Before a plant or animal species can receive the full range of protective measures under the Endangered Species Act (ESA), it must first be added to the Federal List of Endangered and Threatened Wildlife and Plants (Federal Lists). These Federal Lists contain the names of all species of mammals, birds, reptiles, amphibians, fishes, insects, plants, and other creatures that have been determined by the U.S. Fish and Wildlife Service (Service) and the National Marine Fisheries Service to be in the greatest need of Federal protection.
You may locate the Federal Lists within the Code of Federal Regulations.
Adding species to the Federal Lists may occur through either the petition process or through the candidate assessment process. The ESA provides that any interested person or organization may petition the Service to add, remove, or change the status of a species. Through the candidate assessment process, our Service biologists identify species they believe meet the definition of threatened or endangered. We refer to the identified species as listing candidates.
The steps involved in the listing process follow a complex and strict legal process known as a rulemaking (or regulatory) procedure. Both the petition and candidate assessment processes may result in a species being proposed for addition to the Federal Lists.
For more information about how a species becomes listed under the ESA, please visit our national website.
• Frequently Asked Questions
• Candidate Species pdf (229 KB)
When a species is proposed for listing as endangered or threatened under the ESA, we must consider whether there are areas of habitat we believe are essential to the species’ conservation. Therefore, we must also propose critical habitat.
Critical habitat is a specific geographic area(s) containing physical and biological features essential for the conservation of a threatened or endangered species and which may require special management considerations or protection. These areas may include lands occupied or not currently occupied by the species.
Critical habitat shall not cover the entire range of a species, unless the Secretary determines it is necessary. Please see our national website for more information about Critical habitat.
To view critical habitat boundaries in a GIS format for CFWO threatened and endangered species, please go to GIS DATA.
For additional information regarding final critical habitat boundaries across the U.S., please go to the Service's Interactive Critical Habitat Portal.