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Understanding the Bird Flu Threat

Birds in birdbath
Bird flu testing

Avian influenza, commonly known as the bird flu, is a viral infection that primarily affects birds and occasionally spills over into other species, including mammals. According to the World Health Organization (WHO), there are multiple strains of avian influenza, with H5N1 and H7N9 being among the most dangerous.  These strains are responsible for Highly Pathogenic Avian Influenza (HPAI), which can cause up to 100% mortality in bird flocks in as little as 48 hours.  As of 2023, bird flu has spread to 81 countries across five continents, infecting both wild and domestic bird populations as well as up to 26 species of land and aquatic mammals. The global death tolls are alarming; 131 million poultry birds either died or were culled due to exposure in 2022 alone.  That same outbreak cost the US government over $661 million in livestock loss payouts.  

The effects on wild bird populations are harder to calculate, unless birds are brought into a wildlife rehabilitator for testing.  In 2023, nearly 9,000 wild birds were confirmed to be infected with HPAI in the United States alone.  The virus has recently been detected in pet cats, who likely acquire it by preying on infected birds. Bird flu has been found in at least 26 species of mammals, though there are on-going studies to better understand the routes of transmission.  Even more alarming, the virus has also been known to spread to humans.  Over half of the nearly 900 people infected with avian influenza died, between 2003 and 2021.

Bird Flu infographic
Bird flu statistics

Within bird populations, either wild or domestic, the spread of the diseases is well understood.  Like a sick human, birds shed the virus through saliva, feces or other bodily excretions, which then come into contact with and infect healthy animals.  So far, the majority of infections in humans have come from direct contact with infected domestic poultry and not through person to person communication.  When a wild bird passes away, scavenger animals consume it, and nearby areas are contaminated by infectious excretions to be picked up by the next living thing.  As the virus passes through a flock of birds and into new species, the chances for mutations increase.  Research into vaccines is being conducted, as poultry plays a major part in the US economy.  So far, raising awareness of the risks, close monitoring and strict reporting regulations are keeping outbreaks under control.

If you're an avid birdwatcher who enjoys feeding feathered visitors, make sure to clean your bird feeders regularly. Disinfecting feeders and baths weekly with a diluted bleach solution will help prevent the transmission of the virus among birds.  Consider removing bird feeders and baths during periods of reported outbreaks.  This typically occurs in the spring and fall when natural food sources are readily available to the birds.  If you see a sick bird with any discharge coming from nares (nostrils) or eyes, report it immediately to your regional wildlife or agricultural department and alert your local wildlife rehabilitator.  While there are no designated treatments available, a rehabber may be able to help manage symptoms, or at least end suffering.  Ideally, the infected animal is removed from the area as soon as possible to prevent it from infecting others.

By understanding the gravity of the situation and taking proactive measures in our own homes, we can contribute to the broader efforts aimed at preserving the well-being of our feathered friends and the diverse array of species that share our planet. In the face of adversity, collective action and individual responsibility, we can pave the way for a healthier, harmonious coexistence with the natural world.

Birds in bird bath
Birds at bird feeder
Birds in pond

Ariyama, Naomi, et al. “Highly Pathogenic Avian Influenza A(H5N1) Clade Virus in Wild Birds, Chile.” Emerging Infectious Diseases, vol. 29, no. 9, 1 Sept. 2023, pp. 1842–1845,, Accessed 13 Dec. 2023.

CDC. “Past Reported Global Human Infections with Highly Pathogenic Avian Influenza A(H5N1) (HPAI H5N1) by Country, 1997-2022 | Avian Influenza (Flu).”, 19 Apr. 2022,

CDC. “Technical Report: Highly Pathogenic Avian Influenza A(H5N1) Viruses.” Centers for Disease Control and Prevention, 5 Oct. 2023,

Centers for Disease Control and Prevention. “Avian Influenza in Birds .” CDC, 2019,

WHO. “Ongoing Avian Influenza Outbreaks in Animals Pose Risk to Humans.”, 12 July 2023,

Wikipedia Contributors. “Avian Influenza.” Wikipedia, Wikimedia Foundation, 26 Oct. 2019,​

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