Green energy’s dirty secret

Industrial solar and wind endanger wildlife but are getting more support than ever.

Even on paper, it was a wonder: Three expansive circles of shining mirrors supplicating three glowing 500-foot-tall towers, each engineered to turn the sun’s heat into electricity in the otherwise godforsaken Mojave Desert. The Ivanpah Solar Electric Generating System offered a sparkling vision of our nature-powered future, whose every gigawatt would keep tons of coal’s heat-trapping pollutants out of the atmosphere. BrightSource Inc., a company based in Oakland, California, would design it; construction giant Bechtel would build it on 4,000 acres near the California-Nevada border. It would supply clean electricity to 140,000 homes.


In 2010, when Bechtel broke ground on Ivanpah, it held such promise that President Barack Obama worked it into a speech on the nation’s energy. “With projects like this one,” he declared, “we are staking our claim to continued leadership in the new global economy.”

As its miles of glinting glass and radiant columns rose on the landscape, tourists from China and India came on buses to marvel. It attracted a $168 million investment from high-tech giant Google; the U.S. Energy Department backed its $1.6 billion in construction loans. For many energy speculators, environmentalists and green-energy proponents, a long-held dream was finally coming true. “The wasteland of the Mojave Desert,” as one Los Angeles-based energy guru put it, was on its way to becoming the “goldmine of our future energy needs.”

BrightSource and its partners managed to weather a fracas or two over the destruction of rare plant colonies and threatened desert tortoise dens. But then, in September 2013, as engineers readied the plant to send its first sparks to the grid, burned birds started turning up on the ground within Ivanpah’s luminous expanse. Some of them — a small yellow ball of a songbird called a Wilson’s warbler, a delicate Cassin’s vireo, a peregrine falcon — looked as though they’d been struck by a death ray: Their feathers had been melted, their bodies singed.

The Ivanpah facility is a “power-tower” type of solar thermal collector; its mirrors radiate intense beams of heat known as “solar flux.” The phenomenon had killed birds before, at a small power-tower experiment that operated briefly in the 1980s near Daggett, California. Ivanpah is 40 times as big, though its dead birds came as a surprise. “You might say we didn’t look hard enough,” says Craig Turchi, an engineer with the National Renewable Energy Laboratory, who recently contributed to an analysis of Big Solar’s bird problem. “But there wasn’t any red flag.”

Before Ivanpah’s construction began, however, an ecologist named Shawn Smallwood suspected that the plant might prove even more deadly to birds than some of California’s wind farms. Smallwood had spent close to two decades trying to resolve the conflict between turbines and birds in Central California’s Altamont Pass, a particularly dangerous corridor for golden eagles drawn to the area’s grassy hills. Ornithologists since the 1970s had documented hundreds of different birds in the California desert — hawks, doves, owls and passerines — lingering around desert springs, migrating through mountain passes, or nesting in the dry lowland scrub. He worried early on that the Mojave Desert might be Big Solar’s Altamont.

He worries still. California lawmakers recently raised the renewable energy goal for the state’s utilities to 50 percent by 2030, a potential resuscitating jolt to the market for large renewable energy projects, especially since, in California, rooftop solar doesn’t count toward that quota. A new state and federal collaborative effort to locate large energy plants where they’ll do the least damage, the Desert Renewable Energy Conservation Plan, would in some cases rubber-stamp developments on crucial habitat for certain birds, like the burrowing owl. But the energy companies involved insist that their projects matter too much to the climate to be derailed by a few dead birds — when, that is, they admit that their plants kill birds at all.

To Smallwood, it’s a familiar story. Ten years ago, his efforts to count the bird kills in the Altamont Pass, and propose solutions to reduce them, nearly ended his career. The solar industry “is now doing the same thing the wind industry did,” Smallwood says. “They’ve reacted the same way.”


