NYT Exposure to the virus is expected to rise as condors, an endangered species, migrate north in the spring, the National Park Service said.
At least three California condors in northern Arizona have died since last month from bird flu, which could spread and pose yet another threat to the endangered species, the National Park Service said.
Officials are trying to determine whether the virus was the cause of death for five other condors. Five additional birds that were captured exhibited signs of the illness, the Park Service said.
The condor — a scavenger bird with a 9½-foot wingspan — is an endangered species that has been protected by federal law since 1967 and by California state law since 1971.
Wildlife officials with the Peregrine Fund, which manages the Arizona-Utah condor flock, collected a dead female condor on March 20 that they first believed was sickened by lead poisoning.
A positive result for highly pathogenic avian influenza was confirmed by the U.S. Department of Agriculture’s National Veterinary Services Laboratory on March 30. Officials later confirmed that two other condors had died from the illness, a subtype of the flu.
The Peregrine Fund captured five additional birds that showed symptoms of illness and sent them to a wildlife rescue in Phoenix. One bird died shortly upon arrival. Its cause of death was not immediately clear on Sunday. Four others have been quarantined as they are tested, the Park Service said.
Test results were not yet final for five additional dead birds.
Signs of the illness in birds include lethargy, lack of coordination, holding the head in an unusual position and walking in circles, according to the Park Service, which said the highly pathogenic avian influenza has been detected in every state except Hawaii.
The California condor is the largest land bird in North America, native to large sections of the continent, from California to Florida and Western Canada to Northern Mexico.
By 1982, only 23 condors remained in the wild, according to the U.S. Fish and Wildlife Service.
Scientists believe that the species has been threatened by habitat degradation, lead poisoning from lead ammunition, and the synthetic insecticide DDT, which was banned in the United States in 1972.
To prevent extinction, scientists captured the remaining birds in 1987 to breed in zoos. The birds were later reintroduced to the wild in sanctuaries and national parks. By 2020, the population had grown to 504 birds.
The infected birds were part of a population that moves between northern Arizona and southern Utah, including Grand Canyon National Park, according to the Park Service. Officials expect exposure to the virus to rise during the condors’ migration north in the spring.
So far, the avian flu has not been detected in other condors in California or Mexico’s Baja California, the Park Service said.
The United States is experiencing its largest-ever outbreak of avian flu, which started early last year. It has affected more than 58 million farmed birds and has spread to mammals, such as minks, foxes, raccoons and bears.
The outbreak has prompted the Centers for Disease Control and Prevention to explore the development of avian flu tests and the White House to consider vaccinating poultry.
The virus poses a low risk to human health, according to the C.D.C., but infections in humans have previously been reported.
Avian flu is highly contagious in the wild and can spread quickly through bird-to-bird contact, environmental contamination with fecal material, and exposed clothing, shoes and vehicles.