The Congress enacted the Endangered Species Act in 1973 to conserve threatened or endangered plant and animal species. The act requires the Service to base its determination of whether a species is endangered or threatened solely on the basis of the best available scientific and commercial data. Available data includes biological or trade data obtained from scientific or commercial publications, administrative reports, maps or other graphic materials, or experts on the subject. Using the best available data, the act requires the Service to determine whether a species should be listed as threatened or endangered by analyzing its status based on the following five factors: present or threatened destruction, modification, or curtailment of a species habitat or range; overuse for commercial, recreational, scientific, or educational inadequacy of existing regulatory mechanisms; or other natural or manmade factors affecting a species’ continued existence. As of June 2003, the Service had listed 1,263 species in the United States as threatened or endangered. This total included 517 animal species and 746 plant species. The number of species listed per year has varied considerably, as shown in figure 1. There are also 558 foreign species listed as threatened or endangered. As of June 2003, the Service was in the process of listing 36 more species and had identified 251 species as candidates for listing. The act also requires the Service to designate critical habitat for listed species. Critical habitat is a specific geographic area that is essential for the conservation of a threatened or endangered species and that may require special management and protection. As of June 2003, 417 domestic species had critical habitat designated. The number of critical habitat designations per year has varied considerably, as shown in figure 2. The Endangered Species Act has provisions to protect and recover species once they are listed. The act prohibits the “taking” of listed animal species by any party—federal or nonfederal. “Taking” or “take” means to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect a listed species. Also, federal agencies must ensure that their activities, or any activities they fund, permit, or license, do not jeopardize the continued existence of a listed species or result in the destruction or adverse modification of its critical habitat. The act establishes a process for federal agencies to consult with the Service about their activities that may affect listed species. In addition, the act requires that the Service develop a recovery plan to reverse the decline of each listed species and ensure its long-term survival. A recovery plan may include a variety of methods and procedures to recover listed species, such as protective measures to prevent extinction or further decline, habitat acquisition and restoration, and other on-the-ground activities for managing and monitoring endangered and threatened species. To date, seven domestic species have been delisted due to recovery. (App. II provides additional information on the process used by the Service to protect listed species.) The Endangered Species Act requires the Service to use the best available scientific data when deciding to list species or designate critical habitat. The “best available” standard does not obligate the Service to conduct studies to obtain missing data, but it prohibits the Service from ignoring available data. The Service goes through an extensive series of procedural steps that involves public participation and review by outside experts to help ensure that it collects relevant data and uses it appropriately. Although the process alone is not sufficient to ensure the accuracy of the Service’s listing and critical habitat decisions, it generally ensures that the Service is using and considering the “best available” data. The Service follows a rigorous process in listing a species as endangered or threatened, designating critical habitat, or removing a species from the endangered and threatened list. The Service’s process includes following a rulemaking procedure, established by the Endangered Species Act, supported by additional procedures under Service regulations and guidance. The complete text of the proposed and final rules and related information (including a summary of data on which the proposal is based and a summary of comments received on the proposal) are published in the Federal Register, the government’s official publication for making public the regulations and legal notices issued by federal agencies. The act and regulations require the Service to provide an opportunity for public participation in the rulemaking process, notify affected states and local jurisdictions and invite comments from them and other interested parties, notify newspapers and professional journals, and hold at least one public hearing, if requested, within 45 days of publishing the proposal. Additionally, Service procedures provide for listing and critical habitat decisions to be reviewed internally to help ensure that the professional judgment that the Service’s scientists exercise when weighing and interpreting the collected data is sound and conforms to contemporary scientific theories and principles. The process to list a species begins either through a petition from an individual, group, or state agency or through the initiative of the Service (see fig. 3). When a petition is filed to list a species, the Service provides a copy of the petition to, and requests information from, appropriate state agencies and affected tribal governments. The Service uses the information that it receives from these parties (or that which is contained in the petition or otherwise readily