Doug Bell of the East Bay Regional Park District, in a 2007 photo with a golden eagle found near turbines in California’s Altamont Pass Wind Resource Area. The raptor, which had a compound wing fracture, later was euthanized.
Janice Gan/Courtesy East Bay Regional Park District

In August of 2004, the California Energy Commission published a study, Developing Methods for Reducing Bird Mortality in the Altamont Pass, the culmination of four years of research by Smallwood and biologist Carl Thelander. Smallwood and Thelander built on earlier investigations by Sue Orloff, the first biologist to notice raptor carcasses around the Altamont’s turbines. But while Orloff had searched for just six seasons, Smallwood scoured turbine strings for three and a half years. Orloff figured a few hundred birds were dying every year; Smallwood’s estimate rose into the thousands.

“This was the first time people really understood the magnitude of the issue,” Smallwood says.

Golden eagles are large, pale-brown birds with six-foot wingspans; they lock on to their prey from two miles off and dive in at racecar speeds. Like Orloff, Smallwood suspected that the birds were too focused and fast to catch the spinning blades in their fields of vision. He concluded that peregrine falcons, red-tailed hawks and American kestrels were getting whacked for similar reasons. But he didn’t just analyze the problem; he offered solutions.

Smallwood discarded a popular theory about lattice turbines providing more perching opportunities than the tubular kind; he didn’t see any evidence to support it. He also dismissed as ineffective the practice of setting out poison-laced rolled oats to control rodents. Instead, he settled on two major remedies: Move turbines out of canyons, where golden eagles do most of their foraging; and replace the many small turbines in the Altamont Pass with fewer, larger and more powerful ones, a process called “repowering.” Both would take time and money, he realized. But both were necessary if wind companies wanted to avoid violating the Migratory Bird Treaty Act, an international convention protecting a long list of wild birds, and the even more stringent Bald and Golden Eagle Protection Act. “I was always looking for ways to solve problems,” Smallwood says, “not to destroy the industry.”

Industry executives, however, saw it differently. In 2004, nearly one-third of the nation’s wind-energy capacity existed in California, where the first utility-scale wind farm went up in 1980. Most of the turbines were designed and built with subsidies that dated back to President Jimmy Carter. Companies like Florida Power and Light and Sea West had paid off their loans; they didn’t want to buy anything new.

“The equipment was running, it was already paid for, and it was a cash cow,” says Bob Thresher, a National Renewable Energy Lab research fellow who’s spent two decades working with the wind industry. “Things were going gangbusters for them, and they just didn’t want to repower.”

Thresher says that the energy companies took the bird issue seriously and formed committees to address it. But other observers disagree. Doug Bell, the wildlife program manager for the East Bay Regional Parks District, which owns one-tenth of the land in the Altamont Pass Wind Resource Area, says that the industry banded together not to address avian fatalities, but to sow doubt about their existence. “It’s like the tobacco industry forming an interest group to fund research,” he says.

A golden eagle near wind farm turbines in the Great Basin.
David Lamfrom

A golden eagle flies by a 100 KW wind turbine on Altamont Pass near Livermore, California.
Courtesy Shawn Smallwood

Smallwood didn’t expect wind proponents to embrace his work with Thelander. Yet neither did he anticipate what was to come. A year after the study’s publication, he launched a new project, researching how grazing influences bird activity in the Vasco Caves, a particularly troublesome area in the Altamont Pass. But when he went to conduct a search near a cluster of turbines owned by Wintec Energy, a team of security guards ushered him away.

“That,” Smallwood says, “was a defining moment for me.”

Over the next few years and into the next decade, industry groups and energy companies conducted a relentless campaign against Smallwood, accusing him of manufacturing data and falsifying results. “Much of the evidence of bird takes contained in the Smallwood study is altered and forged,” Fred Noble, Wintec’s CEO, wrote in a letter to the Energy Commission, adding that, “In the past 26 years I have seen only one bird killed by a windmill facility, and that was a crow killed by an open transformer.” A PowerPoint slideshow circulated among media and legislators, implying that Smallwood and Thelander counted every stray bone and feather as a turbine-felled bird. Nancy Rader, the executive director of the California Wind Energy Association, demanded that the Energy Commission throw out two formal evaluations of the study — peer reviews done according to standard scientific practice — and have industry-selected biostatisticians tackle it anew. In an unprecedented move, the Energy Commission complied.

