The U.S. Fish and and Wildlife Service is keeping its aim trained on the barred owl, hoping an effort to cull the species could save its close genetic relative. 

In a final plan released Wednesday, the agency is proposing to kill as many as 450,000 barred owls over 30 years, despite opposition from some animal welfare activists and Washington state’s top public lands official. 

The plan, released in a final environmental impact statement, is designed to prevent the extinction of the…