DFG veterinarian Pam Swift had reported earlier in the week that they believed avian cholera was to blame but were awaiting final tests.

On Thursday morning Andy Atkinson, a senior wildlife biologist supervisor, confirmed a final diagnosis of avian cholera.

Atkinson said that tests had also been conducted to detect signs of avian influenza and Newcastle's disease, but that neither of those diseases were found.

Lynette Shimek, DFG's Lake County game warden, said 700 dead birds were collected Thursday, bringing the total number of animals picked up by DFG this week to nearly 5,000.

Overall, she said Thursday was a better day, with many fewer dead animals found.

Nearly a dozen DFG employees and five boats have been involved in this week's effort, with most of the DFG staff coming from the Gray Lodge Wildlife Area near Gridley.

“I think they've done an outstanding job of collecting the ducks that are out there,” Shimek said Thursday evening.

Shimek said DFG staff will conduct another “big push” Friday morning to collect more birds, but that they believe they've addressed most of the “hot spots” – places where high numbers of birds were found dead.

The Gray Lodge staff will then return home over the weekend, with Shimek and other local game wardens, aided by volunteers, continuing the effort.

If necessary, she said, the Gray Lodge staff will return next week to continue pickups.

DFG reports that avian cholera isn't dangerous to humans, but it is common this time of year.

The agency reported avian cholera is a common disease of North American waterfowl that results from infection with the bacterium Pasturella multocida. It spreads rapidly from bird-to-bird and can kill thousands of birds in a single incident. A bird infected with avian cholera dies quickly.

Avian cholera die-offs in waterfowl commonly occur during the winter months in California, especially during cold spells and fog, according to a DFG statement.

Dan Yparraguirre, Department of Fish and Game (DFG) wildlife biologist, reported that California and many other states experience waterfowl die-offs from avian cholera annually.

“California is the winter home and migration area for over 60 percent of the waterfowl that winter in the Pacific Flyway,” he explained. “The Midwinter Waterfowl Survey indicates that between four and six million waterfowl occur in California, making this state, particularly the Central Valley, one of the most important wintering areas for waterfowl in North America.”

Dense concentrations of birds enhance the transmission of the bacteria which spreads rapidly through bird to bird contact, contact with secretions, or ingestion of contaminated food or water.

Cold weather and high concentrations of waterbirds create ripe conditions for incidents of avian cholera, which has surfaced in two other areas of the state so far this winter – at Butte Sink Wildlife Management Area (Colusa County) and Merced National Wildife Refuge (Merced County) – in addition to Lake County, DFG reported.

Though avian cholera does not affect humans, people should avoid contact with any sick bird or animal.

Signs of sickness from avian cholera in birds include a sudden die-off of many birds; lethargy; convulsions; swimming in circles; throwing the head back between the wings; erratic flight, such as flying upside down or trying to land a foot or more above the water; mucous discharge; soiling or matting of the feathers around the vent, eyes or bill; pasty, fawn-colored or yellow droppings, and blood-stained discharge.

DFG reported that average annual loss of migratory birds to disease in California is about 25,000 birds; those figures are for birds picked up and disposed of, and the actual losses are greater.

Overall, avian cholera doesn't appear to be the greatest threat to California's wild birds. In 2005, the last full year of available data from the National Wildlife Health Center, of the nearly 12,000 birds picked up in California, most diagnosed causes of mortality were: petroleum spills (5,000); salmonellosis (2,400); botulism (1,800) and starvation (1,500).

With the avian cholera diagnosis, Shimek said DFG is giving people the go-ahead to dispose of any dead birds they find. They remind anyone picking up the animals to wear gloves and put the birds in plastic bags.

Once collected, the birds can be buried or Shimek can be called at her office, 275-8862, to pick up the animals.

However, she said if anyone finds more than a few dead birds in any particular area, they should call her to report a potential hot spot.

E-mail Elizabeth Larson at This email address is being protected from spambots. You need JavaScript enabled to view it..

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