The threat large-scale solar developments pose to tortoise in the desert Southwest has been well established, but what about the technology’s effect on birds?
The question has been asked before — David Danelski of the Riverside Press Enterprise reported on it in Feburary of 2012 — but it emerged most dramatically last winter during the California Energy Commission hearings on a five square mile-sized concentrating solar facility that Oakland-based BrightSource, Inc. had proposed to build near Pahrump, Nev. Concentrating solar technology uses mirrors, or “heliostats,” to focus the sun’s energy on a "power tower" where fluid flashes to steam and spins a turbine. Those mirrors create a field of solar flux up to 750 degrees Fahrenheit; biologists from the U.S. Fish and Wildlife Service, among others, worried that “elevated levels of solar flux generated by the focused energy from the heliostats may burn and damage exposed skin and feathers” of birds flying through those fields.
Now, however, the relationship between large-scale desert solar and the avian community may be getting even worse. In July, Chris Clarke, a journalist who lives in the Mojave town of Joshua Tree, Calif., blogged about another potential impact of large-scale solar on birds, involving an entirely different type of solar technology: Large fields of photovoltaic solar panels, which turn solar radiation into electricity. Several species of water birds — great blue herons, bufflehead ducks, grebes and even a common loon — were recently found dead near First Solar's Desert Sunlight photovoltaic field near Joshua Tree National Park. And those kinds of birds aren't typically seen in such places — dead or alive.
What's happening? Clarke suspects that from above, a shiny field of glass might look a refreshing respite to water birds migrating along the Pacific Flyway, the ancestral migratory route that extends from South America to the Arctic. When they land and find they're wrong, they're too overheated or exhausted to take off again. "With millions of years of evolutionary experience telling birds that broad expanses of glare and reflectivity on the ground mean 'water,'" he writes, "it's not hard to figure out why water birds might veer miles out of their way to head for solar facilities."
Dead water birds have also been found not far southeast of Desert Sunlight, at NextEra Solar's Genesis plant, another concentrating solar facility that uses parabolic troughs of mirrors to heat fluid. If Clarke's theory proves true, it might be that arrays of mirrors might have the same water-mimicking effect in certain regions. With 91 percent of California's wetlands having disappeared in the past century, this stretch of desert is a particularly challenging one for migrating birds, with not much to offer between the Salton Sea to the south and wetlands farther north.
So far, though, it's all speculation. No one expected to find these birds in the desert, and no one knows what to do now that they're turning up dead. "We really need more robust monitoring information," says Jane Hendron, a spokeswoman for the U.S. Fish and Wildlife Service in Palm Springs, Calif. "We don’t know if the deaths are occurring during specific times of day or night, when the moon is in a particular phase or what other complicating factors exist." For that matter, it's not clear that the birds deaths aren't normal." Absent these solar farms, how many birds would get overcome with the heat, weakness or fatigue in that part of the desert?" Hendron asks.
It's a reasonable question, says Garry George, the director of renewable energy projects for California Audubon. Birds' bodies decompose quickly, and the desert is full of scavengers. "A coyote would be happy to come across a great blue heron dying on the desert floor," George says. "You'd never even know it was there."
The bird puzzle poses the same problem that comes up almost every time an energy company develops on unoccupied desert land: The southwestern deserts just haven't been studied enough to predict what the impact of development might be. That's been true with the elusive desert tortoise, and now it's proved true with birds. "Movement of birds in the desert isn't something we know a lot about," George says. "We know where the stopovers are, but we don't know how they get there." It's one thing to map landscape corridors for migrating bighorn sheep, quite another to map migratory routes in the sky. "There's a big data gap," George says.
Hendron says that in the future, bird monitoring will be built into applications for solar development, just as it is with wind. George is hoping that opens up new opportunities for research, such as more comprehensive mapping of migratory pathways with radar.
"It's something we've been advocating for years," says George, who's been contributing ideas to the Desert Renewable Energy Conservation Plan (DRECP), a massive collaborative effort to assign appropriate sites for renewable energy, due out in draft form later this year. In the meantime, he recommends following the sound guidance given by the DRECP's independent science advisor in 2010.
"Don't permit anything you might regret," George paraphrases. "In the desert, the impacts are permanent."
Judith Lewis Mernit is a contributing editor for High Country News. Image courtesy of Flickr user e pants.