a

GAO

United States General Accounting Office

Report to Congressional Requesters

August 2003 ENDANGERED 

SPECIES

Fish and Wildlife 

Service Uses Best 

Available Science to 

Make Listing 

Decisions, but 

Additional Guidance 

Needed for Critical 

Habitat Designations

GAO-03-803
The Endangered Species Act requires the U.S. Fish and Wildlife Service to 

identify, or “list,” species that are at risk of extinction and provide for their 

protection. The act also generally requires the Service to designate critical 

habitat—habitat essential to a species’ conservation—for each listed species.

The Service must use the best available science when making listing and 

critical habitat decisions. 

The Service’s policies and practices generally ensure that listing and critical 

habitat decisions are based on the best available science. The Service 

consults with experts and considers information from federal and state 

agencies, academia, other stakeholders, and the general public. Decisions 

are subject to external “peer review” and extensive internal review to help 

ensure that decisions are based on the best available science and conform to 

contemporary scientific principles. 

External reviews indicate that the Service’s listing and critical habitat 

decisions generally have scientific support, but concerns over the adequacy 

of critical habitat determinations remain. Listing decisions are often 

characterized as straightforward, and experts, peer reviewers, and others 

generally support the science behind these decisions. Critical habitat 

designations, on the other hand, are more complex and often require 

additional scientific and nonscientific information. As a result, peer 

reviewers often expressed concern about the specific areas designated, 

while other experts expressed concerns about the adequacy of the data 

available to make designations. 

The Service’s critical habitat program has been characterized by frequent 

litigation. Specifically, the Service has lost a series of legal challenges that 

will require significant resources for the next 5 fiscal years to respond to 

court orders and settlement agreements for designating critical habitat. As a 

result, the Service is unable to focus resources on activities it believes 

provide more protection to species than designating critical habitat. While 

the Service recognizes that it has lost control of the program, it has yet to 

offer a remedy. Without taking proactive steps to clarify the role of critical 

habitat and how and when it should be designated, the Service will continue 

to have difficulty effectively managing the program. 

Recent concerns about the U.S. 

Fish and Wildlife Service’s 

(Service) endangered species 

listing and critical habitat decisions 

have focused on the role that 

“sound science” plays in the 

decision-making process—whether 

the Service bases its decisions on 

adequate scientific data and 

properly interprets those data. In 

this report, GAO assesses the 

extent to which (1) the Service’s 

policies and practices ensure that 

listing and critical habitat decisions 

are based on the best available 

science and (2) external reviewers 

support the scientific data and 

conclusions that the Service used 

to make those decisions. In 

addition, GAO highlights the nature 

and extent that litigation is 

affecting the Service’s ability to 

effectively manage its critical 

habitat program. 

Because the Service’s critical 

habitat program faces serious 

challenges, including potential legal 

challenges and questions regarding 

the role of critical habitat in 

species conservation, GAO is 

recommending that the Service 

provide clear strategic direction for 

the critical habitat program, in a 

specified time frame, by identifying 

the issues affecting the Service’s 

ability to effectively manage the 

program and recommending 

policy/guidance, regulatory, and/or 

legislative changes necessary to 

address these issues. 

www.gao.gov/cgi-bin/getrpt?GAO-03-803.

To view the full product, including the scope 

and methodology, click on the link above. 

For more information, contact Barry T. Hill at 

(202) 512-3841 or hillbt@gao.gov. 

Highlights of GAO-03-803 a report to 

congressional requesters 

August 2003 

ENDANGERED SPECIES 

Fish and Wildlife Service Uses Best 

Available Science to Make Listing 

Decisions, but Additional Guidance 

Needed for Critical Habitat Designations 
Page i GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Contents