A biologist affiliated with the California Wind Energy Association even argued that the turbine blades were too big to cut birds in half, as Smallwood claimed they did. “But we were still finding them all over the ground, cut in half,” says Smallwood. “What, did God send them to earth cut in pieces?”

The attacks reached such a pitch that a supervising deputy in the California attorney general’s office wrote an emphatic letter to two wind-company lawyers, pleading with them to stop the “sensationalized, non-scientific, personal and petty” campaign against Smallwood. “Dr. Smallwood has conducted more field research and authored and published more studies concerning the bird deaths at the Altamont Pass than any other scientist in his field,” read the letter. “The inaccurate and personal attacks … threaten the potential for a progressive discussion among the interested parties.”

Despite that defense, after 2005 the Energy Commission stopped awarding research grants to Smallwood. “I was asked to end my consultancy with the Energy Commission,” Smallwood says. (Energy Commission spokesman Michael Ward neither confirms nor denies this. “Most, if not all, of the people involved in that project are no longer with the agency,” he wrote in an email.)

Thelander, too, found himself shut out of the wind industry, for which he had conducted research since 1989. He declined to comment for this article, but in 2005, he wrote a 41-page letter to the Energy Commission, railing against the wind industry’s evident exemption from state and federal environmental laws. “Political manipulation of the regulatory process seems extraordinary in this case,” Thelander wrote, “but it appears it has in fact occurred.”

Smallwood, then in his early 40s with two young children, found the attacks devastating. “I lost work,” he says. “(The wind executives) put pressure on the commissioners, and I was blackballed by the Energy Commission for a couple of years.” A steady source of income, as well as a chance to contribute important scientific research on a developing industry, was gone.


The solar tower and shimmering panels at the Ivanpah Solar Electric Generating System in the Mojave Desert.
Ron Wolf

Almost a decade later, evidence began to emerge of industrial solar’s threat to birds.

On May 8, 2013, a worker at the Desert Sunlight photovoltaic solar plant near Joshua Tree National Park stumbled across the carcass of a chicken-sized gray-brown bird with unusually long legs — a bird that belonged near water, not on the plains of the Colorado Desert. Biologists later identified the bird as a Yuma clapper rail, one of fewer than 900 left in the wild. The bird’s death, were it proved to be associated with the 4,400-acre solar farm, would potentially constitute a violation of the Endangered Species Act, for which the plant’s primary owner and operator, Florida Power and Light under its new name, NextEra Energy Resources, could face prosecution. But the bird’s body was too decomposed to determine the cause of its death. U.S. Fish and Wildlife biologists could only speculate: A field of solar arrays viewed from above, especially in the low light of morning or evening, looks like water. The bird may have flown down expecting refreshment, and died upon collision or of exhaustion.

That theory gained traction in July of that year, when journalist Chris Clarke reported on more solar-related water bird deaths for his blog at KCET, an independent Los Angeles television station. According to reports NextEra had filed with the Energy Commission, a common loon, three western grebes and five brown pelicans were found dead or injured at Desert Sunlight and NextEra’s Genesis solar facility, 40 miles east. Genesis uses long troughs of curved mirrors to concentrate sunlight; Amedee Brickey, deputy chief of migratory birds for Fish and Wildlife’s Pacific Southwest Region, says birds might judge them as airspace, colliding headlong into glass where they expected sky.

Then, in September, workers found dead birds around Ivanpah.

Before a single mirror went up on the site, in 2010, Smallwood had been retained by a law firm to assess the plant’s threat to birds. He used data from biologist Michael McCrary’s 1986 study of birds around the Daggett plant — to this day, the only peer-reviewed research on birds and industrial solar plants. Smallwood applied updated methods of adjusting for birds that searchers might have missed and came up with an estimate of 8,000 birds killed per year.

