This article was originally published by Undark Magazine.

“This is one of the least smelly carcasses,” says Todd Katzner, peering over his lab manager’s shoulder as she slices a bit of flesh from a dead pigeon lying on a steel lab table. Many of the specimens that arrive at this facility in Boise, Idaho, are long dead, and the bodies smell, he says, like “nothing that you can easily describe, other than yuck.”

A wildlife biologist with the U.S. Geological Survey, a government agency dedicated to environmental science, Katzner watches as his lab manager roots around for the pigeon’s liver and then places a glossy maroon piece of it in a small plastic bag labeled with a biohazard symbol. The pigeon is a demonstration specimen, but samples, including flesh and liver, are ordinarily frozen, cataloged, and stored in freezers. The feathers get tucked in paper envelopes and organized in filing boxes; the rest of the carcass is discarded. When needed for research, the stored samples can be processed and sent to other labs that test for toxicants or conduct genetic analysis.

Most of the bird carcasses that arrive at the Boise lab have been shipped from renewable-energy facilities, where hundreds of thousands of winged creatures die each year in collisions with turbine blades and other equipment. Clean-energy projects are essential for confronting climate change, Mark Davis, a conservation biologist at the University of Illinois at Urbana-Champaign, says. But he also emphasizes the importance of mitigating their effects on wildlife. “I’m supportive of renewable-energy developments. I’m also supportive of doing our best to conserve biodiversity,” Davis says. “And I think the two things can very much coexist.”

To this end, Katzner, Davis, and other biologists are working with the renewable-energy industry to create a nationwide repository of dead birds and bats killed at wind and solar facilities. The bodies hold clues about how the animals lived and died, and could help scientists and project operators understand how to reduce the environmental impact of clean-energy installations, Davis says.

The repository needs sustained funding and support from industry partners to supply the specimens. But the collection’s wider potential is huge, Davis adds. He, Katzner, and the other biologists hope the carcasses will offer an array of wildlife researchers access to the animal samples they need for their work, and perhaps even provide insights into future scientific questions that researchers haven’t thought yet to ask.

In 1980, California laid the groundwork for one of the world’s first large-scale wind projects when it designated more than 30,000 acres east of San Francisco for wind development, on a stretch of land called the Altamont Pass. Within two decades, companies had installed thousands of wind turbines there. But there was a downside: Although the sea breeze made Altamont ideal for wind energy, the area was also used by nesting birds. Research suggested they were colliding with the turbines’ rotating blades, leading to hundreds of deaths among red-tailed hawks, kestrels, and golden eagles.

“It’s a great place for a wind farm, but it’s also a really bad place for a wind farm,” says Albert Lopez, the planning director for Alameda County, where many of the projects are located.

A 2004 report prepared for the state estimated the number of deaths and offered recommendations that the authors said could add up to mortality reductions of anywhere from 20 to 50 percent. The most effective solution, the authors argued, involved replacing Altamont’s many small turbines with fewer, larger turbines. But, the authors wrote, many measures to reduce deaths would be experimental, “due to the degree of uncertainty in their likely effectiveness.” More than a decade of research, tensions, and litigation followed, focused on how to reduce fatalities while still producing clean electricity to help California meet its more and more ambitious climate goals.

While all this was happening, Katzner was earning his Ph.D. by studying eagles and other birds—and beginning to amass a feather collection halfway around the world. In Kazakhstan, where he has returned nearly every summer since 1997 to conduct field research, Katzner noticed piles of feathers underneath the birds’ nests. Carrying information about a bird’s age, sex, diet, and more, they were too valuable a resource to just leave behind, he thought, so he collected them. It was the start of what he describes as a compulsion to store and archive potentially useful scientific material.

Katzner went on to co-publish a paper in 2007 in which the researchers conducted a genetic analysis of naturally shed feathers, a technique that could allow scientists to match feather samples with the correct bird species when visual identifications are difficult. He later towed deer carcasses across the East Coast to lure and trap golden eagles in order to track their migration patterns. Today, part of his research involves testing carcasses for lead and other chemicals to understand whether birds are coming in contact with toxicants.

