This blood sample comes from a migratory shorebird caught on the beaches of Delaware Bay in New Jersey. Each May, scientists funded by the National Institute of Allergy and Infectious Diseases, or NIAID, descend on these beaches to test shorebirds for the flu. “And we’re here at Delaware Bay–the hotspot for influenza, and it is an absolute gold mine.” Shorebirds stop on these beaches on their migration north to their breeding grounds in the Arctic Circle. They’re here to feast on the eggs of horseshoe crabs as they come ashore to breed. When the birds gather, they tend to swap influenza viruses more rapidly than when they’re isolated. “This area is particularly good because there’s a large abundance of birds. This is in fact the only place known in the world where influenza viruses are isolated at such a high rate from shorebirds.” In 1985, researchers from St. Jude Children’s Research Hospital began sampling shorebirds. In 2007, NIAID began supporting these efforts, which now involve scientists from St. Jude and the University of Georgia, through its Centers of Excellence for Influenza Research and Surveillance program, or CEIRS. As the birds congregate on the beach, the researchers trap them for sampling. They collect blood samples to monitor the health and influenza infection status of each bird. The scientists also gather throat swabs. “We don’t really know exactly why there’s such a high rate of influenza in these birds at this time. We just know that once the infection seems to start, then it spreads. So it’s kind of like a…this is like an incubator or a percolator or a generator for flu viruses.” To monitor the different viruses, the researchers also collect fecal samples from the beach. They pack up the samples carefully to transport them to the lab, where they will grow stocks of virus to conduct further tests. The virus isolates are stored in a repository and made available to other researchers. The test results are helping researchers learn more about how influenza spreads and evolves. The shorebirds’ flu is unlikely to infect humans, but it could potentially cross over into other species. Flu subtypes that can cause disease in domestic poultry rarely appear in shorebirds. “But we have to look. And then you never know… There are a few other subtypes which are on the watch list–the higher risk ones to humans.” Researchers are still unsure where and how new strains of flu emerge as the birds migrate and why they seem to infect certain species, like the ruddy turnstone, more than others. With further monitoring in the years to come, they hope that some answers will come to light.