His client, whose name is protected by a non-disclosure agreement, settled the case secretly with the developer, and the data never got out. It was just as well, Smallwood said later: “I had the rates too low.”

In spring 2014, the Center for Biological Diversity hired Smallwood to weigh in publicly on another power-tower plant that BrightSource wanted to build — and most environmentalists wanted to stop — near the Colorado River in California, the Palen Solar Energy Generating System. By that time, Ivanpah was nearing completion, and its owners were filing monthly reports with the Energy Commission that included wildlife casualties. Smallwood dug up his old estimates and compared them to the actual counts of dead birds in the reports. That June, he revealed his revised estimate at an Energy Commission hearing on the Palen proposal.

Smallwood walked the commissioners through his math: Search teams at Ivanpah had reported finding anywhere from 82 to 101 birds each month. If they followed the protocol laid out in Ivanpah’s monitoring plan, they checked only about a fifth of the site, so Smallwood estimated that perhaps five times as many birds might be dying around the plant. And because many of the birds found were tiny, vultures, foxes and other scavengers likely consumed up to three-quarters of them — another standard calculation, called “scavenger bias” in Smallwood’s field. All told, Smallwood concluded, a realistic monthly count of dead birds might surpass 2,000. “If this rate persisted year long,” Smallwood said, “then Ivanpah might be killing 28,380 birds (per year).”

The energy companies had several people ready to debate Smallwood at the hearing. One was Wally Erickson, a biologist with Western EcoSystems Technology Inc., whom BrightSource and its partner in the Palen project, Spanish developer Abengoa, hired to testify. Smallwood and Erickson were well acquainted: In 2004, Erickson submitted comments to the Energy Commission accusing Smallwood and Thelander of “data dredging”— teasing out statistical patterns that may not exist. Now, Erickson was arguing that Smallwood had overestimated scavenger bias, underestimated the search area and used only the two months of data the plant’s operators had so far released. Erickson said he had seven months of data, and used them to come up with an estimate of 1,469 birds per year — a figure that accounts only minimally for dead birds searchers missed.

A great blue heron found dead near an evaporation pond at the Genesis Solar site in the Chuckwalla Valley of Southern California.
Genesis Solar Energy Project Monthly Compliance Report #32 June 2013 in its report to the California Energy Commission

Smallwood acknowledged that his information was scant and his calculations rough. “Back-of-the-napkin-level,” he called them, a phrase that would later be used against him. But if his estimate was anywhere close to correct, he said, “then solar thermal in California’s deserts will cause far greater impacts to wildlife than did the notorious Altamont Pass Wind Resource Area.”

Gordon Pratt, a scientist who, before he retired two years ago, worked as a field entomologist for the University of California Riverside, also spoke at the Palen meeting, about the potential for solar power towers to become “ecological mega-traps.” Light from the towers, which is brighter than daylight, could attract insects, he thought, which would in turn draw in birds.

Fish and Wildlife’s forensics lab biologists had observed this phenomenon. In a preliminary report published a few months earlier, they’d described seeing “hundreds upon hundreds” of insect carcasses, including dragonflies and monarchs, falling from the sky, many of them burned. Birds feeding on the insects sometimes “flew into the solar flux and ignited,” they wrote. But when Pratt raised the issue, Richard Kaae, a professor of pest management at Cal Poly Pomona, who bills himself as an expert witness on insect behavior, spoke up to dismiss him. He insisted that diurnal insects aren’t attracted to light, because if they were, they’d fly toward the sun.

Pratt, who had testified and written up his detailed analysis for free, was astonished. He asked, “Well, then why don’t nocturnal insects fly into the moon?”

“They shouldn’t,” Kaae said, and the discussion moved on.

Two months after that hearing, the Associated Press picked up on Fish and Wildlife’s forensics lab report for a national story, headlined “Emerging Solar Plants Scorch Birds in Mid-Air.” It presented a range of estimates for birds killed at Ivanpah, not just by flux but by collisions and other hazards: a low of 1,000 per year according to the industry, and as many as 28,000 according to an “expert for the Center for Biological Diversity environmental group.” That expert, of course, was Smallwood.

