By Karl Puckett
Great Falls Tribune
WHITE SULPHUR SPRINGS, Mont. — Golden eagles, hawks and falcons are zooming over Montana along mountain ridges taking advantage of powerful updraft winds during their annual fall migration to warmer climates.
“If you’re not looking for it, you’re not going to notice it,” said Steve Hoffman, executive director of Montana Audubon, the bird conservation organization.
One place to see the action is south of Duck Creek Pass in the southern end of the Big Belt Mountains in Helena-Lewis and Clark National Forest 19 miles west of White Sulphur Springs.
More golden eagles are using the Big Belts flyway during fall migration than any other location in the Lower 48, Hoffman says.
“Damn. You have to love it,” Hoffman said at the site Monday.
He was peering through a $3,500 pair of binoculars, watching a northern harrier, a type of hawk, swoop overhead. He could have seen the bird with the naked eye it was so close.
By day’s end, 70 birds of prey were counted, including 31 golden eagles.
It was a slow day.
Through the last Monday of September, 973 birds, including 431 golden eagles, had been counted since Sept. 1.
Migration comes in waves, Hoffman noted.
“It’s probably going to be the best golden eagle site in the Lower 48,” Hoffman said of the numbers that are being counted in the Big Belts.
And the public can witness the traffic at the rare bird bottleneck because it’s not difficult to reach the mountainside location where two observers are counting the birds as part of a golden eagle migration survey.
The accessibility to a major raptor migration route is rare, too, Hoffman said.
“We’ve had them at 20 yards,” Ronan Dugan said.
It’s the second year for Dugan, who is from Scotland, working as a raptor migration observer. Pay is $50 bucks a day. He lives in a camper with a leaking roof and hikes up the mountain to work each day.
Golden eagles are the most common travelers, but all kinds of raptors fly through, from vultures to osprey to northern goshawks.
“This is our office,” said Dugan, his arm gesturing to the sky.
For him, one of the most amazing parts of the job is viewing immature bald eagles, with white still on their wings, that were on the nest just a few months ago in Canada and Alaska.
Dugan and co-worker Jeff Grayum scan the sky with binoculars, or the valley below.
It’s their job to count every raptor they see. They also attempt to determine the age and sex.
Montana Audubon is partnering with Montana Fish Wildlife and Parks, the U.S. Forest Service and Last Chance Gulch Audubon, in the migration survey, which began in 2015.
The primary objective is to measure long-term population trends of golden eagles using the Big Belt Mountains flyway.
“Look at that. Oh, boy,” says Pat Grantham, a birder from Clancy who drove a four-wheeler up the mountain to spend the day watching birds.
It’s a golden eagle.
“Another bird down low,” Grayum announces, alerting the others to another raptor that’s flown into view.
The bird-watching bivouac is at an elevation of 8,340 feet.
That’s high enough that bird-watchers sometimes look down at the birds.
In Montana, 17 species of diurnal raptors, which are active during the day, are known to migrate through the state or spend time here.
Every one has been documented in the Big Belts, but golden eagles are the undisputed stars in the sky because of their size. As adults, they weigh 9 to 14 pounds with wingspans of 6½ feet.
Crows that occasionally chase them look like songbirds by comparison.
“We’re not talking about pigeons here,” Hoffman said.
Golden eagles are considered “charismatic fauna” because of their widespread popular appeal, just like wolves, elk or grizzly bears, Hoffman says.
They can reach speeds of 100 mph when they dive, tucking their wings and falling like rocks to surprise prey such as jackrabbits, ground squirrels and occasionally a wild turkey.
“They’re representative of wild places,” Hoffman said.
For the past 25 years, one of the most important places for monitoring migrating golden eagles in the western United States has been the Bridger Mountains, northeast of Bozeman and 60 miles south-southeast of the Big Belts.
The most significant outcome of the long-term study was a 40 percent decline in counts of migrating golden eagles along the flyway since the late 1990s.
That decline stopped around 2010, Hoffman said, but it’s still important to keep an eye on the population because raptors are excellent environmental indicators because they are sensitive to habitat change.
The estimated golden eagle population in North America is 80,000 to 100,000, with most of the birds located in western North America.
In Montana, they are listed as a “species of concern.”
“Only in a few places do they migrate through those very narrow corridors,” Hoffman said.
The spine of the Rocky Mountains is a general migration corridor for raptors traveling from Alaska and Canada to the southwestern United States and even Mexico, Hoffman said.
Orographic lift occurs along the Rockies. That’s when air is forced from a low elevation to a higher elevation as it moves over rising terrain.
“They can just fly hundreds of miles without flapping,” Hoffman said.
Lift from the mountain winds allows the birds to conserve energy and reduce their caloric intake during the migration, Hoffman said.
“They’re more dependent on ridge lift, strong ridge lift, than any of the raptors,” Hoffman says of golden eagles, which expend more energy hunting than smaller, nimbler raptors.
Constriction points are located along the general migration route, and the Big Belts is one of those areas.
Birds follow ridge lines.
And the Big Belt Mountains are a relatively isolated range, oriented along a northwest to southeast axis, with a single, narrow ridge line, as opposed to multiple ridge lines that would give the birds more than one route to travel.
“It leads the birds into a narrow funnel,” said Hoffman, comparing the mountain range to an hourglass.
Persistent, strong southwesterly winds, presumably due to a “lake effect” from Canyon Ferry Reservoir, also buffet the mountains.
Employees with the Raptor View Research Institute in Missoula first noted the high number of raptors when they were banding some golden eagles south of the Big Belts. They passed along the information to Hoffman.
In 2014, Hoffman, Dan Ellison, a member of the Helena City Commission and an avid birder, and Ellison’s wife, Jane Fournier, took a look.
“The birds just kept coming,” Ellison said.
In six-and-a-half hours, they counted 284 golden eagles.
Ellison called it a once-in-a-lifetime day.
Based on that experience, an abbreviated counting season was conducted over 47 days in 2015, and observers saw 4,318 raptors, including 2,630 golden eagles.
It was the highest passage rate for golden eagles of any of the Rocky Mountain migration sites south of Canada, suggesting the Big Belt Mountains flyway would be a prime location for studying the movements and population.
All 17 species of diurnal raptors in the state were observed — in a single day, on Sept. 23.
On Oct. 7, 392 raptors, including 329 golden eagles, were counted.
More golden eagles were counted in the abbreviated 2015 season than the combined number of golden eagles counted at four other locations in Montana where migrating raptors are monitored.
The first full season of counting in the Big Belts was launched this year beginning Sept. 1. It will continue until Nov. 5.
Peak migration will occur over the next few weeks.
On a recent Monday, five people were hunkered down with binoculars and cameras, sun screen slathered on their faces and stocking caps covering their heads on the exposed face of the mountain.
Grayum and Dugan are on the job from 10 a.m. to 6 p.m. daily.
It’s not easy to identify some of the quick-moving birds that seem to appear out of nowhere.
“They don’t come back for a second look,” said Ellison.
Some of the birds are drawn to the spot by a decoy of a great-horned owl posted at the top of a white-bark pine, its head swiveling in the wind.
Even though the raptors are just passing through, they have a strong instinct to chase the owl away because great-horned owls are their No. 1 enemy. At night, owls will pick off raptors on the roost or take their chicks from the nest.
At 2:25 p.m. Hoffman asked for a bird count. Just then, the northern harrier swooped in. Also known as a marsh hawk, it weighs less than a pound and has a 3- to 3 /2-foot wing span. It lives on valley bottoms and marshes. Here it was soaring in through the Montana mountains.
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