Letter 1

Results in Brief 3

Background 5

Procedures Are in Place to Ensure That Listing and Critical Habitat 

Decisions Are Based on the Best Available Science 9

Peer Reviewers and Others Conclude that Most Listing Decisions 

Are Based on Best Available Science, but Concerns about Critical 

Habitat Decisions Remain 19

The Service Has Failed to Address Known Problems with the Critical 

Habitat Program 32

Conclusion 36

Recommendation for Executive Action 36

Agency Comments 36

Appendixes

Appendix I: Objectives, Scope, and Methodology 38

Appendix II: Overview of The Endangered Species Act 42

Listing Species as Endangered or Threatened 43

Critical Habitat 44

Recovery Plans 45

Consultations with Federal Agencies 45

Habitat Conservation Plans 47

Appendix III: Peer Reviewers’ Responses to Listing and Critical Habitat 

Decisions for Fiscal Years 1999 through 2002 48

Appendix IV: The Nature of Scientific Controversy Surrounding Listing 

and Critical Habitat Decisions 58

Listing 58

Critical Habitat 62

Appendix V: GAO Contact and Staff Acknowledgments 68

GAO Contact 68

Staff Acknowledgments 68

Table Table 1: Species Delisted on the Basis of New Information 26

Figures Figure 1: Number of Domestic Species Listed as Threatened or 

Endangered, 1981 through 2002 7
Contents

Page ii GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Figure 2: Number of Domestic Species with Critical Habitat, 1981 

through 2002 8

Figure 3: The Service’s Process to List Species as Threatened or 

Endangered 11

Figure 4: Peer Review Response Rates for Listing and Critical 

Habitat Decisions, Fiscal Years 1999 through 2002 18

Figure 5: Canada lynx 61

Figure 6: California red-legged frog 64

Figure 7: Southwestern willow flycatcher 66

This is a work of the U.S. government and is not subject to copyright protection in the 

United States. It may be reproduced and distributed in its entirety without further 

permission from GAO. However, because this work may contain copyrighted images or 

other material, permission from the copyright holder may be necessary if you wish to 

reproduce this material separately.
Page 1 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

United States General Accounting Office

Washington, D.C. 20548

A

August 29, 2003 Letr

The Honorable Bob Goodlatte

Chairman, Committee on Agriculture

House of Representatives

The Honorable Scott McInnis

Chairman, Subcommittee on Forests and Forest Health

Committee on Resources

House of Representatives

The Honorable Richard Pombo

Chairman, Committee on Resources

House of Representatives

The Congress enacted the Endangered Species Act in 1973 to protect plant 

and animal species whose survival is in jeopardy. The U.S. Fish and 

Wildlife Service (Service) is responsible for implementing the act for 

freshwater and land species.1

 For many years, the act, its implementation, 

and the Service have served as lightning rods in the ongoing national 

debate concerning the tradeoffs between economic, social, and 

environmental values. The act requires the Service to list as endangered 

any species facing extinction throughout all or a significant portion of its 

range and to list as threatened any species likely to become endangered in 

the foreseeable future. The Service must make decisions to list species 

solely on the basis of the best available scientific and commercial data, 

such as biological or trade data obtained from commercial publications. 

The act also generally requires the Service to designate critical habitat—

habitat essential to a species’ conservation—when listing a species; the 

loss of habitat is often the principal cause of species decline. For critical 

habitat decisions, the act again requires the Service to consider the best 

available scientific data, but also requires the Service to consider the 

economic impact and other relevant impacts of designating particular areas 

as critical habitat. The Service is also required to develop a plan to recover 

1

The Department of the Interior, which has responsibilities for implementing the 

Endangered Species Act, has delegated its responsibility to the U.S. Fish and Wildlife 

Service, which established an endangered species program to implement the requirements 

of the act. The Department of Commerce, which has delegated its responsibilities to the 

National Marine Fisheries Service, is responsible for implementing the act for anadromous 

fish and most marine species. This report does not address the National Marine Fisheries 

Service program.
Page 2 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

the listed species to the point that it is no longer threatened or endangered, 

an achievement marked by its removal, or delisting, from the list of 

threatened or endangered species. 

Recent concerns about the Service’s listing and critical habitat decisions 

have focused on the role that “sound science” plays in the decision-making 

process and whether the Service bases its decisions on adequate scientific 

data and properly interprets those data. Critics of the decisions warn that 

improper listing and critical habitat decisions may cause social and 

economic disruption and divert funding and attention away from other 

species truly facing extinction. In addition to concerns about its use of 

science, the Service is having difficulty managing the listing and critical 

habitat programs, in part because of extensive litigation. Currently, the 

Service is experiencing a significant backlog of decisions to list species and 

to designate critical habitat. The Service has identified more than 200 

species that qualify for listing but for which the listing process has not yet 

begun because of resource limitations or higher-priority actions being 

taken for other species. 

