US officials on Tuesday announced the emergency use of an avian influenza vaccine to protect the California condor, a critically endangered and magnificent animal that has already bounced back once from the brink of extinction, Reuters reported.

After finding a California condor dead from highly pathogenic avian influenza, or bird flu, in March, the US Fish and Wildlife Service sought help from the US Department of Agriculture (USDA). Since then, at least 13 condors with avian influenza have died, USDA said in a press release.

The deaths, all near the Arizona-Utah border, are alarming considering the world population of California condors was estimated at 561 at the end of 2022, including 347 free-flying birds in three western states and Mexico and 214 in captivity, according to the US Fish and Wildlife Service.

Before condors are vaccinated, the wildlife service will conduct a pilot safety study starting this month on North American vultures, marking the first time the vaccine has been tested on wild birds in the United States, said Joanna Gilkeson, a wildlife service spokesperson.

Avian influenza has killed hundreds of millions of birds worldwide, with the virus largely spread by wild birds that transmit it to poultry.

While scientists work on poultry vaccines, commercial flocks for now are protected by other measures such as segregation, USDA said.

The California condor is one of the world's largest flying birds with a wingspan of up to 9 feet (2.7 meters) and weighing more than 20 pounds (9 kg), according to the California Department of Fish and Wildlife.

The population was reduced to a few dozen birds by the 1970s because of illegal killing, lead poisoning, poison bait and environmental pollutants such as the pesticide DDT.

But a captive breeding program helped increase the population to 161 birds by 1999 from 27 in 1987, the state department said.