Representatives from the solar industry were quick to respond. Jeff Holland, the spokesman for NRG Inc., the company that operates the Ivanpah facility, called Fish and Wildlife’s analysis “premature.” Holland’s boss, NRG CEO David Crane, declared the bird deaths a “non-issue.” BrightSource spokesman Joe Desmond, a former Energy Commission chairman, insisted in a Web post that “air in the solar field does not get hot from solar flux: it cannot absorb the flux and convert it to thermal energy.” But no credible biologist or even advocate had ever claimed otherwise: Flux needs a target to absorb heat. As BrightSource’s strategic planning director, Binyamin Koretz, explained during his own Palen testimony, “When light energy is absorbed by an object that it hits, it is converted to solar energy. Dark colors absorb more, light colors absorb less.” A dark-feathered bird, then, is an excellent absorber of flux.

A week after the AP story ran, lobbyist Frank Maisano, known for defending nuclear power, coal, oil and gas against environmental and public health laws, came to BrightSource’s defense. Quoting a 1988 hit by the hip-hop group Public Enemy, “Don’t Believe the Hype,” Maisano’s email claimed that Ivanpah’s flux had killed only 133 birds in six months. The 28,000 number was “suspect,” he said, because the scientist who came up with it admitted his calculations were “back-of-the-napkin-level, and were based on assumptions I cannot at this time verify as correct.” Maisano did not mention that Smallwood was mainly worried that his estimate was low.

Maisano was right about one thing, Smallwood admits: “There really was a napkin.”

Maisano’s pitch landed hard: Several media stories, from the Las Vegas Review-Journal to, ran stories accusing Smallwood of “truthiness” and exaggeration. Like Maisano, they said nothing of Smallwood’s plainly detailed calculations, but seized upon the scientific caution in his testimony, and used it to discredit everything he said.


Ecologist Shawn Smallwood scans the ridge lines looking for birds of prey flying among the wind turbines at Altamont Pass, California.
Robert C. Bain

Advocates of industrial renewable energy, including many environmentalists and scientists, argue that some birds and animals will have to die to reverse climate change. Benjamin Sovacool of the Vermont Law School estimates that the combined impacts of fossil-fueled electricity kill as many as 14 million birds every year. Sovacool even argues that the Altamont Pass wind farms are of net benefit to avian species, because by producing clean energy, they spare 3,217 birds that would otherwise die every year from pollution and climate change. (“Though to be fair,” he admits, “the species of birds saved would likely be different than the species killed.”)

Birds face a lot of hazards in this world: Oklahoma State University biologist Scott Loss estimates that as many as 988 million every year collide with windows on buildings big and small. The Bureau of Land Management in 2012 noted as many as 1 million die each year in oil fields. 

Then there’s the domestic cat. Everyone who worries about birds dying at renewable energy facilities gets a lecture about cats; the very mention of the word gets a laugh out of Smallwood. “Right!” he says. “Cats!” Loss has estimated that felines could kill anywhere from 1.3 billion to 4 billion birds every year; Erickson has cited similar statistics, which Maisano and other energy advocates use in their arguments.

“Sure, cats kill a lot of birds,” Smallwood laments. “So how does it help to add another mortality source?” Cats kill mice and squirrels, too, but the BLM still rejected a solar plant a few years ago for the sake of the state-threatened Mohave ground squirrel near Ridgecrest, California. Sage grouse, condors and whooping cranes have all been given special consideration in conservation matters, because they’re specific populations of birds, with specific ranges and needs.

“If birds are dying of particulate matter,” Bell says, “that’s different than wiping out a local population. That’s what we can wrap our minds around, and that’s the way environmental regulations work. We’re dealing with the infrastructure of the Migratory Bird Treaty Act, with the project-specific rules of the California Environmental Quality Act. What does it mean to kill 100 western meadowlarks in one place in a specific period of time? Do we know?” In the Altamont Pass, the golden eagle fatalities go far beyond “compensatory mortality”: The birds can’t produce enough young to replace the adults that are being killed.