You asked us to assess the Service’s consideration and use of science in its 

decisions to list species as threatened or endangered and to designate 

critical habitat. Specifically, we reviewed the extent to which (1) the 

Service’s policies and practices ensure that listing and critical habitat 

decisions are based on the best available science and (2) outside reviewers 

support the scientific data and conclusions that the Service uses to make 

listing and critical habitat decisions. In addition, in performing our work, 

we identified certain factors that could continue to affect the Service’s 

ability to effectively manage its critical habitat program. Our report 

highlights the nature and extent of those problems as well.

In meeting our objectives, we examined decision documents for the 101 

listing and critical habitat decisions that the Service issued during fiscal 

years 1999 through 2002. There were 64 listing decisions and 37 critical 

habitat decisions covering 108 and 36 species, respectively. To evaluate the 

adequacy of the science used to support these decisions, we reviewed (1) 

the Service’s policies, procedures, and practices for making listing and 

critical habitat decisions; (2) the responses of peer reviewers who 

commented on 79 listing and critical habitat actions; and (3) judicial 

decisions related to listing and critical habitat actions decided during fiscal 

years 1999 through 2002. We also interviewed staff at seven field and 

regional offices and at Service headquarters to help understand the 

Service’s decision-making process. We interviewed individuals with 
Page 3 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

academic, industry, and conservation organizations and the National 

Academy of Sciences to better understand why some of the Service’s 

decisions are controversial. In this report, we define “science” as the 

collection and interpretation of biological information, such as 

identification of the species and its habitat needs. At no point in our review 

did we attempt to directly evaluate the scientific analysis on which the 

Service based its listing and critical habitat decisions. A more detailed 

description of our scope and methodology is presented in appendix I.

Results in Brief The Service’s policies and practices generally ensure that listing and critical 

habitat decisions are based on the best available science. In making listing 

and critical habitat decisions, the Service consults with experts both inside 

and outside the federal government and considers studies or other data 

from federal and state agencies, other stakeholders, and the general public. 

Both proposed decisions and final decisions are subject to internal review 

at field, regional, and headquarters offices to help ensure that the 

professional judgment is sound and conforms to contemporary scientific 

theories and principles. In addition, the Service also has a policy to ask at 

least three independent scientific experts in a relevant field to “peer 

review” proposed decisions to list species or designate critical habitat to 

help ensure that decisions are based on the best available science. 

Reviews by outside experts and others indicate that the Service’s listing 

and critical habitat decisions are generally based on the best available 

science, but that there are concerns over the adequacy of the data used to 

support critical habitat designations. For listing decisions, peer reviewers 

overwhelmingly supported the science behind the decisions the Service 

issued between fiscal years 1999 and 2002. Additionally, during that same 

time period, the courts overturned few listing decisions because the 

Service relied on faulty or inadequate science. Further evidence that listing 

decisions are scientifically sound is provided by the fact that only 10 of the 

more than 1,200 domestic listed species have been delisted after new 

scientific information surfaced that indicated the original listing was not 

warranted. In contrast, while external reviews indicate that most critical 

habitat decisions are based on the best available science, experts and 

others we spoke to expressed concerns over the adequacy of the 

information available to support the designations. While peer reviewers 

generally agreed with the science supporting the Service’s critical habitat 

decisions, they often also provided suggestions for modifying the 

designations. In three decisions, peer reviewers disagreed with the 

Service’s designation of critical habitat, stating that the Service had 
Page 4 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

insufficient information to make the decision. Although the Service has 

frequently lost legal challenges over its critical habitat designations, courts 

have overturned few of the Service’s critical habitat decisions as not 

supported by the best available science. Instead, most of the challenges 

dealt with nonscience issues, such as the Service’s failure to designate 

habitat for a listed species.

Key court decisions have invalidated certain practices adopted by the 

Service, causing its critical habitat program to be dominated by litigation. 

