Solar farms provide clean energy, but new research from China suggests rapid development can come at a cost to birds and their habitat.
Building solar farms is supposed to be the easy part of fixing the climate. But panels need land, and in China most of that land was cropland or grassland with birds living on it. A new study of 2,344 Chinese counties finds that the harder a county pushed solar, the fewer kinds of birds its birdwatchers recorded.
Clean power and habitat are competing for the same ground.
Huiming Zhang and colleagues compared counties against each other. They did not follow any single solar site from before construction to after, so the study shows a pattern and not a cause. The pattern survived a long list of alternative tests.
Amateur birdwatchers logged the sightings on the China Birdwatching Record Center, where experts check each entry. Zhang works at Nanjing University of Information Science and Technology. His team matched those records to county figures on solar policy, land cover, weather, and income, month by month from 2014 through 2023.
To measure the birds, the team used a standard score. It rises when a place holds more species, and when those species are spread evenly rather than dominated by one or two.
For the policy side, they scraped official documents off provincial, city, and county government websites. Each document scored from 1 to 9, from a vague plan up to a binding regulation.
Researchers before them counted panels. This team counted the paperwork that put the panels there.
Counties with stronger solar policy had lower bird scores. Moving a county up one standard deviation on the policy scale went with a 2.10% drop in its score.
That’s a small number for one county and a large one for a country installing solar faster than anywhere else. China’s panels already covered about 1,745 square miles (4,520 square kilometers) in 2024, roughly the area of Rhode Island. By 2060 solar is projected to supply close to 45% of the country’s energy.
The authors then separated new rules from old ones. New rules coming into force tracked with a drop in bird diversity. Older rules already in force didn’t.
Whatever is happening to the birds appears to happen early in the solar expansion process.
Counties also lost species outright. The total number of species fell, while the evenness among the ones left over ticked up slightly. That’s the pattern expected when more specialized species drop out and adaptable ones divide up what remains.
The team then checked two satellite measures of plant cover, and the two disagreed. The measure that tracks how healthy and widespread plant cover is went down as solar policy tightened. The measure of how much leaf surface is stacked over a patch of ground went up.
The authors call that combination inferior greening. Land that reads as greener from orbit can be dense, uniform cover under and between the panels. It stands in for the mixed grassland or crop mosaic that used to be there.
Dense and uniform is fine if you’re a plant. It’s a problem if you’re a bird that nests in a shrub of a particular height, or one that eats the insects a varied plant community feeds.
They tested a simpler explanation and dropped it. If lights around industrial sites were pushing birds out, night-light readings should climb with solar policy. They fell instead, because large solar plants get built in empty places.
The losses landed outside China’s dry northern belt and outside its sandy and gravel deserts, and in counties never designated as poverty counties. Inside the desert zones, where birds are already adapted to bare open country, the researchers found no significant effect.
Species split the same way. China’s endemic birds, the ones concentrated in mountain forest nobody is paving for panels, came through unaffected.
Widespread species did worse, along with birds that nest in vegetation and birds that eat meat or a bit of everything. Plant-eaters, which can work with thick ground cover, showed no significant change.
Migratory and resident birds both declined. The counties with the most aggressive solar policy also overlap with major flyways, which turns a local land swap into a problem for wildlife only passing through. Those migration stopovers shape populations thousands of miles away.
Farmers in those counties harvested less, too. The authors estimate a 2.88% drop in crop yield for each one-unit rise in policy strength, an effect they report separately from the bird numbers.
Their recommendation isn’t less solar. It’s solar somewhere else. Put the big utility plants in the arid north, where clearing costs the least, and keep them off productive land in wealthier, wetter regions.
For those regions they point to rooftop arrays and to growing crops under and between the panels, which keeps some plant structure and some food production on the same land.
They also want ecological rules written into policy before the bulldozers arrive, and restoration standards that require a mix of native plants instead of the cheapest fast-growing cover.
Earth.com has reported on how wildflower borders change what lives on a solar site, and on how solar farms can be designed around wildlife from the start. Researchers are making the same case about floating panels on reservoirs.
Shanjun Li of the Stanford Doerr School of Sustainability is one of the paper’s corresponding authors, alongside co-authors in Beijing, Nanjing, Guangzhou, Maryland, and Hanoi.
Economists can tell a government roughly what a ton of carbon dioxide costs the world. No comparable figure exists for a county’s birds, so a plan that trades one for the other can only put a value on one of them.
Yuanning Liang, an economist at Peking University who wrote an accompanying commentary, called that the next job. He wrote that “credible estimates of biodiversity values are needed when sustainable development policies alter ecosystems.”
The desert-siting fix is still a recommendation rather than a tested result. This study measures what China’s counties have already built. It doesn’t measure what happens to the birds if the panels move.
The full study was published in the journal Science.
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