Avian influenza killing far fewer birds this year – Duluth News Tribune

DULUTH — The strain of highly pathogenic avian influenza that ravaged wild birds and some mammals across Minnesota and Wisconsin in spring 2022 appears to have diminished this spring, with far fewer birds perishing.

Minnesota still leads the nation with the most birds reported dead from the H5N1 strain of influenza, but the number of birds reported so far this year is just a fraction this year of what it was in 2022, according to data from the U.S. Department of Agriculture.

Some biologists had predicted that wild birds would either build up resistance to H5N1, which appears to have happened, or that the strain would mutate and become an even worse killer. So far that has not happened.

Avian influenza “did not show up this past spring in the virulent way it did during the 2022 outbreak in both wild and domestic birds, thankfully. It does seem that there have been wild birds shown to build up an immunity to the strain … which is very likely why we didn’t get a lot of reports of morbidity/mortality,” said Eric Hildebrand, wildlife health supervisor for the Minnesota Department of Natural Resources.

Minnesota is up to 607 wild birds confirmed dead from H5N1. But 566 of those were from the first 12 months that the disease was present, roughly from spring 2022 through late winter 2023. Since April, only about 40 additional birds have been confirmed dead from the disease as the second wave of migrating waterfowl returned from their wintering grounds. That’s a more than 90% reduction in reported cases.

Wisconsin has 216 total cases in wild birds, up by only five additional birds this spring.

Only a fraction of the birds that actually die from H5N1 are ever found and tested, but it’s likely still a good indicator of any trends and the reduced impact.

Contributed / Robert Dusek / U.S. Geological Survey

In Minnesota, the DNR, U.S. Fish and Wildlife Service, wild bird rehabilitation centers and others collect fresh carcasses, responding to reports of sickly or dead birds. But no single agency is keeping track of how many are found and sent for testing by the other agencies. We only know how many positive results come back from the federal laboratory in Ames, Iowa, where testing occurs.

“Our Wildlife Health Program was responding to any reports by the public or from our staff of any bird seen alive and neurologic or if an event of five or more dead/dying birds were reported,” Hildebrand noted. “We did have a few cases of these happen and carcasses were collected, but, again, not the volume of reports like we saw in 2022.”

Minnesota also has confirmed H5N1 cases in several mammals, including skunk, black bear, red fox and fisher but no cases in humans.

H5N1 was present in Minnesota throughout the winter and some studies showed their disease has the ability to survive very cold water temperatures even without a host animal.

Nationally, more than 7,000 wild birds have been confirmed dead from the virus over the past 18 months, but that’s only up about 500 in recent months after 6,500 were reported in the first year of the outbreak. Birds in all 49 continental states have died, led by waterfowl and the raptors that eat waterfowl such as eagles and hawks.

Songbirds rarely contract the disease and experts say no additional precautions are needed for people who feed birds. According to the National Wildlife Disease Program, there is currently “low risk of an outbreak among wild songbirds,” and there is no official recommendation to take down feeders — unless you also keep domestic poultry on your property. Experts do recommend that you clean bird feeders and birdbaths regularly as a way to keep several kinds of bird diseases at bay.

The disease seems to flourish most in the spring, with most deaths reported in Minnesota from March into May. Species impacted in Minnesota include crows, pelicans, bald eagles, barred owls, broad-winged hawks, Canada geese, common goldeneyes, loon, ravens, Cooper’s hawks, dark-eyed juncos, great-horned owls, hooded mergansers, mallards, northern harriers, red-shouldered hawks, red-tailed hawks, Ross’s geese, rough-legged hawks, snow geese, trumpeter swans, turkey vultures, white-fronted geese and wood ducks.

The most recent Minnesota case was confirmed June 2 with a bald eagle in Aitkin County perishing from H5N1.

Contributed / USDA

You’ve probably noticed the price of eggs and chicken have come down in recent weeks, thanks in part to a vastly diminished impact of avian influenza on domestic poultry flocks.

In May 2023, the USDA reported zero commercial poultry detections. There has not been a case of avian flu in commercial poultry since April 19 or in backyard poultry since May 18, 2023. That’s good news after H5N1 ravaged some 840 commercial and backyard flocks, killing or foreign the destruction of nearly 59 million poultry over the past 18 months.

John Myers reports on the outdoors, natural resources and the environment for the Duluth News Tribune. You can reach him at [email protected].