In 1997, the Service lost a lawsuit challenging its practice of not designating 

critical habitat for many species; the Service did not designate critical 

habitat because it believes it conveys little additional protection to listed 

species. This suit led to numerous other suits, resulting in court orders 

directing the Service to designate critical habitat for many previously listed 

species. In 1999, the Service announced that its system for designating 

critical habitat was not working and that critical habitat litigation and 

related court orders were consuming much of the program’s resources. To 

remedy the situation, the Service announced its intention to develop 

guidance and/or regulations to clarify the role of critical habitat in 

endangered species conservation and to streamline the process used to 

designate critical habitat. However, such guidance and clarification were 

never issued, and the Service continues to follow the same system that it 

recognizes is unworkable. In 2001, the Service lost another lawsuit, which 

challenged the adequacy of the economic analyses the Service used to 

support its critical habitat designations. These two lawsuits, and 

subsequent legal challenges based on similar issues, have come to 

dominate the Service’s critical habitat program. In 2002, we reported on 

problems facing the critical habitat program and recommended that the 

Service expedite its efforts to issue guidance for the program; however, the 

Service has yet to do so.2

 If the Service does not take proactive steps to 

clarify the role of critical habitat and how and when it should be 

designated, we believe it will continue to have difficulty effectively 

managing the program. Therefore, we recommend that the Service—

through guidance, regulations, or other policy tools—provide clear 

strategic direction for the critical habitat program in order to provide the 

greatest conservation benefit to threatened and endangered species in the 

2

U.S. General Accounting Office, Endangered Species Program: Information on How 

Funds Are Allocated and What Activities Are Emphasized, GAO-02-581 (Washington, D.C.: 

June 25, 2002).
Page 5 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

most cost-effective manner. The Department of the Interior did not 

respond to our request to comment on the recommendation. 

Background 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.3

 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:4

• present or threatened destruction, modification, or curtailment of a 

species habitat or range;

• overuse for commercial, recreational, scientific, or educational 

purposes;

• disease or predation;

• inadequacy of existing regulatory mechanisms; or

• other natural or manmade factors affecting a species’ continued 

existence.

3

16 U.S.C. §1533(b).

4

16 U.S.C. §1533(a)(1). The Service must also use these factors to determine if a species 

should be reclassified from endangered to threatened or vice versa and, in some instances, 

whether it should be delisted. The Service would not take into consideration these factors 

to delist a species because it is extinct. 
Page 6 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

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.5

 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.

5

The totals count a species or subspecies only one time, even if it occurs on the list more 

than once. A species or subspecies could be listed more than once if, for example, it was 

threatened in one part of its range and endangered in the rest of its range (these are known 

as “dual status species”). Similarly, a species or subspecies might occur on the list more 

than once if more than one distinct population segment of a species is listed. Distinct 

population segments are populations of vertebrate species that are discrete, for example, 

because they are geographically separated from other populations of the species.
Page 7 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Figure 1: Number of Domestic Species Listed as Threatened or Endangered, 1981 through 2002

Note: There have been 25 domestic species delisted since the inception of the act. These species are 

not included in the figure. In addition, 16 species have been reclassified from endangered to 

threatened.
Page 8 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

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.6

 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. 

Figure 2: Number of Domestic Species with Critical Habitat, 1981 through 2002

Note: Some species may have had critical habitat designated more than one time; the graph includes 

only the first time that critical habitat was designated. 

6

16 U.S.C §1532(5). 
Page 9 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

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.7

 “Taking” or “take” means to harass, 

harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect a listed 

species.8

 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.) 

Procedures Are in 

Place to Ensure That 

Listing and Critical 

Habitat Decisions Are 

Based on the Best 

Available Science

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. 

7

16 U.S.C. §1538(a)(1)(B), (C). The Endangered Species Act prohibits the taking of 

endangered, but not threatened, species. However, the act authorizes the Service to, by 

regulation, prohibit the taking of a threatened species. The Service has issued a regulation 

extending the take prohibitions to threatened species, except for those covered by a specific 

rule, exemption, or permit. See 50 C.F.R. §17.31.

8

16 U.S.C. §1532(19). 
Page 10 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Internal Decision-Making 

Process Helps Ensure That 

the Service Uses Best 

Available Science in Making 

Decisions 

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.9

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).10 

9

The Department of the Interior has recently issued a code of scientific conduct to be used 

by all Interior scientists—including the Service—to ensure that all research and analysis is 

conducted according to the highest standards of the scientific community.

