Vaccinating Condors Against HPAI

Oakland Zoo
April 19, 2024

The current strain of highly pathogenic avian influenza (HPAI) is the largest HPAI epizootic (animal version of an epidemic) event in the nation’s history. But what is its origin? It is believed that direct exposure to wild birds has led to increased transmission, with peaks occurring in the spring and fall migrations of wild birds.

In April of 2023, 20 condors died in the Arizona-Utah flock. Upon investigation, it was discovered that the highly pathogenic avian influenza (HPAI) was the cause of death for 10 of those birds. Due to the endangered status of the condors and the threat to their survival, the U.S. Fish and Wildlife Service, in collaboration with the USDA, decided to approve a vaccine previously not allowed in the U.S. The vaccine was approved on an emergency basis to help preserve the condor recovery program. This week, the condors who live at California Trail received their second dose of the HPAI vaccine.

Vaccinating a California Condor at Oakland Zoo

To help you understand more about the vaccination process and condor conservation, we’ve created this FAQ:

How does HPAI affect birds?

HPAI is highly contagious, and once contracted, it can affect multiple organ systems and possibly lead to sudden death. It can wipe out entire flocks in a matter of days.

Can humans get sick from HPAI?

The disease is spread through infected birds' saliva, mucous, and feces. Although it is rare for humans to be infected with HPAI, humans have contracted the disease after having close contact with infected birds.

How many vaccines must be administered? Will the condors need to get a booster?

Two doses of the vaccine are administered three weeks apart. We expect the need to administer a booster annually, but that is still yet to be determined.

Is the vaccine experimental, or has it been tested before?

The vaccine was tested last year in coordination with the U.S. Fish & Wildlife Service (USFWS), USDA, and U.S. Geological Service, starting with black vultures at the Carolina Raptor Center, then later with California condors at the Los Angeles Zoo, San Diego Zoo Wildlife Alliance, and Oregon Zoo.

Are there any side effects of the vaccine?

Several condors at other locations have had mild vaccine site reactions that have been resolved.

Will the USDA approve free-flying condor vaccinations?

USDA approved free-flying condors to be temporarily taken into captivity to receive their vaccinations. The Ventana Wildlife Society and Pinnacles National Park just began HPAI vaccinations of wild condors in central CA.

How have Zoos helped aid in condor conservation?

1982 California condors were listed under the Endangered Species Act as critically endangered. By 1986, the last wild California Condor was taken into captive care, leaving only 27 remaining. Luckily, an alliance of organizations and zoos came together to conserve, breed, and release these giants into the wild, halting the extinction of a magnificent species. This alliance is named the California Condor Recovery Program, of which Oakland Zoo is a proud member.

As a member of the Condor Recovery Program, what does Oakland Zoo do for condor conservation?

Field biologists train Oakland Zoo's veterinary and animal care staff to provide medical care, including lead chelation therapy, to wild condors deemed ill or injured. The Zoo’s veterinary staff is also actively involved with biologists in the field and at major universities, collaborating on projects to better define the threats to condors and find solutions. Oakland Zoo also supports the lifesaving work of Ventana Wildlife Society through grants and by providing monthly supplemental food for wild condors in Big Sur, California.

California Condors at Oakland Zoo