SHIRLEY BASIN—Mike Lockhart has been patrolling this vast sagebrush sea for hours, driving county roads and stopping at vantage points to glass for raptors as they ride aloft early afternoon thermals.

The abundance of white-tailed prairie dogs and their pups provides easy pickin’s for the golden eagles, turkey vultures, ferruginous hawks and other raptors that flourish here along with pronghorn, black-footed ferrets, greater sage grouse and swift fox. That’s good for the raptors, Lockhart said, but not so good for his chances of trapping and tagging a golden eagle.

“It’s been a really tough year for trapping so far,” Lockhart said as he peers through binoculars.

Lockhart, a wildlife biologist who worked for the U.S. Fish and Wildlife Service for 33 years, is conducting field research on golden eagles in the region for the U.S. Geological Survey and Conservation Science Global in anticipation of expanding wind energy development. He’s live-trapped and tracked more than 180 federally protected bald and golden eagles in Wyoming and Colorado since 2014. Each bird provides vital information that can help federal wildlife officials determine where wind turbines might threaten local eagle populations and other raptors migrating through areas considered for wind energy development. 

Wildlife biologist Mike Lockhart monitored live-traps he’d set hoping to capture a golden eagle in the Shirley Basin north of Medicine Bow. (Dustin Bleizeffer/WyoFile)

But Lockhart worries that the vital data from field research is emerging slower than encroaching wind turbines in southern and south-central Wyoming. Federal wildlife managers that can determine where and how wind energy facilities are configured to avoid threatening eagle populations are relying too much on modeling to fill in gaps between actual data, he claims.

“The data is just inadequate for making these [permitting] decisions,” Lockhart said.

On this June day, Lockhart feels a growing sense of anxiety about his chances of adding to the body of science. He drives on, spots several raptors swooping down on targets other than his traps, and curses.

Overlapping resources

Wind energy developers have erected hundreds of new wind turbines in south-central and southeast Wyoming in recent years. The state has more than doubled its wind energy output since 2019 by erecting more turbines and replacing others with larger electric-generating capacities.

The growth is not expected to slow. Wind energy in Wyoming could more than double from its current capacity of 3,000 megawatts by 2030, according to those close to the industry. The expansion, which energy experts believe may even accelerate further under the Inflation Reduction Act, could pose a serious threat to eagles and other wildlife in certain areas without field-data-driven information to guide avoidance and mitigation strategies, according to Lockhart.

Wind turbines just west of Wyoming Highway 487 north of Medicine Bow. (Dustin Bleizeffer/WyoFile)

Of particular concern, he said, are proposed wind energy projects that will essentially fill in yet-to-be industrialized areas, such as the Maestro wind energy project in the Shirley Basin. Carlsbad, California-based Maestro Wind LLC proposes to construct up to 327 wind turbines spanning nearly 99,000 acres that straddle Highway 77 here. The project area essentially encompasses the heart of the Shirley Basin’s eagle habitat, according to Lockhart. 

In a September 2021 preliminary filing to the Bureau of Land Management’s Rawlins Field Office, the company said it will rely on existing eagle data and conduct its own pre-construction surveys and analysis.

This map depicts the extent of the proposed Maestro Wind Energy project in the Shirley Basin north of Medicine Bow. (TRC, Fort Collins)

If done correctly, with enough field data, the project could be designed to avoid critical nesting sites and high-traffic “flyways,” Lockhart said. But more data is needed, and permitting authorities must insist it guides the project design.

“This is probably one of the best places, that I know of anyway, for golden eagles in North America,” Lockhart said. “I am a big wind energy advocate and definitely a green energy supporter. But we can’t devastate one really critically important resource for another.”

Maestro has yet to file an official permitting request with the BLM and other permitting authorities. The company didn’t respond to WyoFile inquiries. To move forward, the BLM, which manages more than 80% of the project area, must conduct a full National Environmental Policy Act analysis with public comment. 

The Maestro project isn’t the only wind proposal that worries Lockhart. 