For the past decade, Katzner has also researched how birds interact with energy installations such as wind and solar projects. During this time, studies have estimated that hundreds of thousands of birds die each year at such facilities in the United States. That’s still a small fraction of the millions of birds that at least one paper estimated are killed annually because of habitat destruction, downstream climate change, and other impacts of fossil-fuel and nuclear-power plants. But renewable energy is growing rapidly, and researchers are trying to determine how that continued growth might affect wildlife.

[Read: The quiet disappearance of birds in North America]

Bats seem attracted to wind turbines and are occasionally struck by the blades while attempting to roost in the towers. Birds sometimes swoop down and crash into photovoltaic solar panels—possibly thinking the glass is water that is safe for landing. A separate, less common solar technology that uses mirrors to concentrate the sun’s rays into heat energy is known to singe birds that fly too close—a factor that has drawn opposition to such facilities from bird activists. But scientists still don’t fully understand these many interactions or their impacts on bird and bat populations, which makes it harder to prevent them.

In 2015, by then on staff at the USGS, Katzner and a team of other scientists secured $1 million from the California Energy Commission to study the impacts of renewable energy on wildlife—using hundreds of carcasses from the Altamont Pass. NextEra Energy, one of the largest project owners there, chipped in a donation of approximately 1,200 carcasses collected from their facilities in Altamont.

The team analyzed 411 birds collected over a decade at Altamont and another 515 picked up during a four-year period at California solar projects. They found that many of the birds originated from across the U.S., suggesting that renewable facilities could affect faraway bird populations during their migrations. In early 2021, Katzner and a team of other scientists published a paper examining specimens collected at wind facilities in Southern California. Their results suggested that replacing old turbines with fewer, newer models did not necessarily reduce wildlife mortality. Where a project is sited and the amount of energy it produces are likely stronger determinants of fatality rates, the authors said.

In Altamont, scientists are still working to understand impacts for birds and bats, and a technical committee has been created to oversee the work. Ongoing efforts to replace old turbines with newer ones are meant to reduce the number of birds killed there, but whether it’s working remains an open question, Lopez says. The installation of fewer turbines that produce more energy per unit than earlier models was expected to provide fewer collision points for birds and more space for habitat. And when new turbines are put in, scientists can recommend spots within a project site where birds may be less likely to run into them. But other variables influence mortality aside from turbine size and spacing, according to the 2021 paper written by Katzner and other scientists, such as season, weather, and bird behavior in the area.

On a small road in Altamont, a white sign marks an entrance to NextEra’s Golden Hills wind project, where the company recently replaced decades-old turbines with new, larger models. Not far away, another wind-project sits dormant—a relic from another time. Its old turbines stand motionless, stocky, and gray next to their graceful, modern successors on the horizon. The hills are quiet except for the static buzz of power cables.

Some conservationists are still concerned about the area. In 2021, the National Audubon Society, which says it strongly supports renewable energy, sued over the approval of a new wind project in Altamont, asserting that the county didn’t do enough environmental review or mitigation for bird fatalities.

Katzner attributes his work in California with the beginnings of the repository, which he’s dubbed the Renewables-Wildlife Solutions Initiative. Amy Fesnock, a Bureau of Land Management wildlife biologist who collaborates with Katzner, simply calls it the “dead-body file.”

In Idaho, Katzner has already amassed more than 80,000 samples—many drawn from the feather collection he’s kept for decades, and thousands more recently shipped in by renewable-energy companies and their partners. Ultimately, Katzner would like to see a group of repository locations, all connected by a database. This would allow other scientists to access the bird and bat samples and use them in a variety of ways, extracting their DNA, for example, or running toxicology tests.

“Every time we get an animal carcass, it has value to research,” Katzner says. “If I think about it from a scientific perspective, if you leave that carcass out there in the field, you’re wasting data.”