The future survival of peregrine falcons and burrowing owls and golden eagles has nothing to do with cats, and everything to do with habitat. “No cat has ever killed a golden eagle,” Smallwood points out. “If it comes to that, it goes the other way.”

Neither Smallwood nor Pratt nor Bell deny the benefits of producing electricity without carbon emissions, nor do they dismiss the threat of a warming planet to birds and other animals. But they ask: If one of the reasons for reducing greenhouse gases is to protect the earth’s species, what kind of sense does it make to destroy precious wildlife habitat in the meantime? Desert ecology is especially rare, sensitive and fragile, and desert plants and animals have adapted, narrowly and specifically, to its conditions; they can’t simply move up the mountain.

The western burrowing owl, for example, a species of special concern in California, could disappear from southeastern California’s Imperial Valley if solar development proceeds according to the terms of the Desert Renewable Energy Conservation Plan. Seventy-one percent of California’s population of the compact, charismatic birds of prey reside in an area of the Imperial Valley slated for dozens of photovoltaic solar projects. The acreage set aside for solar in the plan will displace more than half of them.

“Where are they going to go?” Smallwood asks. “It’s not like they can move over.” The Yuma clapper rail has not been pushed to the brink by climate change, or soot and smog. The birds have been undone by the destruction of the freshwater marshes where they fish and nest. “That’s a problem right in front of us,” Smallwood says, “and one that we can fix right now.”


Older, smaller turbines, left, and a new, large turbine sit side-by-side at Altamont Pass California. Each large 2.3 MW turbine generates as much electricity as 23 small ones, can operate at a wider range of wind speeds, and creates fewer obstacles for birds.
Robert C. Bain

In 2009, the Obama administration, with the American Recovery and Reinvestment Act, made it easier — in fact advantageous — for wind companies to invest in new infrastructure. “It made it so that they could get an upfront cash payment for their (30 percent) tax credit,” the National Renewable Energy Lab’s Bob Thresher says. Around the same time, prices came down dramatically on the larger turbines that were thought to kill fewer birds. NextEra Energy agreed to begin repowering and relocating its Altamont wind farm turbines in 2010, following a settlement with the local Audubon chapter and other groups. In order to make sure they got it right, they hired Smallwood as their consultant.

Even the California Wind Energy Association’s Nancy Rader now celebrates repowering. One project in the Altamont Pass showed “reductions in golden eagle fatalities substantially greater than 50 percent after one year of study,” Rader wrote in a letter last year regarding the Desert Renewable Energy Conservation Plan. 

“He’s pretty outspoken and has strong opinions,” Thresher says of Smallwood, “and he’s never hesitant to express them. But we have a lot of respect for his work. We use him,” he says, “because he has a critical eye.”

Not all the energy companies in the Altamont have taken Smallwood’s advice, however. One, Altamont Wind Inc., recently won an extension from Alameda County to delay repowering until 2018. In July, Bell and other observers watched in horror as a young golden eagle fitted with a transmitter went from normal flight speed to “zero speed, zero altitude” in a string of Altamont Wind’s old-fashioned turbines. The bird had been hit before, rehabilitated, and triumphantly released into the wild just two months earlier. She crawled for 48 hours before a rancher came across her, still alive, with a fractured wing. She was later euthanized at an animal hospital.

“There’s nothing sadder,” Bell says, “than having to capture a crippled eagle.”


A MacGillivray’s warbler, one of 233 birds collected during a U.S. Fish and Wildlife study on avian mortality at Southern California solar facilities, including Ivanpah, Genesis and Desert Sunlight. The study found solar flux and impact trauma were the main causes of death.

U.S. Fish and Wildlife’s Brickey says the agency is currently talking to the developers about ways to scare the birds away from photovoltaic plants or somehow warn them that what appears to be water and sky is actually glass. But no one has come up with any solutions. “We’re still working on ways to help the birds,” she says.

