September 1993 – Center staffer David Hogan filed the original petition formally requesting that the California gnatcatcher be listed under the federal Endangered Species Act.
March 30, 1993 – The U.S. Fish and Wildlife Service listed the coastal California gnatcatcher as threatened.
1996 -1998 – The Center successfully pressed for improved conservation measures for the California gnatcatcher under the San Diego Multiple Species Conservation Plan.
1998 – The Center sued the U.S. Forest Service over the agency's failure to protect the California gnatcatcher and many other species from development, off-road vehicles, cattle grazing, urban infrastructure, and other activities on four Southern California national forests. The lawsuit resulted in a landmark settlement requiring the Forest Service to prepare new land-management plans for the forests as well as interim species protection measures.
March 2003 – The Center and the San Bernardino Valley Audubon Society secured protection for 1,200 acres of high-quality habitat after challenging the legality of a proposed 2,466-unit development on California gnatcatcher and San Bernardino kangaroo rat habitat.
February 3, 2004 – The Center published a report that illustrated how the 2003 Southern California wildfire season had significant impacts on habitat for imperiled wildlife — including the coastal California gnatcatcher, which had 28 percent of its habitat burned. The report called on federal and state wildlife agencies to consider these impacts before approving new development projects. It also referenced a Center database detailing at least 1,280 pairs of gnatcatchers living where permits authorized their take in the years since the species was listed as threatened.
October 13, 2006 – A federal judge agreed with the Center and allies that a San Diego regional habitat conservation plan didn't do enough to protect endangered and threatened species — such as the coastal California gnatcatcher — that depend on wetlands in the area. The judge halted damage to wetlands in undeveloped areas within the city of San Diego.
December 6, 2006 – The Center won the rejection of a proposal by developers to eliminate a vital preserve for the California gnatcatcher and Quino checkerspot butterfly in Riverside County, California.
December 20, 2007 – The Center announced its intent to sue the Department of Energy over the designation of the Southwest National Interest Electric Transmission Corridor through the habitat of several endangered species, including the coastal California gnatcatcher. The corridor would nullify state and federal environmental laws to allow “fast-track” approval of utility and power line construction.
2007 - 2008 – The Center formally intervened in a California government proceeding to prevent destruction of California gnatcatchers and dozens of other imperiled species from San Diego Gas and Electric's proposed, 150-mile-long Sunrise Powerlink electrical transmission line.
August 11, 2011 – The Center for Biological Diversity, Friends of Coyote Hills, and the Sea and Sage Audubon Society filed a lawsuit to protect a 510-acre site in Fullerton, the proposed location of the West Coyote Hills development and the home of one of the largest populations of coastal California gnatcatchers.
December 29, 2014 – In response to a petition from the anti-wildlife group the Pacific Legal Foundation, the U.S. Fish and Wildlife Service announced that it would review the status of the coastal California gnatcatcher to determine if it still qualifies as a threatened species under the Endangered Species Act.