Those data are important to people like Amanda Hale, a biologist who helped build the repository while at Texas Christian University. She is now a senior research biologist at Western EcoSystems Technology, a consulting company that, along with providing other services, surveys for dead wildlife at renewable-energy sites. Part of her new role involves liaising with clean-energy companies and the government agencies that regulate them, ensuring decision makers have the most current science to inform projects. Better data could assist clients in putting together more accurate conservation plans and help agencies know what to look for, she says, simplifying regulation.

“Once we can understand patterns of mortality, I think you can be better in designing and implementing mitigation strategies,” Hale says.

The initiative is not without its skeptics, though. John Anderson, the executive director of the Energy and Wildlife Action Coalition, a clean-energy membership group, sees merit in the effort but worries that the program could be “used to characterize renewable-energy impacts in a very unfavorable light” without recognizing its benefits. The wind industry has long been sensitive to suggestions that it’s killing birds.

Several renewable-energy companies that Undark contacted for this story did not respond to inquiries about wildlife monitoring at their sites or stopped responding to interview requests. Other industry groups, including the American Clean Power Association and the Renewable Energy Wildlife Institute, declined interview requests. But many companies appear to be participating—in Idaho, Katzner has received birds from 42 states.

William Voelker, a member of the Comanche Nation who has led a bird-and-feather repository called Sia for decades, says he’s frustrated at the lack of consideration for tribes from these types of U.S. government initiatives. Indigenous people, he says, have first right to “species of Indigenous concern.” His repository catalogs and sends bird carcasses and feathers to Indigenous people for ceremonial and religious purposes, and Voelker also cares for eagles.

“At this point we just don’t have any voice in the ring, and it’s unfortunate,” Voelker says.

Katzner, for his part, says he wants the project to be collaborative. The Renewables-Wildlife Solutions Initiative has sent some samples to a repository in Arizona that provides feathers for religious and ceremonial purposes, he says, and the RWSI archive could ship out other materials that it does not archive, but it has not yet contacted other locations to do so.

“It’s a shame if those parts of birds are not being used,” he says. “I’d like to see them get used for science or cultural purposes.”

Many U.S. wind farms already monitor and collect downed wildlife. At a California wind facility a little over an hour north of Altamont, the Sacramento Municipal Utility District tries to clear out its freezers at least once a year—before the bodies start to smell, Ammon Rice, a supervisor in the government-owned utility’s environmental-services department, says. Many of the specimens that companies accumulate are kept until they’re thrown out. Until recently, samples had been available to government and academic researchers on only a piecemeal basis.

There are many reasons why a clean-energy company might employ people to pick up dead animals at its facility: Some areas require companies to survey sites during certain stages of their development and keep track of how many birds and bats are found dead. Removing the carcasses can also deter scavengers, such as coyotes, foxes, and vultures. And the federal government has set voluntary conservation guidelines for wind projects; for some companies, complying with the recommendations is part of maintaining good political relationships.

Most of the time, human searchers canvas a project, walking transects under turbines or through solar fields. It’s “enormously labor-intensive,” says Trevor Peterson, a senior biologist at Stantec, one of the consulting firms often hired to conduct those surveys. On some sites, trained dogs sniff out the dead bodies.

[Read: Are wind turbines a danger to wildlife? Ask dogs.]

For years, conservation biologists have wanted to find a use for the creatures languishing in freezers at clean-energy sites around the country. To get a nationwide project off the ground, Katzner started working with two other researchers: Davis, the conservation biologist at University of Illinois, and Amanda Hale, then a biology professor at TCU. They were part of a small community of people “who pick up dead stuff,” Katzner says. The three started meeting, joined by scientists at the Bureau of Land Management and the U.S. Fish and Wildlife Service, who helped connect the initiative with additional industry partners willing to send carcasses.

Building on Katzner’s existing samples, the repository has grown from an idea to a small program. In the past two years, Katzner said in an email, it received about $650,000 from the Bureau of Land Management. It also earned a mention in the agency’s recent report to Congress about its progress toward renewable-energy growth.