available) to make its initial determination as to whether a species may be threatened or endangered, and if so, to proceed with data gathering and analysis. The act requires the Service to make this determination generally within 90 days of receiving the petition. If the Service determines that it should proceed, it conducts a “status review”—a review of all the available information on a species—to determine whether the species warrants protection under the act. To conduct the status review, the Service solicits comments and requests information from the general public (by publishing a notice in the Federal Register) and contacts affected local, state, tribal and federal agencies; interested conservation or industry groups; and scientific organizations or professionals interested in and/or knowledgeable about the species. The Service may also fund field surveys, museum research, and literature searches in order to compile available information. Service scientists who conduct status reviews told us that they often work closely with experts from other government agencies, academia, and elsewhere to help gather and interpret information. In some instances, the Service initiates a review of a species without a petition, for which it conducts a candidate assessment—similar to a status review—to identify available information. Within 12 months of receiving a petition for which the Service proceeded with a status review, the Service must determine whether the species’ listing is warranted. If a Service field office makes an initial determination that the listing is warranted, it prepares a proposed rule for publication in the Federal Register. Before the proposed rule is published, a draft receives considerable internal review by officials in the Service’s field, regional, and headquarters offices. The review by officials in the field and regional offices helps ensure the exercise of sound professional judgment. The field office that is responsible for the listing provides the appropriate regional office with the draft of the proposed rule and all supporting scientific information. Officials in the regional office review the proposed rule to ensure that scientific information supports the proposed rule. Regions are responsible for ensuring that the proposed rule is scientifically accurate and biologically and legally sound. Regional officials told us that the review is an opportunity for the region to identify information gaps and issues concerning how the information supports the conclusions. At the Service’s headquarters, the draft proposed rule is reviewed to ensure that it is consistent with other listing rules and complies with national policies. Either the Director of the Fish and Wildlife Service or the Assistant Secretary for Fish and Wildlife and Parks approves all proposed rules before publication. Upon publication, the public has at least 60 days to provide comments on a proposed rule. The Service may extend the public comment period and/or reopen it at a later date. Service officials told us that the public comment period is an opportunity to reach biologists, scientists, academicians, and advocacy groups that the Service may not have contacted previously. The Service also holds public hearings, if requested. At the end of the public comment period, the Service reevaluates all the data, including the comments received since the proposal was published, to determine whether the listing is still warranted. If not, the proposal will be withdrawn. The Service must publish its final decision within 12 months of its proposal. In cases when experts disagree on the accuracy or sufficiency of the available data concerning the proposed listing, or the release of additional information that may affect the outcome of the petition is expected, the proposal may be extended 6 months beyond the normal 12- month time frame. In the event that the listing is warranted, the Service prepares a final rule, incorporating appropriate changes based on the information received during the comment period. Final rules are subject to the same internal review process as proposed rules and are approved by either the Director of the Fish and Wildlife Service or Assistant Secretary for Fish and Wildlife and Parks before being published. The procedures for designating critical habitat are similar to those for listing a species. However, in designating critical habitat, the Service must also take into consideration the economic and other impacts of specifying any particular area as critical habitat. The Assistant Secretary of Fish and Wildlife and Parks approves critical habitat designations. Officials at all levels of the agency demonstrated familiarity with the requirements of the review process and stated that they believe it provides the general guidelines necessary to ensure the best available data are identified and properly interpreted. Field office officials noted that proposed and final rules are challenged internally to ensure they can withstand public scrutiny and that while rulemakings are initiated at the field level, extensive review ensures that the entire agency is on board before anything is finalized. Scientists and other agency personnel told us that they use the process to test the validity of their listing and critical habitat decisions. Some officials emphasized the crucial role that the experience and expertise of the Service’s scientists play in ensuring that listing and critical habitat decisions are based on the best available science. Peer review is considered to be the most reliable tool to ensure that quality science will prevail over social, economic, and political considerations in the development of a particular product or decision.