Sunday, April 09, 2023

U.S. Fish & Wildlife Service Statement: HPAI Confirmed As Cause Of Death For 3 California Condors

California Condor - Photo Credit Don Graham


The critically endangered California Condor - whose population had declined to just 23 known survivors by the early 1980s due largely to the effects of DDT, lead poisoning, and a loss of habitat - has made a remarkable recovery due to conservation efforts by the US Fish & Wildlife Service, the National Park Service, and breeding programs at San Diego's Wild Animal Park and the Los Angeles Zoo

Today, more than 500 Condors exist in the wild, but now they face a new threat; HPAI H5N1.

As scavengers, Condors feed almost exclusively on carrion, which increasingly runs the risk of being infected with HPAI H5 (see USDA Mammalian HPAI Infection List).  On Friday it was announced that 3 Condor deaths have been attributed to H5N1, and an additional 5 are under investigation. 

First the press release from the US F&WS, then I'll return with more on how the food chain may impact the evolution of HPAI H5. 


Highly Pathogenic Avian Influenza Confirmed as Cause of Three California Condor Mortalities in Arizona

Additional birds deceased, others under care and quarantine with signs of illness

Apr 7, 2023

Media Contacts

Joanna Gilkeson

Marble Canyon, Arizona – Highly Pathogenic Avian Influenza (HPAI) has been confirmed as the cause of mortality for three California condors found in northern Arizona, according to wildlife officials. The Arizona-Utah population moves throughout northern Arizona and southern Utah, using the landscape within Grand Canyon National Park, Zion National Park, Vermillion Cliffs National Monument, the Kaibab Plateau, and surrounding areas. To date, the virus has not been detected in the other condor populations in California or Baja California, Mexico. 

On March 9, The Peregrine Fund, which manages the Arizona-Utah condor flock, first observed a bird in the wild exhibiting signs of illness, initially suspected to be lead poisoning. Crews continued to monitor this bird and others showing similar behavior. On March 20, they collected the deceased female below her nest, which was the first bird confirmed positive with HPAI.

Upon collection, the bird was went to the U.S. Fish and Wildlife Service’s Clark R. Bavin National Fish and Wildlife Forensics Laboratory for necropsy to determine the cause of death. Oregon Veterinary Diagnostic Lab analyzed samples, and preliminary results indicated the bird tested positive for HPAI subtype H5N1. The positive result was confirmed by the U.S. Department of Agriculture’s National Veterinary Service Laboratory on March 30.

As of April 4, a total of three deceased birds have been retrieved and confirmed as HPAI positive. Test results are not yet final for five additional deceased birds. Others have been collected and are pending necropsy and testing; information will be provided once test results are available.

Additionally, five birds displaying signs of illness were captured by The Peregrine Fund and sent to Liberty Wildlife in Phoenix, Ariz., for care. One of the birds died shortly after arrival. The remaining four are in quarantine while samples are tested for HPAI. Any additional live or deceased condors collected in Arizona and Utah will be treated as HPAI suspected cases. Live birds will be transferred to appropriate facilities to receive care.

California condor populations face multiple stressors, such as exposure to lead shot and habitat degradation, that have reduced the resiliency of the population. To address the unfolding threat of HPAI, coordination is ongoing with avian influenza experts, veterinarians, and Tribal, state and federal partners across the condor’s range. California condor recovery partners are mobilizing resources and taking preemptive steps to protect wild birds from HPAI. Across the condor’s range, daily activities continue, such as captive breeding and the monitoring of breeding and nesting sites.

Potential exposure of HPAI is expected to rise during the spring migration of birds north to their breeding grounds. HPAI has been detected in all U.S. states, except Hawaii, in wild and domestic animals.

HPAI is considered low risk as a human health concern, according to the Centers for Disease Control; however, infections in humans have been reported. HPAI is highly contagious in wildlife and can spread quickly by several routes, including bird-to-bird contact, environmental contamination with fecal material, and via exposed clothing, shoes and vehicles. To protect people and birds, it is important to take precautions to prevent spread of the virus.

Ways to help

  • If you see a condor exhibiting any of the following signs of illness in Arizona or Utah, please contact The Peregrine Fund at 585-747-5885. Signs include lethargy, incoordination, presenting as dull or unresponsive, holding head in an unusual position, and walking in circles.
  • Please follow the below guidance to help limit the spread of the virus and avoid bird-human contact: 
  • To report dead or sick animals, please contact your state wildlife agency.
  • Keep your family, including pets, a safe distance away from wildlife.
  • Do not feed, handle or approach sick or dead animals or their droppings.
  • Always wash your hands after working or playing outside.
  • Prevent contact of domestic or captive birds with wild birds. 
  • Leave young animals alone. Often, the parent animals are close by and will return for their young. For guidance on orphaned or injured wild birds, please contact your nearest wildlife rehabilitation center, state wildlife agency, or local land management agency. 
  • USDA also has biosecurity guidance for people who keep backyard poultry.

While the increased number of spillovers of HPAI to mammalian hosts is concerning, the `saving grace' has been that we've seen very little evidence of mammal-to-mammal transmission of the virus (possible exceptions being farmed mink and marine mammals)

This is considered important - particularly with zoonotic diseases like avian flu - because long chains of infection can lead to adaptive mutations, which can make the virus even better suited for a specific host. 

This is the basis for the classic `serial passage experiment' depicted below.   

While not nearly as efficient as airborne mammal-to-mammal transmission, the food chain in the wild can mimic the serial passage experiment above, and convert a `dead-end infection' into a link in a longer chain. 

A domestic cat eats a sick bird, then falls ill and dies. Its carcass is consumed by a coyote, which eventually dies, and is picked at by raccoon, which dies and is eaten by a bobcat . . . . 

You get the idea; instead of dying with its host, new mutations or host adaptations are given another opportunity to build upon their earlier gains. Serial passage obviously isn't guaranteed to produce a more dangerous virus, but it does provide the virus with more opportunities to reinvent itself. 

While many people are rightfully concerned about gain of function (GOF) experiments in laboratories around the world, a functional equivalent may be going on unseen in the woods behind your house.

When you consider the thousands of marine mammals that have died from H5N1, the millions of infected chickens and turkeys that have been disposed of, the millions of wild birds that died unseen in the wild, and a growing number of infected terrestrial mammals being detected, there are unprecedented levels of H5N1 virus in the environment. 

Which is why pet owners need to take extra precautions (see NVDC Report: 2 Domestic Cats Infected With HPAI H5N1).

 And the world needs to get (and stay) prepared for additional surprises.