Bird flu sparing piping plovers -- for now

Mar. 26—EMPIRE — Bird flu already claimed a bald eagle in Sleeping Bear Dunes National Lakeshore, and researchers are watching for its spread as they await the arrival of another winged seasonal resident — piping plovers.

Although the Centers for Disease Control and Prevention marked 2022 as the first re-emergence of the H5N1 strain of highly pathogenic avian influenza since 2016, for Great Lakes piping plovers it was a record year for raising chicks since they were listed as endangered in 1986: 150 among the 72 unique pairs of the pint-sized shorebirds, according to the National Audubon Society.

The highest concentration of those birds choose Sleeping Bear Dunes, where 32 miles of shoreline and two islands — especially North Manitou's long, isolated southern point — provide lots of habitat. Vince Cavalieri, the national lakeshore's wildlife biologist, said he expects the year's first arrivals in three weeks.

No piping plovers died of influenza in 2022, he said. That's good news, as even a single death could have serious consequences for the Great Lakes population, and avian botulism already has felled nine over the years.

"So given the small nature of the population, we're of course worried about (bird flu) and on the lookout for it," he said.

Researchers place leg bands on these closely watched birds as part of a recovery effort that spans numerous state and federal agencies, universities, nonprofit groups and even two zoos where foundling chicks are raised, according to the Great Lakes Piping Plover Conservation Team.

To quash the chances of cross-contamination, those banding teams are taking precautions like washing hands, sanitizing equipment and cleaning "banding boxes" used to handle the birds, Cavalieri said.

More drastic measures like vaccinating piping plovers against the flu aren't being explored yet, but they're not out of the question either. There's some precedent from when U.S. Fish and Wildlife Service considered distributing botulism antitoxin to veterinarians in the Grand Traverse region to treat any of the shorebirds infected by a type E avian botulism outbreak.

That outbreak, luckily, faded although it hasn't completely gone away, Cavalieri said.

"There have been drastic measures like that taken into account and, if we were to start seeing some issues with avian flu, I think that would quickly be explored," he said.

While the U.S. Department of Agriculture licensed some vaccines against H5N1 avian flu, they can only be used when approved by federal and state animal health authorities, according to the American Veterinary Medical Association.

Vaccines against any highly pathogenic avian influenza can only be used in an official USDA control program.

There's not much else that can be done to protect wild birds beyond trying to slow the spread, even for other threatened or endangered species like the Kirtland's warbler, said Megan Moriarty, wildlife veterinarian for the Michigan Department of Natural Resources.

No bird flu has been detected in Kirtland's warblers, but their tiny size and fairly small numbers means it would be difficult to find one and send its carcass for testing, she said.

Banning any feeding of wild birds is unlikely, as the DNR recognizes how much people value being able to view wildlife, she said. The agency could issue recommendations that people take their feeders inside in the case of a bad outbreak.

With highly pathogenic avian flu being as widespread as it is, Moriarty agreed that anyone who can't regularly clean their feeders should keep them inside.

There were more than 160 detections in wild birds since the start of the latest outbreak, beginning with a mute swan collected in Monroe County in March 2022, according to the DNR. Five of those were in Grand Traverse County, one in Antrim, one in Benzie and one in Kalkaska.

Wild migrating birds are suspected to have brought the disease to the state, Moriarty said. They can spread the disease to domesticated birds, although human infections are extremely rare — the only human detection in the U.S. so far is believed to be the result of a person having contaminated matter in their sinuses, according to the CDC.

"Migratory birds are driving the outbreak, but it's just so widespread at this point it's involved a lot of players," she said.

The flu is devastating to poultry producers, impacting more than 57 million birds. That forced the destruction of entire flocks and drove up the price of eggs and chicken.

In the wild, it wreaked havoc on waterfowl like ducks and geese, Moriarty said — Cavalieri said it also damages other threatened birds like common and Caspian terns, which nest in colonies.

That tendency to group gives the illness a chance to spread from infected birds, Moriarty said.

Dabbling ducks and other waterfowl also can serve as a reservoir for bird flu, since they can carry the virus without getting sick or develop infections without symptoms, according to the CDC. Compare that to chickens, which suffer at least 90 percent mortality and often within 48 hours.

Ducks and other waterfowl susceptible to bird flu share some overlapping habitat with piping plovers, Moriarty said.

That trait, plus plovers' tendency to stake out and even fight over nesting territory, could be one way piping plovers could catch the disease from wild birds and spread it to their neighbors, he said.

But another trait could work in piping plovers' favor: their tiny size. Moriarty said controlled laboratory experiments have shown that while larger waterfowl, raptors and scavenger birds are more susceptible to the virus, smaller birds aren't as much.

Yet the virus was found in a handful snowy plovers in California, so there's reason to believe piping plovers are susceptible, she said — the two species are very closely related, Cavalieri said.

"I think it's an important point that animals that are already facing a lot of threats from other diseases or habitat loss or destruction are just more vulnerable to kind of drastic impacts from disease outbreaks that perhaps more robust populations could kind of bounce back from," Moriarty said.

Bald eagles now number more than 300,000 after facing extinction in the 1960s, going from 416 known nesting pairs to 71,400, according to the American Eagle Foundation.

Bird flu has killed the large, charismatic birds of prey and caused nest failures and drove an "unprecedented number" of positive detections for the virus, Moriarty said. She pointed to a study showing a possible link between these mortalities and a larger impact on their populations.

Other raptors with recovering numbers are falling to the disease as well, like peregrine falcons.

What these deaths mean for their long-term populations is hard to say in the midst of an outbreak, she said.

It's also hard to say what will happen with a virus that could mutate to become more infectious, or less so.

"I think it's unclear what the future will hold, but I think we're learning a lot from this outbreak and we'll hopefully be able to apply it to the next one," she said.

For now, Cavalieri and others involved in restoring the Great Lakes piping plover are hoping their luck holds, and that the virus doesn't take hold among these tiny shorebirds.