RAWLINS -- In a small trailer on wind-swept prairie near Rawlins, a scientist sits and watches a computer screen. Outside, a large machine arm churns, releasing radar waves up to 3 miles above and 5 miles away, searching the sky for birds.
This site is expected to eventually be home to a 1,000-turbine wind farm, situated on 100,000 acres, about half federal land and half private.
When finished, Power Co. of Wyoming's Chokecherry and Sierra Madre Wind Energy Project is expected to be one of the largest in the country.
Braving the wind and the snow, another scientist about a mile from the trailer watches the sky, waiting for a radio call saying that a blip of color has shown up on the computer screen so she can scan the horizon to identify the flying mass.
The work is so monotonous, at times the scientists play solitaire in the heated trailer. But the work is considered cutting edge and it provides data that could help solve an issue only recently coming to the forefront in wind energy development: How can wind turbines avoid killing birds, specifically highly protected golden eagles?
Wind far boom builds concern
Wind farms are often touted as producers of environmentally friendly energy. In recent years, Wyoming has seen a boom in wind energy development with about a dozen more projects in planning stages.
Developers do seek to mitigate disturbances and deaths of animals, including sage grouse. But one of the biggest quandaries for those developers is the degree to which wind farms hurt federally protected golden eagles and how that damage can be decreased.
Right now the federal agency works with developers to limit development in crucial habitat as a way to mitigate effects on birds. But once a turbine is placed, there is little that can be done to alleviate bird deaths, said Trish Sweanor, a U.S. Fish and Wildlife Service biologist.
"We're trying to help 'green' energy get established, while also conserving avian populations," she said. "We don't want to trade one problem for another. It's difficult because it's so new and we haven't really had to deal with this type of fatality issue."
The Fish and Wildlife Service is working on an eagle conservation plan that calls on developers to work with the service from the beginning of a project, when assessing sites, through post-construction with monitoring.
The document is currently used to help organizations on a voluntary basis. The document is expected to be finalized by the end of the year, Sweanor said. The goal is no net loss of the eagle population.
The plan will be a crucial tool as Wyoming adds wind energy projects, Sweanor said.
Eagle collisions with wind turbines has been an issue for a while, said Pamela Murdock, planning and environmental coordinator with the Bureau of Land Management in Rawlins. The issue became more urgent in the past few years as more wind energy projects got under way.
Radar helpful, but not a full fix
Power Co. of Wyoming, the Chokecherry and Sierra Madre developer, is the first major wind project developer on BLM land to use avian radar to avoid killing birds, Murdock said.
Although nobody requires that wind developers use such radar, Power Co. of Wyoming decided to operate one. It could provide valuable data, for both agencies and the company, about bird populations and behavior in the area, Murdock said.
Power Co. of Wyoming began using the avian radar this spring, said Nathan Wojcik, an ecologist and environmental specialist with SWCA Environmental Consultants.
The firm is Power Co. of Wyoming's primary environmental and ecological consultant for the project, helping with data collection, mitigation and reclamation.
The radar station can be moved throughout the project and collect data around the clock. Scientists supplement the data by watching the sky and noting what birds the radar is picking up and logging the specifics of the species.
The radar can eventually be trained to identify the types of birds it spots. The bird data will be evaluated for seasonal patterns to take into account migration or other reasons why flight patterns might change.
The collected data will be used to help Power Co. of Wyoming decide where to place the project's turbines, said Kara Choquette, spokeswoman for the project.
Other steps mitigate bird deaths
Another way to help keep birds away from the turbines is for developers -- such as Power Co. of Wyoming -- to avoid areas that have a large eagle prey base, Wojcik said. In addition to not building in those documented areas, companies could stock other areas with more prey to draw the eagles away from the turbines to hunt, he said.
Power Co. of Wyoming also fitted guy wires with bird reflectors. Since then, no birds have been found dead near the guy wires, Wojcik said.
The company has also changed its plans by voluntarily moving proposed turbines from most of the Red Rim Grizzly Wildlife Habitat Management Area and from all sage grouse core areas, Choquette said.
The company's reclamation plan includes improving the area. Choquette highlighted one example, in which the company reseeded a lightning-scorched area with a seed mix specifically designed to enhance the area for raising sage grouse broods.
Yet even with all the mitigation efforts, eagle safety can't be guaranteed, Choquette said.
"You can't design a road that will never kill a deer," she said.
Kill questions abound
While the avian radar used at the Chokecherry and Sierra Madre project is an innovative way to collect data on high bird-count areas, there is still a lot unknown about birds and wind turbines, said Sweanor, the Fish and Wildlife Service biologist.
Questions abound: Why do some birds avoid wind turbine rotors and others don't? Is it because of the vertical display flights some birds use during breeding season? Are they so interested in showing off they forget about the surroundings in the vertical flight space?
Or do birds lose awareness of their surroundings while focused on an attack dive? Or are migrating birds or those familiar with the landscape the ones that are killed?
When an eagle is killed the death must be reported to Fish and Wildlife law enforcement officials within 24 hours of discovery, Sweanor said.
While eagles are protected under federal law, wind energy developers must consider trade-offs: How much should they be expected to do under federal law to reasonably avoid hurting birds?
Companies, feds seek balance
All unpermitted "takes," or killed eagles, are violations, Sweanor said. But the Fish and Wildlife Service has some discretion. A company that is responsible for killing the eagles but has both worked with the agency to mitigate deaths and worked to remedy future population impacts is viewed favorably by law enforcement.
Companies also have an opportunity to apply for "take" permits if there is still a likelihood of eagle deaths after all mitigation efforts are incorporated. Companies must offset expected deaths to make sure there is "no net loss to the eagle population," Sweanor said.
Each incident brings the company to wildlife agencies to see if there are better ways avoid eagle collisions with turbines. It is still unknown why eagles are especially susceptible to run-ins, he said.
Some of the worry about eagles originated in California, where there are older wind energy projects, with turbines that feature smaller, faster-spinning blades in areas with high bird populations, said Mark Tallman, vice president of renewable resources for Rocky Mountain Power.
The "extremely high mortality rates" seen at those sites aren't seen at Wyoming projects, he said. But there hasn't been enough research to know if Wyoming's lower bird death rate is because newer projects have larger blades with a bigger, slower sweep, or if there are other factors.
"The science, I hate to use the word 'lagging,'" Tallman said, "but I think because there has been a quick growth in this ... resource, the science hasn't had a chance to catch up."