NextEra, BrightSource and NRG all claim to be monitoring their plants to assess their impact on birds. NextEra began a two-year avian monitoring program this year, in collaboration with federal and state agencies, but has so far found no evidence that birds are mistaking solar panels for water sources, says spokesman Steven Stengel. “It is only a theory,” Stengel says. “It is too early to make any definitive conclusions.” A year-long survey at Ivanpah published last April found evidence of as many as 3,500 annual bird kills, which Maisano calls “low” and “a reflection,” Masiano wrote in an email, “of the extensive efforts that Ivanpah’s owners have undertaken to help reduce avian mortality.”

BrightSource and NRG have also enlisted help from an engineer at Sandia Labs, Clifford Ho, to argue that it’s physically impossible for flux to vaporize birds; the birds fly too fast for that to happen. That claim conflicts with the observations of BLM personnel and biologists, who last January watched as 130 birds combusted mid-flight during a six-hour test of a power-tower plant, SolarReserve’s Crescent Dunes facility near Tonopah, Nevada. The company says the problem arose because plant operators had focused thousands of mirrors at a single point in the sky while the plant was in standby mode, creating a shimmering halo of flux above the tower that birds couldn’t see. When the mirrors were trained instead on random spots in the sky, none of them produced enough heat to scorch a bird.

No peer-reviewed analysis has yet verified that explanation, however, and the plant is not currently operating. Neither the Ivanpah survey nor NextEra’s monitoring program have been subjected to the rigorous process of peer review. Data are scant and hard to come by: Now that the construction phase is over, California’s Energy Commission no longer requires Ivanpah’s operators to post compliance reports. Veronica Skelton, an NRG spokeswoman, refused to offer any details about mitigation efforts in an email exchange, saying only that “we are continuing to evaluate (avian deterrence devices) before we release more specific information.”

Maisano agrees that “there is not adequate data to draw conclusions about the avian impacts at solar facilities.” The U.S. Energy Department has just begun a new effort, says the National Renewable Energy Laboratory’s Craig Turchi, as of Oct. 1, “to look in more specific detail” at solar’s bird problem. “We don’t have a lot of answers just yet,” Turchi says. “At this point, we’re still trying to figure out the questions.”

Wildlife conflicts have nevertheless cast a pall over industrial renewable energy in California’s deserts, one that deepens as solar panels installed on rooftops have dropped in price and, with Tesla batteries to back them up, become more useful to the grid. Back in December 2013, the Energy Commission denied BrightSource and Abengoa’s petition to build the Palen plant, primarily out of concern for the birds. After the June hearings, the commission gave the go-ahead to a half-sized plant. (BrightSource has since pulled out; Abengoa plans to proceed alone with solar trough technology.) In June, the Los Angeles Department of Water and Power canceled a power purchase agreement with Bechtel’s Soda Mountain Solar Plant near the Mojave National Preserve, because the plant would have blocked an important migration corridor for bighorn sheep.

The best hope for resolving the conflicts, and putting large renewable energy projects in the best places for both power generation and wildlife, rests on the promise of a conscientious study of the sort Smallwood and Thelander presented 11 years ago. The only peer-reviewed research on the subject of Big Solar and birds is still the one that was done in 1986, by Michael McCrary, at a tiny plant that no longer exists. Which means that regulators have approved, and solar developers have built, an impressive 6 gigawatts of industrial solar in California — enough to supply 5 percent of the state’s electricity — without understanding, precisely and scientifically, how the technology affects the landscape.

“We want it all so we can maintain our lifestyle,” says Smallwood, who has carried a dying eagle in his arms as it called up mournfully to its soaring cohort, following overhead. “But maybe it’s our whole lives that have to change.”

Note: This article originally stated that the California Wind Energy Association “hired a biologist,” who argued that certain wind turbines were “too big to cut birds in half.” In fact, the biologist, who has been affiliated with CalWEA, made that claim separately. We regret the confusion.