Migrating Birds Tested in Avian Flu Early Warning System

CENTERVILLE, Md., Oct. 20, 2005 — -- It's a sight usually greeted with wonder -- millions of migratory birds heading south for the winter. But in California, scientists are keeping a wary eye on the skies.

Migrating birds are blamed for spreading the deadly avian flu virus to Siberia, Romania, Turkey and Greece.

"Clearly bird flu is on the move," said Dr. Walter Boyce, director of the Wildlife Health Center at the University of California, Davis. "Our concern is wild birds, as they migrate, might carry the bird flu with them."

Migrating birds have already spread the avian virus from Asia to Siberia. Birds are now migrating from Siberia to Alaska, down the Pacific Flyway, to the West Coast.

"As the virus spreads to new areas, the risk becomes higher and higher," said Dr. Carol Cardona, a veterinarian and UC Davis professor.

So researchers on the West Coast are trying to stay one step ahead. For the first time, they are taking throat and fecal samples from tens of thousands of wild birds.

"Our goal is to detect what viruses they are carrying and basically have an early warning that something might be getting ready to happen," said Boyce.

The samples are injected into developing eggs. If the embryo dies, scientists then determine which deadly virus is to blame.

The California Department of Food and Agriculture is conducting monthly tests for the avian flu at stores that sell live birds. Chicken farmers are also on guard.

In the mid-Atlantic area, farmers raised more than 500 million chickens last year. The industry takes disease precautions very seriously, and it starts at the farm gate. Visitors aren't welcome, and the chickens are confined inside, away from migratory birds.

"We feel that we're doing everything here that we need to do, hopefully, to keep it out from here," said poultry farmer Jenny Rhodes.

The Haley chicken farm in central California is one of a number of farms involved in prevention and detection networks.

"If one of our neighbors was to come down with the disease, we would be notified immediately," said poultry farmer Kim Hernandez.

Just last year, migrating birds infected some U.S. chickens with a less deadly form of the avian flu, which is why farmers and state officials are staying alert.

ABC News' Lisa Stark filed this report for "World News Tonight."