“I’m equally concerned about the ones that might impact breeding birds and kind of fill in those gaps between the existing wind [energy facilities],” he said.   

Luring eagles

Lockhart had set two traps earlier in the day, using dead jackrabbits and a live “lure-eagle” tethered between them. Wildlife officials sometimes collect eagles that are injured and cannot be successfully released into the wild. This lure-eagle, a golden that Lockhart uses in his field research, is “on loan” from the Comanche Nation in Oklahoma. 

“I am a big wind energy advocate and definitely a green energy supporter. But we can’t devastate one really critically important resource for another.”

Mike Lockhart, wildlife biologist

Normally, the sight of two rabbit carcasses and a lure-eagle seemingly inspecting a prospective feast would easily tempt other eagles into an aggressive bid for a meal. But there is no shortage of prospective meals to be had on this day. 

In addition to the bounty of live, scurrying mammals, a pair of nearby shooters have been plunking prairie dogs with rifles for a few hours, adding to the buffet. Lockhart worries the recreational shooters, in addition to distracting eagles away from his traps with freshly killed prairie dogs, might be seasoning the prey with lead shrapnel — a particular threat to eagle populations.

A meteorological tower next to Wyoming Hwy 77 provides vital information to wind energy developers about wind speeds. (Dustin Bleizeffer/WyoFile)

Like most wildlife, eagles are hard-wired to take advantage of a situation — even wholly unnatural and potentially fatal ones, Lockhart said, such as feasting on lead-poisoned carcasses or roadkill on a busy highway. It’s not that wind turbines with blades 80 yards or longer are invisible to eagles in flight, he said, it’s that eagles and other raptors are often more focused on scanning the landscape for sustenance than scanning their flight paths for giant, slicing blades. 

On this day, though, with no wind turbines for many miles, Lockhart is counting on an eagle’s intuition to take advantage of an unnatural situation he’d created — for the sake of conservation.

Through field glasses, he watches a golden eagle land and approach one of his rabbit carcass traps about 2 miles away. A few moments later, a tethered white, plastic grocery bag puffs out above the eagle’s head — the signal Lockhart had been waiting for all day.

He coaxes his labrador Emma into the truck and starts driving. 

Eagle data

How much data there is about eagles in Wyoming and their relation to existing and proposed wind energy projects depends on what you’re looking for.

Wind energy developers, in the pre-construction federal and state permitting process, typically borrow from existing data on local nesting sites and eagle populations and hire consultants to conduct new surveys in the field. But that information isn’t typically compiled in a way that allows for a comprehensive count or region-wide database that could be used to analyze potential cumulative impacts.

Although the Wyoming Game and Fish Department reviews and comments on wind energy proposals in federal permitting, it doesn’t conduct comprehensive eagle field surveys and mostly defers to federal wildlife authorities, according to Public Information Officer Sara DiRienzo. 

A turkey vulture swoops in the Shirley Basin north of Medicine Bow. (Dustin Bleizeffer/WyoFile)

“There is a growing concern especially with raptors, such as the golden eagle or the ferruginous hawk, that there may be population impacts, especially when you look at locations that have multiple wind farms,” DiRienzo said. “Understanding the cumulative effects is still ongoing and not conclusive at this time.”

In addition to pre-construction avoidance planning necessary to obtain a permit for wind energy construction, the U.S. Fish and Wildlife Service works with “willing wind energy developers” to minimize and mitigate impacts during normal operations, FWS Public Affairs Specialist Allison A. Stewart said.

The motivation to “willingly” work with federal and state wildlife officials to avoid eagle-turbine collisions is to also avoid fines for killing the federally protected species. ESI Energy Inc., and its affiliate NextEra Energy, for example, were fined $8 million in April for killing more than 150 eagles in several states over a 10-year period, including at wind facilities in Carbon and Laramie counties.

The companies failed to acquire federal “incidental take” permits, which can protect operators from running afoul of the Migratory Bird Treaty Act. Incidental take permits are voluntary but they require the permittee to take on conservation efforts that would negate incidental eagle kills, Stewart said.

