“We found silence and massive numbers of carcasses,” says Marcela Uhart, a wildlife veterinarian at the University of California Davis who has worked in Argentinian Patagonia for about 35 years. “All ages, new and old, just piled up on the beach where there should have been living, happy animals.”
Many of the animals still gripping to life were pups—clearly ill, and apparently alone.
“When the tide came in, as we were leaving the beach, some of those pups were actually in the water, unable to get out, and drowning,” says Uhart. “And these are elephant seals. They don’t drown.”
Back at the lab, samples confirmed the outbreak of highly pathogenic H5N1 avian influenza. Uhart and her team estimate the virus killed 17,400 pups, or approximately 96 percent of all young born in 2023. As with people, such severe cases of the virus can cause systemic organ failure and neurological issues.
The virus proliferated in seabirds that scavenged on the carcasses. At one point, she says, there were so many dead terns lying around that seagulls began using their corpses as nesting material.
Uhart was also an author on a report that found shocking numbers of wildlife deaths due to bird flu in South America. Between October 2022 and November 2023, the virus has killed nearly 600,000 birds of at least 82 species and more than 50,000 mammals of at least 10 species, mostly in Peru and Chile.
“We have never seen anything like this before in South America or Antarctica,” says Uhart.
Bird flu in poultry
While the virus has spilled over into wild mammals in North America, from bobcats and bottlenose dolphins to gray seals, coyotes, and skunks, and myriad birds, from bald eagles to mallards and great horned owls, there haven’t been any equally gruesome mass casualty events on that continent—yet.
The U.S. Department of Agriculture keeps running tabs on positive tests. For instance, between February 5 and 26 of this year, scientists detected avian influenza in wildlife in 15 states, from California to Florida to Maine.
At the same time, more than a dozen states have also confirmed infections in poultry flocks, both backyard and commercial, affecting more than 90,000 birds. That’s still a small number compared with the more than 9.5 billion broiler chickens and 208 million turkeys processed each year in the U.S., says Shilo Weir, a spokesperson for the USDA’s Animal and Plant Health Inspection Service.
“It is also important to note that we saw fewer cases of [bird flu] in 2023 than we did in 2022,” Weir says in an email.
This decrease may be due to tighter biosecurity measures, which prevent spread from farm to farm, she says. Fewer detections may also mean that “there’s less virus in the environment,” says Weir.
Lack of solutions
As for what can be done to stop bird flu, so far, the answer appears to be: not much.
While experts have experimented with vaccinating wild and critically endangered California condors against the virus, the logistics of vaccinating other populations, wild or domestic, have yet to be worked out.
“It’s not off the table,” says Lane, “but trying to vaccinate a colony of gannets would just blow my mind.” (Read why birds matter, and are worth protecting.)
Uhart says vaccines could be protect some wild animals, but that controversies around human health have thwarted those products’ development.
“At this point, I find it increasingly unacceptable that we’re willing to kill billions of chickens around the world to control a disease that we could manage differently,” she says.
Meanwhile, the virus will continue to spread, adapt, and evolve into new forms—some of which may be more targeted at mammals, including us, says Uhart.
“This is a number one zoonotic disease,” she says, “and a virus that has every single trait that makes it perfect for pandemic spread.”