Davis had already been accepting samples from wind facilities when he started working on the repository. Typically the bodies are mailed to his laboratory, but he prefers to organize hand-to-hand deliveries when possible, after one ill-fated incident in which a colleague received a shipped box of “bat soup.” To receive deliveries in person, Davis often winds up loitering in the university parking lot, waiting for the other party to arrive so they can offload the cargo.

“It sounds a lot like an illicit drug deal,” Davis says. “It looks a lot like an illicit drug deal—I assure you it is not.”

Recently, Ricky Gieser, a field technician who works with Davis, drove a few hours from Illinois to central Indiana to meet an Ohio wildlife official in the parking lot of a Cracker Barrel. Davis arranged for Undark to witness the exchange through Zoom. With latex-gloved hands, Gieser transferred bags of more than 300 frozen birds and bats—lifting them from state-owned coolers and then gingerly placing them into coolers owned by his university. The entire transaction was over in less than 15 minutes, but coordinating it took weeks.

Davis studies bats and other “organisms that people don’t like,” with a focus on genetics. He grew up in Iowa chasing spiders and snakes and now stores a jar of pickled rattlesnakes—a souvenir from his doctoral research—on a shelf behind his desk. Protecting these creatures, he says, is of extreme importance. Bats provide significant economic benefit, eating up bugs that harm crops. And their populations are declining at an alarming rate: A disease called “white-nose syndrome” has wiped out more than 90 percent of the population of three North American bat species in the last decade. In late November of 2022, the U.S. Fish and Wildlife Service listed Davis’s favorite species, the northern long-eared bat, as endangered.

For certain species, deaths at wind facilities are another stressor on populations. Scientists expect climate change to make the situation worse for bats and overall biodiversity. “Because of this confluence of factors, it’s just really tough for bats right now,” Davis says. “We need to work a lot harder than we are to make life better for them.”

Like other wildlife researchers, Davis has sometimes struggled to get his hands on the specimens he needs to track species and understand their behaviors. Many spend time in the field, but that’s costly. Depending on the target species, acquiring enough animals can take years, Davis says. He used museum collections for his doctoral dissertation, and still views them as an “untapped font of research potential.” But many museums focus on keeping samples intact for preservation and future research, so they may not work for every project.

That leaves salvage. Frozen bird and bat carcasses are “invaluable” to scientists, said Fesnock, the Bureau of Land Management wildlife biologist. So far, samples collected as part of the Renewables-Wildlife Solutions Initiative have led to about 10 scientific papers, according to Katzner. Davis says the collection could reduce research costs for some scientists by making a large number of samples available, particularly for species that are hard to collect. Catching migratory bats that fly high in the air with nets is difficult for scientists, which makes it challenging to estimate population levels. Bat biologists say there’s much we still don’t know about their behaviors, range, and number.

As scientists work to compile better data, a few companies are experimenting with mechanization as a possible way to reduce fatalities at their facilities. At a wind farm in Wyoming, the utility Duke Energy has installed a rotating camera that resembles R2-D2 on stilts. The technology, called IdentiFlight, is designed to use artificial intelligence to identify birds and shut turbines down in seconds to avoid collisions.

Prior to IdentiFlight, technicians used to set up lawn chairs amid the 17,000-acre site and look skyward, sometimes eight hours a day, to track eagles. It was an inefficient system prone to human error, says Tim Hayes, who recently retired as the utility’s environmental-development director. IdentiFlight has reduced eagle fatalities there by 80 percent, he adds. “It can see 360 degrees, where humans can’t, and it never gets tired, never blinks, and never has to go to the bathroom.”

Biologists say there are still unknowns around the efficacy of these types of technologies, in part because of incomplete data on the population size and spread of winged wildlife.

Katzner and his colleagues want the repository to help change this, but first they will need long-term funding to help recruit more partners and staff. Davis estimates he needs between $1 million and $2 million to build a sustainable repository at his university alone. Ideally, the USGS portion of the project in Boise would have its own building. For now, Katzner stores feathers in a space that doubles as a USGS conference room. Next door, in a room punctuated with a dull hum, the walls are lined with freezers. Some carry samples already cataloged. Others hold black trash bags filled with bird and bat bodies just waiting to be processed.

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