube placed down their throats.

The disease is caused by bacteria that flourish in warmer temperatures and infect the Salton Sea’s population of tilapia fish. The diving water birds, once infected, become listless and lose their ability to fly. Many pelicans die by drowning, Pelizza said.

Recovering dead birds is an important part of containing an outbreak, he said. Humans are not generally at risk, biologists said.

The Salton Sea’s most serious instance of avian botulism came in 1996. It killed 13,400 pelicans--nearly a third of the area’s pelicans--along with 3,000 other birds. Since then, officials have sought to identify outbreaks and start treating sick birds immediately.

“We’ve gotten more proactive and gotten ahead of the curve by getting the birds out of the water,” Pelizza said.

The outbreaks are but one of the ecological problems facing the lake, which straddles Imperial and Riverside counties 85 miles east of San Diego and is a key stopover for migratory waterfowl.

Fed by agricultural runoff and sewage, it has been the focus of planning efforts by federal and local officials to reduce pollution and salinity. Despite massive die-offs of fish and birds, it remains a productive fishery.