10The Service uses the same process to delist or to reclassify a species from endangered to 

threatened or vice versa. Either action may be initiated through a petition or by the 

Secretary of the Interior. 
Page 11 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Figure 3: The Service’s Process to List Species as Threatened or Endangered
Page 12 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

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.11 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.12 The review by officials in the field and 

11The Service bases its determination on whether or not there is “substantial” information to 

proceed. Substantial information is defined by Service regulations as information that 

would lead a reasonable person to believe that the measure proposed in the petition may be 

warranted. 50 C.F.R. § 424.13(b).

12If the field office determines the petition is not warranted or is warranted but precluded, 

the Service will issue a notice in the Federal Register. This notice goes through a similar 

internal review process. A “warranted but precluded” finding is made when the petitioned 

action is precluded from immediate action by other, higher priority actions. The Service 

reevaluates warranted but precluded petitions every 12 months until either a proposed rule 

is issued or a "not warranted" finding is made. 
Page 13 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

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. 
Page 14 GAO-03-803 Additional Guidance Needed for 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. 

Outside Experts Review 

Proposed Rules 

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. Peer review—a 

routine component of science—can substantially enhance the quality and 

credibility of the scientific or technical basis for a decision. For regulatory 

decisions, peer review can provide for independent and expert analysis to 

complement the adversarial and political nature of rulemaking. 

While many federal agencies were already using peer review, the Office of 

Management and Budget (OMB) issued guidance in 2002 recommending 

that federal agencies utilize formal, independent external peer review (peer 

review by individuals outside of the agency) to ensure the quality of data 

and analytic results disseminated to the public.13 It also recommended that 

peer reviewers be selected primarily on the basis of their technical 

expertise, that they disclose any source of bias (either prior technical or 

policy positions or sources of personal and institutional funding from 

which they may benefit), and that peer review be conducted in an open and 

rigorous manner. 14 

1367 Fed. Reg. 8452 (Feb. 22, 2002). 

14Office of Management and Budget, Memorandum for the President’s Management 

Council, Sept. 20, 2001.
Page 15 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Federal agencies have adopted a variety of peer-review practices, 

depending on the nature of the product or decision under review. As we 

reported in 1999, peer-review practices at federal agencies vary according 

to their intended use and form.15 According to OMB’s 2002 guidance, 

agencies should tailor the rigor and intensity of peer review in accordance 

with the significance of risk or management implications of the information 

involved. The form of peer review can range from informal consultations 

with agency colleagues not involved in the earlier stages of the project to 

formal external advisory panels, which can span several years and cost 

thousands of dollars. In addition, for each different form of peer review, 

there are multiple variations—the amount of time allocated for the review, 

the number of reviewers, and whether the review occurs internally or 

externally—all of which affect the overall time and cost required to 

conduct a review. 

In addition to its internal decision-making processes, the Service uses 

external peer review of listing and critical habitat decisions to ensure that 

the best biological and commercial information is being considered. The 

Service’s peer-review policy requires officials to solicit the opinions of 

three appropriate and independent experts regarding scientific data and 

assumptions supporting listing and critical habitat decisions.16 Peer 

reviewers are selected at the discretion of the field office scientists 

responsible for developing listing and critical habitat decisions. The 

reviewers, who may come from the academic and scientific community, 

tribal and other Native American groups, federal and state agencies, and/or 

the private sector, are selected on the basis of their independence and 

expertise on the species being considered, similar species, the species’ 

habitat, or other relevant subject matter. The Service’s scientists may ask 

peer reviewers to critique specific aspects of the proposed rule, such as the 

Service’s interpretation of a particular study, or they may ask reviewers to 

comment on the rule in its entirety. 

The Service’s peer-review policy generally appears to be appropriate for the 

circumstances in which it is used. Although other agencies may use more 

rigorous forms of peer review, such as convening a peer-review panel or a 

15U.S. General Accounting Office, Federal Research: Peer Review Practices at Federal 

Science Agencies Vary, GAO/RCED-99-99 (Washington, D.C.: Mar. 17, 1999).

