By CHRISTINA LARSON AP Science Writer
WASHINGTON (AP) — Bird flu has devastated poultry and dairy farms, and sent the price of eggs soaring in the United States since it was first detected in North America in late 2021.
But what has been the toll on wild birds? More than 170 species of North American wild birds – including ducks, geese, gulls, owls, eagles and others – have been infected with bird flu.
Take precautions around sick or dead wild birds, experts recommend. But you can keep your bird feeder up. Despite the spread in birds and other wild animals, scientists say the threat to the general population is currently low.
Which wild birds can get bird flu?
More than 12,000 individual birds have tested positive since the virus began spreading, according to the U.S. Agriculture Department.
The count is a “gross underestimate” because most dead birds are never taken to a lab for testing, said Bryan Richards at the U.S. Geological Survey’s National Wildlife Health Center in in Madison, Wisconsin.
Dabbling ducks, such as mallards and blue-winged teal, can carry the virus with few symptoms because “these viruses co-evolved in waterfowl,” said Richards. But ducks can also shed the virus in their feces or saliva, sometimes infecting other birds or mammals like foxes.
Birds without natural immunity that migrate or roost together in large flocks, such as geese, are most likely to die in large numbers. A recent bird flu outbreak among migratory eared grebes in Utah killed between 15,000 and 25,000 birds near Great Salt Lake, state wildlife officials said in early February.
Seabirds, which tend to roost in large numbers, are also highly impacted.
Songbirds such as Northern cardinals, blue jays or chickadees — the kind of birds that might visit bird feeders — can also become infected and die, but their populations appear to fare better since they don’t gather closely in large groups where the virus could spread, said Michael J. Parr, president of the American Bird Conservancy.
What are bird flu symptoms in wild birds?
Symptoms vary, but may include lack of coordination, inability to fly and respiratory distress.
“If people see a wild bird acting weird, the best thing they can do is call their local wildlife rehabilitator” and avoid handling it directly, said Dr. Dana Franzen-Klein, a veterinarian and medical director at the University of Minnesota’s Raptor Center.
If you must handle an infected bird, it’s best to wear gloves and a mask as a precaution.
Is it safe to have a backyard bird feeder?
Experts say bird feeders are generally safe and aren’t a notable source of spreading bird flu.
But if you also keep backyard chickens, Parr of the American Bird Conservancy recommends taking the bird feeder down to prevent possible transmission to poultry. Birdfeeders and nesting boxes should also be cleaned regularly.
The risk of spread to people from bird feeders “is very, very low,” he said.
How is the bird flu outbreak affecting endangered bird species?
In the case of critically endangered California condors, scientists organized a vaccination program after some birds became infected. But that’s not a realistic option for most wild bird species.
Instead, experts recommend giving wild birds the best chance by taking other steps to protect habitats and reduce various risks that species face, such as exposure to pesticides or lead ammo.
Bald eagles, which are federally protected but no longer endangered, are scavengers that will eat dead animals. “That first year, we lost a lot of eagles” likely from bald eagles eating infected ducks or bringing them to their nests, said Richards.
Scientists also documented an unusually high number of eagle chicks that didn’t survive into adulthood during the first breeding season after the virus appeared in North America, likely because the chicks got the virus or sick parents weren’t able to adequately feed and care for them.
But over time, the number of confirmed infections in eagles nationwide has declined from 427 in 2022 to 48 last year.
That may mean that eagles that survived the first year now have some acquired immunity, said Franzen-Klein. This past migration season, researchers counted a record number of bald eagles migrating through northern Minnesota.
“There are good signs of hope” that eagles in the region are rebounding, she said.
___
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.