PacifiCorp, the largest wind energy producer in Wyoming, has incidental take permits for most of its wind energy facilities in the state. The company’s incidental take permits for each of the Seven Mile Hill and Dunlap wind energy facilities in Carbon County allow for six to seven eagles per year, according to PacifiCorp spokesman David Eskelsen.

Every known eagle-turbine kill must be reported to the FWS, but the agency doesn’t compile up-to-date incidental take permit totals for the public, nor does it keep running tallies for the state or for particular wind energy facilities that are readily available to the public.

A bird in hand

At the trap site, the labrador Emma is relegated to the truck while Lockhart collects the bird. 

Lockhart uses a specially modified clamp-trap designed to secure itself around the eagle’s hallux, or back talon, without crushing or pinching. He releases the bird from the trap, binds its legs with wide cloth and strides back to the pickup with a sense of duty replacing what had been anxiety.

The talons of an adult male golden eagle were bound as wildlife biologist Mike Lockhart took blood and feather samples and fit the raptor with a GPS backpack. (Dustin Bleizeffer/WyoFile)

He hoods the wild specimen and drapes it in a towel to keep it calm before securing the lure-eagle in a large dog kennel in the backseat. As he climbs into the driver’s seat cradling the eagle in one arm, he turns the radio volume up. It’s a distraction to help subdue the wild animal, he explains. 

Lockhart drives a few miles to find a good location to band, sample and fit the eagle with a GPS backpack. On the way there, the radio blares “Poor, Poor Pitiful Me” by Linda Ronstadt and “Witchy Woman” by … the Eagles.

The strategy works. The eagle remains subdued, and Emma — accustomed to her master’s eagle research work — appears to care less about the giant raptor.

Field biology

Lockhart sets up an impromptu work station consisting of a tailgate, folding table and tackle boxes full of equipment a couple dozen yards off a county road, where the biologist can keep an eye on his single remaining trap a couple miles away.

Wildlife biologist Mike Lockhart displays the plumage of a young adult male golden eagle he trapped and released in June 2022 in the Shirley Basin. A bespoke GPS backpack has been affixed to the bird. (Dustin Bleizeffer/WyoFile)

He already knows he captured an adult male golden eagle. Next, he weighs the bird (3.78 kilograms, or a little more than 8 pounds). Then Lockhart splays it on a comfy dog pillow, keeping most of its body draped with a towel to convince it that it’s being held down.

Lockhart plucks several feathers (the bird doesn’t flinch) and slides them into small, labeled envelopes before taking a blood sample. 

“It has excellent plumage,” Lockhart said. “It’s in really good shape.” 

He crimps a metal band around one leg, deeming the bird Wyoming golden eagle #1228-00422. It is the 16th golden eagle Lockhart has trapped in Wyoming so far this year.

Then comes the most difficult part: constructing a tailor-fitted GPS backpack for the raptor. For this task, Lockhart uses ribbon material that can fit snug around its shoulders and chest without chafing. He sews the connections using special thread and a break-away knot — in case the backpack gets snagged or if eagle #1228-00422 ever decides he’s determined to scrape it off.

After about 40 minutes of meticulous tailoring, Lockhart snips and glues loose ends, then colors the GPS device with permanent markers to blend it in with the eagle. You don’t want other birds to notice the device, he said. Ravens and eagles are incredibly intelligent, noticing anything out of the ordinary, and they’re aggressive enough to pester even an adult golden eagle if they sense a vulnerability.

Wildlife biologist Mike Lockhart displays the wingspan of a young adult male golden eagle he trapped and released in June 2022 in the Shirley Basin. (Dustin Bleizeffer/WyoFile)

With the backpack complete, Lockhart takes several measurements (wings, tail, beak and head). He unhoods the eagle and asks the WyoFile reporter out in the field with him to release it. 

Golden eagle #1228-00422 takes flight, flitting low at first, a little disoriented. It flies higher and with more purpose, as a large raven swoops behind and shadows its every move.