1659 Fed. Reg. 34270 (July 1, 1994). The Service is currently drafting interim peer review 

guidance that will provide objectives and procedures for implementing the 1994 peer review 

policy. It does not have an estimated date when it will issue permanent guidance.
Page 16 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

science advisory board, the Service’s peer-review process allows the 

Service to make listing and critical habitat decisions under relatively short 

time frames (the Service usually asks peer reviewers to perform their 

review during the public comment period—normally 60 days—while a 

peer-review panel may span several months or years). However, to help 

ensure the identification of complete and current information on a species 

and its habitat, the Service may contact experts during the status review. In 

addition, any decisions that are issued as “final” rules can later be 

reconsidered as circumstances warrant or new information becomes 

available. In fact, a species can be delisted if new information surfaces 

indicating that the original decision to list was not warranted.

One limitation that the Service faces in getting an independent review is the 

scarcity of experts on a particular species. For example, in some instances, 

the most qualified experts to peer review a decision may have authored 

some of the studies that the Service used to support its decision, forcing 

the Service to balance expertise with independence. However, according 

to a National Academy of Sciences report that reviewed the Environmental 

Protection Agency’s use of peer review for similar actions, to choose an 

individual to peer review who is both an expert and independent might be 

impossible, or might not promote the best possible review.17 In such cases, 

an appropriate balance of views may be sought to ensure that different 

interpretations on the scientific and technical merit of a decision are taken 

into consideration. Such cases should, however, be fully disclosed. Other 

organizations have developed procedures for assessing the independence 

of peer reviewers, ranging from simply requiring peer reviewers to disclose 

any potential bias, to using third parties to identify peer reviewers based, in 

part, on their independence. Service officials told us that they have not 

adopted a formal procedure to assess peer reviewers’ independence, and 

the Service does not publicly disclose in the Federal Register potential 

conflicts or prior involvement by its peer reviewers when the Service 

publishes the final rule.

17National Research Council, Strengthening Science at the U.S. Environmental Protection 

Agency: Research-Management and Peer-Review Practices (Washington D.C.: National 

Academy Press, 2000).
Page 17 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

The Service generally complied with its peer-review policy of soliciting 

peer review from at least three reviewers during fiscal years 1999 through 

2002. During this time, the Service solicited three or more peer reviewers 

in 94 out of the 100 listing and critical habitat decisions it made.18 In three 

instances the Service solicited fewer than three peer reviewers, and in 

three other instances documentation was unavailable to indicate how many 

reviewers were asked.19 (See app. III for a complete list of the decisions 

with the number of peer reviewers solicited, the number that responded, 

and how they responded.) 

While the Service generally complied with its policy to seek peer reviewers, 

reviewers often did not respond. As shown in figure 4, the Service received 

responses from three or more peer reviewers in 38 decisions for which it 

solicited at least three peer reviewers. It received either one or two 

responses in 41 decisions, and no responses in 15 decisions.

18Although the Service published 101 listing and critical habitat decisions during fiscal years 

1999 through 2002, the decision to list as threatened the Lake Erie water snakes (64 Fed. 

Reg. 47126 (Aug. 30, 1999)) is not included in this analysis because the comment period for 

the proposed rule opened before the Service’s peer review policy became effective. 

19 In two additional instances, documentation is also unavailable to indicate how many 

reviewers were asked but there is documentation that the number of respondents was 

greater than two. In these instances, we credited the Service with having solicited at least 

three peer reviewers. 
Page 18 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Figure 4: Peer Review Response Rates for Listing and Critical Habitat Decisions, 

Fiscal Years 1999 through 2002

Note: Response rates are for the 94 decisions for which the Service solicited at least 3 peer reviewers. 

Overall, the Service asked 422 experts to peer review the 100 listing and critical habitat decisions 

made during fiscal years 1999 through 2002 and received 212 responses (50 percent response rate).

Field office scientists, as well as an expert on peer review, reported a 

variety of reasons for the limited number of responses, including (1) the 

potential peer reviewers had busy schedules and felt constrained by the 

short time frames allotted to conduct the review, and (2) the potential 

reviewers were unwilling to conduct peer review either because they did 

not want to become involved in a controversial decision or because they 

did not want to work without compensation. In addition, the field office 

scientists reported that potential peer reviewers may not be inclined to 

conduct peer review because they found nothing to criticize or had already 

provided comments at an earlier stage of the decision, such as during the 

status review.

