SAN DIEGO—The U.S. Fish and Wildlife Service Dec. 20 declared one of Southern California’s rarest butterflies—the Hermes copper butterfly—as a threatened species under the Endangered Species Act. The agency also designated 35,000 acres in San Diego County as a protected critical habitat. The butterfly declined from at least 57 historical populations to only 26 populations in a survey this year. “The Hermes copper butterfly is one of several threatened or endangered butterflies in our region,” said Paul Souza, regional director for the agency’s California-Great Basin Region. “We are also issuing a special rule that will provide flexibility for our partners engaged in important wildfire prevention and species research activities while providing protection for this rare butterfly.” The rule tailors protection for the species while allowing activities that do not harm recovery, including habitat restoration, species research and management of fuel breaks to reduce wildfire threats. The Center for Biological Diversity had been fighting for nearly 30 years to gain protection …