A ‘floater’

Since it was captured and released on June 16, golden eagle #1228-00422, according to satellite tracking, has crossed the North Platte River several times, hung out on Casper Mountain, lingered around wind turbines north of Medicine Bow and returned to the Shirley Basin.

“It’s doing really well and moving around a lot,” Lockhart said. “It’s a floater, not a breeder.”

GPS data shows the movements of golden eagle #1228-00422 since it was captured and released on June 16, 2022. (Mike Lockhart)

The data from golden eagle #1228-00422, he said, suggests there are resident eagles occupying nests throughout the Shirley Basin and perhaps this eagle is content to float around the central area, taking advantage of a lot of good habitat until it gets a chance to breed and nest. 

What it tells prospective wind developers and wildlife officials is there’s a vibrant eagle population in the Shirley Basin. If done incorrectly, a wind energy facility here that regularly kills local eagles could create a “spiraling sink,” Lockhart said. That’s when year-round residents are killed and then replaced by migrating eagles that then face the same fate.

“We’ve been gathering a lot of information,” Lockhart said. “It’s just so valuable to what’s going on right now, and people need to make sure it gets analyzed and put into the management decisions.”

Dustin Bleizeffer is a Report for America Corps member covering energy and climate at WyoFile. He has worked as a coal miner, an oilfield mechanic, and for 25 years as a statewide reporter and editor primarily...

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  1. Seems it would be beneficial to developers and researchers and consultants for you to develop data gathering guidelines so data could be analyzed more easily. Also why does FWS not gather and make incidental takes public?

  2. Between 2009 and 2018, I was the Visitor Services Assistant for the Rocky Mountain Regional Office of the U.S Forest Service (R2 HQ) . During my ten years of service, I spent four of those years running a service counter inside the USGS Map Store on the Denver Federal Center (DFC). There, I met (and was befriended by) the USGS employee responsible for compiling “kill” and “take” data for the ‘Survey. His data, if revealed to the public, would have thrown professional conservationists and a large segment of the public into a frenzy over raptor mortality caused by wind turbine farms. On coffee breaks, he would complain to me that his supervisor was pressuring him to alter his data. Finally, upon returning from an Annual Leave, in 2012 or early in 2013, he discovered his data had been removed from his computer and he was rebuffed by his supervisor when he ask for its return! He was relieved of his assignment. He resigned. After the USGS Map Store on the DFC was closed, I was assigned to manage a portion of the Public Room operation in the BLM Colorado State Office. There, I met a Special Agent(SA) whose wife was an SA for the U.S. Fish & Wildlife Service. She allowed us a tour of the National Eagle Repository in Denver. There, I learned that the vast majority of the 3,000 to 4,0000 eagles parted-out each year were either killed by wind turbines or electrocuted. I retired in 2018. My “take-away” from that experience is that the various federal agencies, principally the USF&W Service, the DOE, the USGS, and the BLM, wage conservation information/policy wars with one another, the outcomes of which are totally dependent upon the political flavor of the day (not science) as determined by the federal executive and federal legislature in power at any given time. As Sgt. Friday used to say, “Just the facts, Maam.” But that was television; not the real world.

  3. There is data for this area. I was part of a team of biologists working for a consulting firm, that gathered raptor, breeding bird, prairie dog, swift fox data for the Shirley basin area. I spent 3 summers watching and recording information, about hawks and eagles, every single square mile of the project area. Multiple times every year and for over 3 years. Bird surveys were conducted. Even bats were inventoried. All of this was done for the project proponents, so that they could have information to present to the permitting agencies.

  4. In addition to smart siting, turbines can now be equipped with sensors which detect birds and brake/curtail turbine rotation. E.g. Identiflight out of Boulder CO, and others from the EU. The system from Boulder was installed and tested in Wyoming a few years ago and reduced eagle fatalities by three quarters at a windfarm where too many raptors were being killed.
    Combining both smart siting and this sensing clearly seems desirable.