Recognizing the importance of peer review, some regional and field offices 

have taken steps to increase the number of respondents. For example, 

some field offices contact potential peer reviewers in advance, rather than 

initiating contact just before the decision is open for peer review; others 

maintain communication with the peer reviewers throughout the process. 

For example, the Pacific Islands field office in Honolulu, Hawaii, has 

assigned an administrative staff person to initiate phone calls and E-mails 

to help remind and encourage peer reviewers to respond. This staff person 
Page 19 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

also monitors the implementation of the peer-review policy and tracks 

results. In order to increase the likelihood that at least three peer 

reviewers respond to a request, some field offices request peer reviews 

from more than three individuals. Field office scientists suggested other 

ways to increase the response rate, such as providing monetary 

compensation, using a third party to select and coordinate peer review, 

narrowing the scope of the review, and providing more time for review. 

Peer Reviewers and 

Others Conclude that 

Most Listing Decisions 

Are Based on Best 

Available Science, but 

Concerns about 

Critical Habitat 

Decisions Remain

External reviews of listing and critical habitat decisions indicate that most 

decisions are generally scientifically supported, but concerns about the 

adequacy of critical habitat determinations remain. Listing decisions are 

often characterized as straightforward, requiring the Service to answer 

only a “yes or no” question as to whether a species warrants inclusion on 

the threatened or endangered list. Critical habitat designations, on the 

other hand, are more complex and often require further information on the 

species’ habitat requirements and other management considerations. Peer 

reviewers often expressed concerns about the specific areas designated as 

critical habitat, while other experts expressed concerns about the 

adequacy of the information available to make the designation.

Little Scientific 

Disagreement Surrounds 

Listing Decisions 

Experts and others have found most of the Service’s listing decisions to be 

scientifically supported. Experts knowledgeable about the Endangered 

Species Act and recent studies assessing the Service’s use of science in 

making listing decisions concur that the Service’s listing decisions are 

generally supported. Similarly, experts not affiliated with the Service have 

peer-reviewed proposals to list species and overwhelmingly supported the 

Service’s decisions. The courts have overturned few listing decisions on the 

basis of inadequate science, and the Service has delisted few species on the 

basis of new information that suggested that protection under the act was 

not originally warranted. 

Experts and Others Generally 

Support Service Listing 

Decisions

Experts, Service officials, and others knowledgeable about the Endangered 

Species Act largely agree that most listing decisions have been relatively 

straightforward and scientifically supported. Experts and others we spoke 

to generally agreed that most listed species probably deserved being listed 

under the current standard for best available scientific information. For 

example, several attorneys, who represent the regulated community in 

challenges to the Service’s decisions, stated that, given the Service’s short 

time frames and limited resources, the science used to support most listing 
Page 20 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

decisions did not present a significant problem. However, these attorneys 

and others contend that the “best available data” standard does not provide 

enough certainty that a species is threatened or endangered and suggest 

that a more stringent standard should be developed. On the other hand, 

interested parties representing a diverse set of interests raised concerns 

that Service officials at the Headquarters level are succumbing to political 

pressures to not list species despite support from regional and field 

scientists who believe evidence shows that listing is warranted. Service 

scientists told us they believe many listed species have low populations 

and/or face clearly identified threats, indicating that the species are at risk. 

They said that many listing decisions have been made to protect species 

native to a specific area, with a narrow range, or for which substantial 

scientific information was already available or easy to collect. On the other 

hand, the scientists noted that collecting information becomes more 

difficult and costly when a wide-ranging species may be at risk. 

Additionally, several scientific disagreements regarding listing decisions 

have surfaced in recent years, mostly concerning whether the amount of 

information available at the time a decision is made suffices as a basis for a 

decision. (See app. IV for information on the nature of scientific 

controversy surrounding the Service’s decisions to list species.) Finally, 

many of the experts we spoke with had concerns about the science used to 

support other aspects of the act, such as recovery actions or consultations 

with federal entities on proposed actions that could potentially harm a 

listed species. 
Page 21 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Several studies have supported the Service’s use of science in making 

listing decisions. The Ecological Society of America—a professional 

society of ecologists representing ecological researchers in more than 60 

countries—released a study on the use of science in achieving the goals of 

the act that concluded that the major problem with the listing process has 

been its slowness rather than the quality of the listing decisions.20 The 

National Research Council (NRC) reached similar conclusions in a 1995 

report, finding that many of the conflicts and disagreements over the 

Endangered Species Act do not appear to be based on scientific issues.21 

More recently, in 2002, NRC reviewed the genetic evidence used to support 

one particular listing decision, the listing of the Gulf of Maine Atlantic 

salmon distinct population segment.22 It concluded that Maine salmon are 

genetically distinct from other salmon, supporting the Service’s decision to 

list the species. 

