Bird flu is infecting and killing great horned owls and bald eagles in unprecedented numbers, according to Dr. Victoria Hall, executive director of the Raptor Center at the University of Minnesota.

"Entire families of owls are dying, parents and chicks," she said in a recent phone interview. In raptors, this virus is about 90 to 100% fatal, she said.

Eagles and owls prey on ducks, a potential source of infection. The virus is carried on talons to the nest, where it infects babies. Owls can pass the virus in their feces and respiratory secretions for days before showing signs of illness.

A bald eagle flew off with a mallard duck in its talons after diving into the waters of the Mississippi River. Waterfowl like ducks are a potential source of infection for raptors like eagles.
David Joles, Star Tribune, Star Tribune
A bald eagle flew off with a mallard duck in its talons after diving into the waters of the Mississippi River. Waterfowl like ducks are a potential source of infection for raptors like eagles.

Shed by ducks, the virus can linger in wet, cool environments, infecting birds after the waterfowl move on.

"By the time we see the infected birds they're in extreme neurologic condition. They are having severe seizures. The kindest thing we can do is euthanasia," Hall told me.

The virus is being found all over the state and country right now. It's very unusual to have an outbreak this widespread, this much infected wildlife in so many geographic locations, Hall said. "It's truly unprecedented."

In 2015 bird flu killed 9 million chickens and turkeys in Minnesota. Dr. Pat Redig, cofounder of the Raptor Center, was testing every raptor that came into the center, Hall said. Redig also was doing massive testing of ducks in the wild. He did not find a single positive result, she said.

"We know that the current virus came in with migratory waterfowl," Hall said. "Historically, we've seen transmission continue until hot weather in the summer months, when some of the migratory birds move on."

The center is not accepting dead birds anymore, she explained, because the virus security risk is so high. The staff wants to keep the center's education birds safe, and to be able to keep accepting other ill or injured birds at this time.

"It's really rare for this virus to go to people, but this time the chance is not zero. We're giving a whole lot of advanced guidance to people," Hall said.

She doesn't want people handling dead or infected wildlife and taking contamination home to their own birds, to chickens or pet birds, she said.

The Raptor Center is encouraging people to not touch any injured or dead wildlife they see. They should call the Raptor Center (612-624-4745) or the Department of Natural Resources (651-296-6157).

"If people want to rescue birds, we want them to understand all the precautions, what to wear, how they should protect themselves," Hall said.

Will this disease affect future raptor populations?

Colleagues around the country and the Raptor Center staff are trying to figure out how to look into this, she said. Historically, they've seen raptors die from highly infectious viruses. It's not unheard of, she said.

"But seeing breeding pairs and offspring dying, that's when it starts to make you very curious about what impact this could have," she said. "We're only touching the first number of diseased birds. There are a lot more in the wild that we're not counting."

What happens next? "We're in such a need for data and information about what's happening right now," she said, "that it's hard to predict."

Hall said they do know that this will be a short-term event. Increases have been seen in past springs, she said, when migratory birds come through. There usually is a significant slowing of infection in summer months.

(Note: The Raptor Center's previous guidance on it being OK to leave up backyard bird feeders has not yet changed.)

But so much wildlife is infected now, she said, there is the possibility this will pop up again in fall migration.

Raptor Center staff wear protective gear when handling infected birds.
The Raptor Center, Star Tribune
Raptor Center staff wear protective gear when handling infected birds.

"We've got our care team stretched to the max. We're in full hazmat suits, goggles and gloves as we work with these very sick birds.

"Complete nest failure really makes me very, very sad. Nobody around here has seen such a profound event before.

"We're not strangers to infectious diseases," she said. "We went through the West Nile infections. But this highly pathogenic avian flu is a different beast."

And, she said, "We're just getting started."

Lifelong birder Jim Williams can be reached at woodduck38@gmail.com.