Dead gull: Collecting swab sample from a deceased Great Black-backed Gull on Nantucket Island, Massachusetts. The sample was processed by the Runstadler Lab at Cummings School of Veterinary Medicine at Tufts University and found to have High Pathogenicity Avian Influenza. Photograph by Wendy Puryear.

Perhaps you noticed the steep increase in the cost of eggs in the summer of 2022, or followed the plight of the Charles River Esplanade swans that fell ill that year. Perhaps you know of a nest of eaglets that needed to be rehomed when both parents were found dead at the base of the tree, heard of a Northern Gannet colony in Atlantic Canada with significant reproductive loss in 2023, saw an unusual number of dead Canada Geese and seabirds along the North Shore of Massachusetts in early 2024, or have been cautioned recently against the consumption of unpasteurized milk. Did you know that a recent shift in Influenza A virus (IAV) is the common thread throughout all these events?

Commonly referred to as bird flu, H5N1, or High Pathogenicity Avian Influenza (HPAI), this virus seemingly has stormed onto the global stage over the past few years. It has decimated diverse wild bird populations, devastated backyard and commercial poultry, and is causing increasingly worrisome outbreaks in mammals. Despite the recent escalation, this virus comes with a long and complex history that is rooted in wild birds, shaped by agriculture, and has now expanded around the globe in unprecedented and unexpected ways, with the North Atlantic seemingly operating as a critical entry point to continued introductions of novel forms of the virus.