West Nile Virus Kills Condor Chick

A California condor has died of West Nile virus, officials said Tuesday, confirming a new threat to the government’s 20-year effort to restore the high-soaring vultures to the wild.

A 3-month-old chick died Aug. 25, shortly after biologists retrieved it from a nest near the Hopper Mountain National Wildlife Refuge in northern Ventura County, said Marc Weitzel, a condor recovery project leader.

Testing at the San Diego Zoo confirmed that the chick was infected with West Nile virus, Weitzel said. Of 125 condors living wild in three breeding populations across western North America, only the Ventura County chick is known to have been infected, he said.

The other breeding populations are in Arizona and Baja California, Mexico.

With the chick’s death, however, federal and state biologists say they will expand an inoculation program begun two years ago to protect the remaining flocks.

“We’ve been concerned that the virus could hit the program, and now it has,” Weitzel said.

Biologists until now had only vaccinated adult condors, said Jesse Grantham, a biologist with the U.S. Fish & Wildlife Service. Testing of captive condors had shown that maternal immunity is passed on to chicks, he said.

But biologists were unsure how long the protection lasted, and the recent death indicates that it is for a short time. The dead chick’s parents had been inoculated twice, in June 2003 and June 2004, Grantham said.

Instead of waiting until chicks grow into fledglings, biologists will now try to vaccinate them soon after they have hatched, he said.

Just two or three chicks are hatched each year in Ventura County’s backcountry, Grantham said. Though the birds are constantly monitored with remote cameras, getting to them can involve a helicopter ride and a strenuous hike, Grantham said, adding that the effort is well worth it.

“If even a couple of birds are hit by the virus, it is serious because it’s such a small population,” he said.

West Nile virus emerged in the United States as a threat to humans, horses and birds in New York in 1999 and has traveled west, infecting about 15,000 people and killing almost 600. Transferred by mosquito bite, the virus can cause flu-like symptoms, pneumonia and even death in humans.

Dead infected crows are often the first sign that the virus has arrived in a community, health officials said.

Federal and state efforts to revive the condor species have been hampered by the birds’ inability to cope with the spread of civilization.

The scavengers have soared over mountainous areas since prehistoric times but nearly died out in the 1980s because of their proclivity for eating things that kill them.

In the late 1980s, the seven condors remaining in Ventura County were taken captive for a breeding program. In 1992, biologists began releasing them back into the wild.

Biologists are aiming to increase the breeding populations in California and Arizona to 150 birds each.

Condors are now breeding in the wild again, though the program continues to suffer setbacks from chicks that ingest trash, glass, antifreeze and a variety of other things.

West Nile “is a new risk factor,” Weitzel said. “But I’m confident that with a more aggressive vaccination program, we can deal with it.”