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A new study by University of Hawaii researchers looks at the role solar panels play in bird deaths and offers suggestions to mitigate the deaths.

The by Jay Penniman and David Duffy of the at UH Manoa offers best management practices to better protect the islands’ endangered avians.

“We are the leading endangered species home for the world, unfortunately,” said Penniman, manager of the . “And a number of the birds we’re talking about are endangered.”

The widespread development of solar arrays in Hawaii is “likely to result in the death of endangered birds (given the overwhelming evidence for this on the mainland),” the report says.

Nevertheless to support solar energy production, the researchers say mitigation efforts should go hand in hand with development plans.

According to , “Scientists estimate between 37,800 and 138,600 birds die in the U.S. from all forms of solar energy production annually, compared with the 14.5 million avian deaths attributed to fossil fuel power plants.” The oil from the 1989 Exxon Valdez spill alone killed about 250,000 seabirds, according to the U.S. Geological Survey.

In Hawaii, the endangered species most likely to interact with solar facilities and the ones most at risk of being harmed are three seabirds — ‘aʻo (Newell’s shearwater), ʻuaʻu (Hawaiian petrel) and the ʻakeʻake (band-rumped storm petrel) — and five waterbirds, including the ʻalae ula (Hawaiian common gallinule), ʻalea keʻokeʻo (Hawaiian coot), koloa maoli (Hawaiian duck), ae‘o (Hawaiian stilt) and the nene (Hawaiian goose), according to the report. Another 32 species of shorebirds and waterbirds, and the pueo (Hawaiian short-eared owl), are also at risk, the report says.

Seabirds and waterbirds can mistake solar panels for bodies of water because of what is known as the “lake effect.” Solar panels reflect polarized light as water does, and birds used to a watery landing can be in for a hard surprise.

“The bird thinks it’s landing on water,” Penniman said.

Solar panels that reflect the sky can also trick birds who mistake them for a “safe passage” and collide with them.

A collision can kill birds or break their legs or wings, leading to a slow death, possibly in the jaws of a predator. While “such collisions often do not result in direct mortality,” the report says, birds sometimes cannot take off afterward because “they are adapted to take off from water, not dry land.”

Evidence of solar panels killing birds in Hawaii, however, has not been overwhelming.

“Little data is available on the potential impact to endangered seabirds,” the report says.

So far, one ‘alae keʻokeʻo, or Hawaiian coot, was found dead at a solar field on Kauai. Penniman said he thinks impact was the cause of death in that case.

Kauai hosts 90% of the ‘a‘o and one-third of the ʻua‘u in the world today, the report says.

Because of the precarious nature of Hawaii’s bird species and the unquantified threat utility-scale solar developments might pose to them, Penniman urged observing the “precautionary principle” for further solar development.

“If we don’t take their needs into consideration, we’re going to endanger them,” he said. “There’s a lot yet to be learned.”

To prevent birds from hurling themselves into solar panels, the report suggests year-round monitoring of solar fields for avian deaths and injuries and siting the fields away from flight paths, seabird colonies, wetlands and areas where sensitive species live.

One way to “reduce the attractiveness of solar panels to birds,” the report says, is to use panels that tilt upright overnight — when seabirds and waterbirds log most of their miles — to look less like water.

The report cites research on reducing the attractiveness of solar panels to insects by adding thin white borders and grids to solar panels, but whether that would deter birds is unclear. In addition to plastic decoys of predator birds, a “particularly cost-effective solution” would be playing the sounds of predators or the distress calls of prey species.

Other mitigation efforts include controlling predators like rats, cats, owls, dogs, pigs and mongooses, and enhancing the visibility of wires that birds might hit, using reflectors or other markers.

The cost of mitigation efforts would depend on their extent. Penniman estimates it would likely be marginal, though “it’s not something we have quantified.”

Civil Beat’s coverage of Maui County is supported in part by a grant from the Nuestro Futuro Foundation.

Read the full report below.