Thirty years ago, Jeffrey Worrell was working as a fly fishing guide in the Driftless Area when he spotted a chocolate brown raptor among the coulees.
It was a golden eagle, an elusive species in Wisconsin, unlike bald eagles. Worrell was certain.
“I’d called people I knew at the Department of Natural Resources and said, ‘You guys, I just saw a golden eagle,’” Worrell recalled. “And they said, ‘No you didn’t, Jeff. You saw an immature bald [eagle].’”
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Worrell argued back and forth with the DNR, urging them to send someone out to see what he insisted was a golden eagle.
For a while, nobody believed Worrell’s sightings.
Finally, in 2022, Worrell got a call from the executive director at the Raptor Resource Project in Decorah, Iowa, who believed he’d seen golden eagles — and wanted to fund research on the eagles’ population in the Midwest.
Worrell said there has not been much research golden eagles in this area. The Raptor Research Project has pointed to some work done in the 1960s and 70s.
“Very, very little is known about them and what they do here, why they’re here,” Worrell said.
Worrell joined WPR’s “The Larry Meiller Show” to talk about what his research has taught him about golden eagles.
Trapping golden eagles to learn about migration, ecology and immunology
The Raptor Resource Project’s golden eagle research is led by Worrell and raptor biologist Brett Mandernack. They’re tracing what the eagles do in their summering and wintering grounds.
Plus, the scientists are following the migration patterns of the eagles as they return to the Driftless Area each year, sometimes to the same coulee.
There’s never been immunology or virology studies done on golden eagles, Worrell said, and the area of research is especially important as bird flu continues to affect wild birds.
Worrell’s research suggests that golden eagle chicks can develop immunity to some of the strains of bird flu, similar to what’s being found in other raptors. Worrell said the reason eagle chicks have the disease’s antigen in their bloodstream might be because they eat infected prey.
To do all of this work, the researchers need to trap and “backpack” the golden eagles. The backpacks are lightweight GPS solar-powered transmitters, and they allow the team to follow the movements of each bird. Their goal is to backpack 25 birds and continue following the eagles for 10 to 15 years.
“They are incredibly smart birds. For example, when we trap we can’t be anywhere near the area that we trapped in [before],” Worrell said. “If we are, they know it, and they won’t even fly over the valley that we’re in. We’ve learned that the hard way.”
The Raptor Research Project team trapped six golden eagles this year. They belive two of the eagles to be a mated pair, Worrell said. And one of them was the oldest living golden eagle in North America. Worrell said the bird was banded in Pennsylvania some 33 years ago.
The life of a golden eagle
The golden eagles Worrell is studying mate and nest above Hudson Bay. Then, the eagles fly down to the Driftless Area of Wisconsin, Iowa and Minnesota to winter.
“They can take the cold. Ten below doesn’t even faze them. They’ll just sit and yawn all day long. They don’t care,” Worrell said. “They are absolutely amazing in what they can deal with, as far as environmental conditions.”
The raptor eats mostly medium-sized mammals and birds. A plump wild turkey is simply irresistible to these “supreme predators,” Worrell said.
Once, a bow hunter just north of Wabasha contacted Worrell. His trail camera had captured an 11-pound golden eagle bringing down a 140-pound deer.
The next morning, Worrell and the hunter looked at the deer carcass. By then, it was a block of ice. The eagle had eaten a little and left a lot for the coyotes, crows and mice.
Mature golden eagles grasp a deer by the head when they’re hunting, Worrell said. Their powerful talons crush the deer’s skull, killing it instantly.
Golden eagles more often target deer without the intent to kill, Worrell said, and it looks like they’re harassing the deer.
“They will chase deer and grab onto their derrières and ride them like a bucking bronco,” Worrell said. “Then they’ll let go and fly off, and then come and do it again, over and over.”
Sighting golden eagles
It can be easy to confuse a golden eagle for an immature bald eagle, especially against a sunny sky.
Bald eagles and golden eagles are roughly the same size.
Of course, adult bald eagles’ heads are white and golden eagles’ heads are brown. But in addition to that, Worrell said there are a few dead giveaways when it comes to differentiating between the adults.
Golden eagles have refined heads, smaller beaks and a golden nape. In contrast, Worrell said bald eagles have “a big old Jimmy Durante snoot.”
Telling apart young eagles is trickier, specifically because young bald eagles’ heads are dark, like the golden eagles.
Young golden eagles stay pretty dark as they grow, though you can see some white feathers where the wing connects to the body and on the tail. Young bald eagles have similar coloring, but it’s not as stark white.
A juvenile golden eagle has a big white band across the tail, which will darken as it ages.
Editor’s note: This story was updated Monday, March 24 to reflect that the Raptor Resource Project pointed to some work that was done to study these eagles decades ago.
If you see a golden eagle in the Driftless region of Wisconsin, Minnesota or Iowa, contact the Raptor Resource Project by calling or texting Jeffrey Worrell at 651-212-3026 or reaching Amy Ries at amy@raptorresource.org or 612-237-5793.
