SAN FRANCISCO — Federal wildlife officials announced a proposal to classify one of two dwindling California spotted owl populations as endangered after a lawsuit by conservation groups required the government to reassess a decision not to protect the brown and white birds. The U.S. Fish and Wildlife Service proposed that California spotted owls that have their habitats in coastal and Southern California be protected under the Endangered Species Act. That population “does not have a strong ability to withstand normal variations in environmental conditions,” which led the agency to propose listing it as endangered, wildlife officials said. The other California spotted owl population, which lives in Sierra Nevada forests in California and western Nevada, would be classified as threatened, the agency said. The habitat of the medium-sized brown owl… is under serious threat from current logging practices and climate change, including increased drought, disease and more extreme wildfires.