MIKE MILLER

March is a month of migratory wonder. Waterfowl take to the wing and fly north along the Mississippi Flyway towards nesting grounds in the upper Midwest and Canada. Huge flocks of Snow Geese are a seasonal attraction at Emiquon Preserve and Chautauqua National Wildlife Refuge along the Illinois River just south of Peoria. Birds have developed many unique strategies for survival. Migration is one that offers many benefits, but it also poses several threats.

One of those threats is one that is relatively recent. Highly Pathogenic Avian Influenza (HPAI) is a highly infectious disease of birds. One strain of HPAI virus, known as Type A

H5N1, was first discovered in 1959. Since that time, the virus has evolved to become more effective in spreading. Unfortunately, its evolution has also made it very lethal to birds and other animals.

In 1996, a new lethal strain of this HPAI virus was identified in East Asia. In 2005, this strain was responsible for killing more than 6,000 wild birds of multiple species in Asia. Since that time, the HPAI virus has become a global phenomenon as it spreads throughout our planet.

Snow Geese take flight at Emiquon Preserve. If you go bird watching to observe the seasonal migrations, be advised to take precautions against bird flu.
DENNIS ENDICOTT/AUDOBON SOCIETY

One of its avenues of spread is migratory bird corridors. As birds gather and stage for migration, the pathway for spread becomes concentrated and the virus continues to evolve. Recent strains have left the reservoir of wild bird populations and jumped into domestic birds. One strain has become very lethal to poultry causing the need to euthanize more than 20 million egg-laying hens in the fourth quarter of 2024. That’s why egg prices have sky-rocketed recently.

Other strains of this virus have jumped from birds to mammals. Dairy cattle have become susceptible to their own strain of this virus. It can easily spread amongst cattle and affect milk production. Luckily, pasteurization of milk will kill the virus. Recently, we have seen the variant infecting cattle also able to infect people. Dozens of human cases have been identified and tied to exposure of infected cattle. As of this date, there is not a known infection caused by human-to-human transmission. However, if there’s one thing we shouldn’t underestimate, it is the ability of viruses to evolve and take advantage of new ways of spreading. Other mammals have also been reported dying from HPAI strains. In early 2024, more than 6,000 elephant seal pups died in Argentina as a result of HPAI exposure.

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HPAI virus strains are now a part of “our new normal.” We will need to adapt our agricultural practices to meet this new challenge. We can only hope that wild bird populations will build some type of immunity, or that the virus evolves to be less lethal to its host.

Bird migration is full of perils, unfortunately HPAI is a deadly one for our beloved waterfowl.