Still, the report from the forensics laboratory is sure to inflame long-running tensions over the impact of massive desert solar power plants on wildlife and what kind of trade-offs society is willing to make to fight climate change. The construction of Ivanpah, which was built by BrightSource Energy and now is operated by NRG Energy, faced delays when it turned out the site 45 miles south of Las Vegas is a hot spot for the imperiled desert tortoise.

The Fish and Wildlife biologists cautioned that their results are preliminary and that much more research needs to be done on avian mortality around solar power plants.

But the scientists and members of the Fish and Wildlife Service’s Office of Law Enforcement (OLE) saw first-hand those trade-offs when they visited Ivanpah, where mirrors called heliostats heat water to generate steam to drive an electricity-generating turbine. The intense light that surrounds the top of Ivanpah’s power towers attracts insects, including Monarch butterflies. Federal officials “observed large numbers of insect carcasses throughout the Ivanpah site,” according to the report. “Birds were also observed feeding on the insects. At times birds flew into the solar flux and ignited.”

Ivanpah employees called such immolations “streamers.”

When OLE staff visited Ivanpah, we observed many streamer events. It is claimed that these events represent the combustion of loose debris or insects. Although some of the events are likely that, there were instances where the amount of smoke produced by the ignition could only be explained by a large flammable biomass such as a bird. Indeed OLE observed birds entering the solar flux and igniting, consequently becoming a streamer.

The feds saw what appeared to be a bird go up in flames every two minutes, according to the report. The birds killed at Ivanpah include a peregrine falcon, a red-shouldered hawk and an ash-throated flycatcher.

The report recommends among other things that NRG shut down the power plant during peak migration times for some bird species and install video cameras to monitor birds as they fly into the solar flux.

NRG spokesman Jeff Holland took issue with some of the recommendations.

“While the report provides some initial data on bird mortality at the Ivanpah project, it also presents premature conclusions regarding the severity of impacts and proposed recommendations which are not supported by scientific literature, nor standard protocols and processes that are necessary prior to drawing scientific conclusions,” he told The Atlantic in an email. “Given that Ivanpah has only been operational for a short period of time, it is premature to determine the significance and extent of impacts to insects, birds, or bats.”

“Climate change is by far the biggest concern for all forms of wildlife on the planet and we have spent millions of dollars on projects like Ivanpah in our quest to find ways to provide clean, sustainable and renewable energy,” Holland added.