Do golden eagles range into Central Minnesota?

The confirmation, capture and tagging of a golden eagle observed and netted at Camp Ripley earlier this month broadens researchers' idea about what might constitute the range of a raptor previously thought of as a West Coast species.

Part of the reason they've gone undetected: Mature golden eagles look a lot like juvenile bald eagles, unless you know to look for — the gold at the nape of the neck, feathers all the way to the toes, the white band on the underside of juveniles' wings.

"This bird up at Camp Ripley opens up that part of the state," said Scott Mehus, education director at Wabasha's National Eagle Center. The Golden Eagle Project grew out of his observations of golden eagles nesting in the bluffs near Wabasha. "Now that we've got this knowledge base, people are going to start looking more critically."

The female golden eagle was captured March 10 at Ripley. It's the latest of six to be outfitted with a transmitter, and one of three still transmitting. On March 11, it was outfitted with a backpack and released. The solar-charged battery lasts about six years.

The bird's migratory movements are recorded every hour; routes appear on the National Eagle Center's website, www.nationaleaglecenter.org. What researchers find, Mehus said, might inform habitat-related decisions such as where to preserve land. The first step is to define that habitat, range and migration pattern.

In the bluffs, golden eagles tend to hunt small mammals — rabbits, squirrels, wild turkeys, mostly, and the occasional small deer — in open areas such as the steep goat prairies. It's unclear if the golden eagles at Camp Ripley are regulars and what sort of habitat they're using.

Golden Eagle Project co-director Mark Martell, director of bird conservation for Audubon Minnesota, said the most pressing question the transmitters will answer is where the birds are going.

Eagles captured to date have migrated in Canada as far east as the Labrador Sea and as far west as Great Slave Lake.

The cost is $3,500 per transmitter and $1,000 per year to download the information. Funding comes from the Legislative-Citizen Commission on Minnesota Resources.

Martell was at Camp Ripley when a co-worker handled the bird. Neither wore gloves; both have worked at the University of Minnesota's Raptor Center. Part of the secret: Never let your muscles untense.

"Golden eagles are so strong that if (one) wanted to rip into you, it could," Martell said.

The capture at Camp Ripley involved a remote-triggered net and trail cameras, and followed two winters' worth of observing the raptors descend upon deer carcasses meant to attract the wolf packs biologists are tracking. It's likely to sharpen the observations of Central Minnesota birders who might not have considered the raptors they were seeing could be goldens, not balds.

Even on National Eagle Center-led bus tours, the golden eagles can be hard to spot as they perch among oaks, maples and basswoods.

"They're not at the end of the branch," said Eileen Hanson, public relations director at the National Eagle Center.

The 2015 Wintering Golden Eagle Survey counted 137 golden eagles from Red Wing to southern Iowa.

Mehus isn't the only one watching anymore. The NEC and Audubon Minnesota are partners in the tracking effort. Before the Camp Ripley capture, the most recent tagging took place during the 2012 migration at Duluth's Hawk Ridge Bird Observatory. That eagle winters in southern Missouri.

Last fall, Mehus got a call and trail-cam photos from Brian Dirks, a Camp Ripley-based Minnesota Department of Natural Resources animal survey coordinator who confirmed what trail cameras showed: The feeding eagles were goldens.

"What we really don't know is if this is their home range," said John Maile, natural resource manager in Camp Ripley's environmental office. "What are they doing here? How long are they here? Is this really their wintering area?"

Follow Ann Wessel on Twitter @AnnWessel.