MINNEAPOLIS — Rising numbers of great-horned owls, bald eagles and red-tailed hawks have been getting sick and dying of bird flu this winter as the virus continues to mutate and circulate in North American wildlife.

There are no signs of this strain of the H5N1 virus dissipating, unlike past bird flu outbreaks. Wildlife managers are bracing for the possibility that it may become a permanent part of the landscape.

“It may be here to stay,” said Dana Franzen-Klein, the medical director of the Raptor Center in St. Paul.

The Raptor Center treats sick and injured birds found throughout Minnesota. The center has tested every animal it has taken in for avian influenza since early 2022, when the outbreak reached the state. That first year was the worst. The center handled about 200 birds then, mainly convulsing eagles and dazed great-horned owls, that died of the virus in spring 2022.

Then cases slowed to a trickle.

Just a handful of injured birds brought to the center from fall 2022 to late 2024 tested positive for the flu. In a hopeful sign, most of the birds treated over those two years actually had antibodies for the virus, showing that either they or their parents had contracted it and recovered, and that some immunity was building up in the wild.

But in November, a dying great-horned owl brought to the center tested positive. Then a bald eagle, and then a red-tailed hawk. Over this past winter, a total of 21 birds of prey tested positive for the virus, the most since the early months of the outbreak.

The rising cases in St. Paul coincided with die-offs of hundreds of migrating Canada geese and ducks in southern Minnesota, eastern Wisconsin, Illinois, Missouri and Indiana.

Waterfowl and shorebirds are better adapted to the virus than raptors and other scavengers and can often carry it without symptoms, Franzen-Klein said.

So when the virus kills off large numbers of waterfowl, it typically signals a new mutation that makes it more harmful to its hosts, she said.

Raptors typically get sick by eating or scavenging the infected meat of ducks and geese.

The virus has wiped out some smaller populations of eagles and owls in certain areas, but, overall, raptor populations in the state seem to be holding steady, said Seth Goreham, a wildlife research manager for the Minnesota Department of Natural Resources.

“Since 2022, we’ve seen some localized comments about bald eagles taking a hit,” Goreham said. “Especially over in the Lake Michigan area populations may be down. But we haven’t seen anything in Minnesota, at least, that would indicate there was a major population hit.”

The priority for the monitoring and surveillance of bird flu has centered on poultry and livestock. Since 2022 the flu has either killed or forced the culling of about 150 million domestic birds, including more than 9 million in Minnesota. The U.S. Department of Agriculture has paid turkey and chicken farmers more than $2 billion for their losses.

The virus began infecting cattle last spring, and dairy farmers now regularly test for it in milk. Nationally, one person has died from H5N1 and more than 60 people have contracted it, mostly from infected dairy farms. There have been no known cases of the virus spreading from person to person.

The more the virus spreads and circulates in the wild, the more paths it has to infect farms and turkey operations and the more chances it has to mutate, epidemiologists warn.

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