Federal wildlife officials plan to dispatch armed bird specialists into forests of the Pacific Northwest starting this fall to shoot one species of owl to protect another that is threatened with extinction.

The U.S. Fish and Wildlife Service on Tuesday released a final environmental review of an experiment to see if killing barred owls will allow northern spotted owls to reclaim territory they’ve been driven out of over the past half-century.

The agency has been evaluating the idea since 2009, gathering public comment and consulting ethicists, focus groups and scientific studies. It will issue a final decision on the plan in a month.

“If we don’t manage barred owls, the probability of recovering the spotted owl goes down significantly,” said Paul Henson, Oregon state supervisor for Fish and Wildlife.

The agency’s preferred course of action calls for killing 3,603 barred owls in four study areas in Oregon, Washington and Northern California in the next four years.

The plan is expected to cost about $3 million and requires a special permit under the Migratory Bird Treaty Act, which prohibits killing nongame birds.

Neither the timber industry nor the Audubon Society was pleased with it.

“Shooting a few isolated areas of barred owl isn’t going to help us as forest managers, nor is it going to help the forest be protected from wildfires, and catastrophic wildfire is one of the big impediments to spotted owl recovery,” said Tom Partin, president of the American Forest Resource Council, a timber industry group.

Bob Sallinger, conservation director for the Audubon Society of Portland, said saving the spotted owl is of paramount importance, but the focus must remain on protecting habitat.

“To move forward with killing barred owls without addressing the fundamental cause of spotted owl declines, from our perspective, is not acceptable,” he said.

Henson said the Northwest Forest Plan, which cut logging by 90 percent on national forests in the 1990s, has done a good job of providing habitat for the spotted owl. But the owls’ numbers have continued to slide.

Henson said unless barred owls are brought under control, the spotted owl in coming decades might disappear from Washington’s northern Cascade Range and Oregon’s Coast Range, where the barred owl incursion has been greatest.

The northern spotted owl is an icon of bitter disputes between the timber industry and environmentalists over the use of Northwest forests. Because of its dwindling numbers, the little bird was listed as a threatened species in 1990, which resulted in logging cutbacks and lawsuits.

Barred owls are bigger, more aggressive and less picky about food. They started working their way across the Great Plains in the early 1900s, and by 1959 were in British Columbia. Barred owls now cover the spotted owl’s range, in some places outnumbering them as much as 5-to-1.