Plant and animal species may be designated as threatened or endangered species under the California Endangered Species Act (CESA) after a formal listing process by the 
California Fish and Game Commission. The criteria and process for listing a species as candidate, threatened or endangered are presented in Fish and Game Code Sections 2050, et seq. and Section 670.1, Title 14, California Code of Regulations.
After the Commission receives a CESA listing petition with the required information, CDFW is responsible for preparing a petition evaluation report that includes a recommendation on whether the petition contains sufficient scientific information to indicate that the petitioned action may be warranted. After receiving CDFW’s petition evaluation report, the Commission must decide at a public meeting whether to accept the petition for consideration. If the petition is accepted the species becomes a candidate species, and CDFW begins preparing a peer-reviewed status report on the species that is based on the best scientific information available to CDFW. As a candidate for listing, the species is temporarily afforded the same protections as a state-listed endangered or threatened species. After CDFW’s status report is complete, the Commission must decide at a public meeting whether the petitioned action is warranted. If the Commission finds that the petitioned action is not warranted, the process ends, and the species will be removed from the list of candidate species. If the Commission finds that the petitioned action is warranted, the species will be added to the list of threatened or endangered species.
For more information on the CESA listing process, see the Commission’s web page on Petitions to List Species Under the California Endangered Species Act.