Partial development of the San Bruno Mountain habitat of the rare Mission Blue Butterfly is not a threat to the endangered insect, a federal appeals court in San Francisco ruled. The court upheld a lower court ruling that the U.S. Wildlife Service had already taken reasonable precautions to preserve the butterfly during the building of a subdivision. The earlier ruling had been challenged by the Friends of Endangered Species, which sued three cities, San Mateo County, three developers, landowners and the U.S. Fish and Wildlife Service in an attempt to prevent the development. The group’s lawyer, Michael Freund, said he was saddened by the appeal court ruling. “It’s like a death,” he said.