Under pressure from the Bush administration, a federal judge yesterday revoked the protected status of several hundred thousand acres of Southern California land considered essential for the survival of two imperiled species. U.S. District Judge Stephen Wilson called on the U.S. Fish and Wildlife Service to re-assess the economic effects of protecting the land on behalf of the tiny California gnatcatcher and the San Diego fairy shrimp. The move is part of a sweeping reevaluation of millions of acres of land that have been set aside as “critical habitat” for at-risk species. Real estate developers, ranchers, and farmers have lobbied for an easing of restrictions on use of critical habitat areas, and in many cases have filed lawsuits challenging the government’s financial assessments of protection measures. Conservationists fear the ruling presages dark times for the Endangered Species Act.