The California condor’s slow 20-year climb back from the brink of extinction has long been a fragile not-quite-success story in the conservation world. So when the news came on Friday that developers of a wind-energy project near the Mojave Desert would not face criminal charges if the blades killed a single condor, environmental groups expressed grave concern.

“This blindsided folks,” Kelly Fuller of the American Bird Conservancy said in an interview, adding that the public was not aware that allowing unpenalized condor deaths was being considered there.

In a news release, she wrote that “allowing the legal killing of one of the most imperiled birds in the United States threatens endangered species conservation efforts across the country.”

It has been 46 years since the condor — a bald, black carrion-eater that can fly nearly three miles high on wings that span up to 10 feet — was declared endangered. In that time, the Interior Department’s Fish and Wildlife Service has almost never waived criminal penalties for the “taking,” or killing, of a condor.