Avian influenza – Unprecedented Spread Among Wild Birds

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Brad Trumbo

Field Staff Writer at Harvesting Nature

Brad lives in southeast Washington State with his wife Ali and pack of Llewellin setters on a small homestead. He serves the public as a fish and wildlife biologist and active Pheasants Forever life member. His free time is devoted to habitat, the pursuit of fin and feather, and writing about his outdoor passions.

Latest posts by Brad Trumbo (see all)

• Rewinding the Kissimmee River - May 19, 2023
• Changing Grazing Behaviour Could Help Grassland Ecosystems - April 21, 2023
• Is Avian Influenza Infecting Mammals Cause for Concern? - March 17, 2023

Avian influenza, like most viruses, comes and goes in severity and transmissible with any given variant, but the U.S. is currently facing a record number of outbreaks. Meanwhile, the virus is spreading in France, the United Kingdom, and Korea.

The poultry industry is taking the brunt, having lost over 50 million birds in the U.S. alone, according to the U.S. Center for Disease Control (CDC). But what’s more concerning is the unprecedented spread in wild birds – greater numbers and a variety of species are susceptible to the current H5N1 variant compared to other variants, including species in extreme climates.

“Dozens of infected penguins in South Africa have died”, reported Saima May Sidik in Nature¹.

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The H5N1 variant is highly transmissible and may be spread widely by migratory waterfowl. The virus is spread through contact with an infected bird’s saliva, mucous, and feces.

Picture a lakeside golf course lawn speckled by 100 loafing Canada geese. The fecal load left by an infected goose flock in a single afternoon could present a viral minefield for any subsequent avian visitors, and presents a plausible example of how wild birds have tested positive in 46 U.S. States since early 2022.

While the H5N1 variant is behaving like a new strain, it is actually old news. It was first found in commercially-raised geese in Asia around 1996, and has repeatedly infected wild birds around the world since, reported Brittney Miller in Nature². The 2022 outbreak is unusually strong and appears to be moving uncontrollably through wild bird populations worldwide.

So, what’s the bottom line for wild birds? Scientists have made no speculation regarding the impacts of the virus to wild bird species or populations; however, this scenario does pose a potential extinction risk for currently imperiled water bird species.

The CDC suggests that wild birds including gulls, terns, and shorebirds, and wild waterfowl such as ducks, geese, and swans are considered natural hosts for bird flu viruses, and most wild birds infected with these viruses are asymptomatic³. Somewhat good news, but H5N1 “…has likely spread beyond the point of ever disappearing from North America again”, said Rebecca Poulson, a wildlife disease researcher with the University of Georgia College of Veterinary Medicine.

1 Why is bird flu so bad right now? (nature.com)

2 Why unprecedented bird flu outbreaks sweeping the world are concerning scientists (nature.com)

3 Current Bird Flu Situation in Wild Birds | Avian Influenza (Flu) (cdc.gov)