Peer Reviewers Overwhelmingly 

Support the Service’s Use of 

Science in Making Listing 

Decisions

The Service received 143 peer-review responses for 54 of the 63 listing 

decisions finalized between fiscal years 1999 and 2002 and no responses for 

the remaining 9 decisions (see app. III). In 48 of these decisions, reviewers 

providing comments unanimously agreed with the Service’s scientific 

conclusions or otherwise indicated support for the decision to list the 

species. In two decisions, the Service reported that one of the peer 

reviewer’s opinions was “neutral,” and the rest of the opinions were 

supportive. In two other decisions, we were unable to determine the nature 

of one of the peer reviewer’s response. Peer reviewers disagreed with the 

Service in the following two decisions: 

• Alabama sturgeon. One of the five reviewers to provide comments on 

the proposal to list the Alabama sturgeon, a freshwater fish historically 

found throughout the Mobile River basin of Alabama and Mississippi, 

disagreed with the Service’s proposed listing determination. While the 

reviewer did not directly respond to the Service’s request for peer 

review, he did provide comments at one of the public hearings regarding 

20Carroll, R., et al., Strengthening the Use of Science in Achieving the Goals of the 

Endangered Species Act: An Assessment by the Ecological Society of America. Ecological 

Applications, 6(1): 1-11 (1996).

21National Research Council, Science and the Endangered Species Act (Washington D.C.: 

National Academy Press, 1995) 202.

22National Research Council, Genetic Status of Atlantic Salmon in Maine: Interim Report 

from the Committee on Atlantic Salmon in Maine (Washington D.C.: National Academy 

Press, 2002).
Page 22 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

the proposed rule. The reviewer argued that the Alabama sturgeon was 

not a valid species given the fish’s morphological (i.e., physical 

appearance such as color pattern, shape, and scale patterns) and genetic 

evidence. The other four reviewers responding to the proposed rule 

supported the validity of the Alabama sturgeon as a species. 

• Desert yellowhead. One of two reviewers who provided comments on 

the proposed rule to list the desert yellowhead (a flowering plant that 

occurs in Wyoming) agreed that the species was rare and in need of 

protection, but did not agree that listing the species under the act was 

the appropriate mechanism. The other reviewer supported listing the 

plant. 

Courts Have Overturned Few 

Listing Decisions on the Basis of 

Inadequate Science 

The Service’s actions and inactions under the act are frequently challenged 

in the courts. In hearing such challenges, courts must defer to agencies in 

judging actions, such as listing decisions, and must not substitute their 

judgment for an agency’s, especially on technical matters.23 As a result, 

courts will uphold an agency decision when it is evident that the agency 

considered the relevant facts and articulated a rational connection between 

those facts and its decision.24 Partly because of the deference granted to 

the Service in making listing determinations, most litigation has not 

directly challenged the Service’s use of science. Instead, according to an 

official from the Department of the Interior’s Office of the Solicitor, most 

litigation revolves around definitional or procedural issues, such as the 

Service’s failure to meet statutory time frames. The official said that 

litigants often challenge decisions on nonscientific aspects of the act 

because they feel this provides them with a stronger case. Thus, the fact 

that the courts have rarely ruled against the Service on the basis of 

inadequate science is not necessarily an affirmation that the Service used 

the best available science.

Based on a review of federal court cases decided during fiscal years 1999 

through 2002, we identified 17 cases in which a court issued an opinion 

related to the Service’s listing decisions. The Service lost 11 of these cases, 

mostly because it failed to take certain actions regarding decisions to list or 

not to list a species within the time allotted by the act. However, the courts 

23Baltimore Gas and Electric Co. v. Natural Resources Defense Council, 462 U.S. 87, 103 

(1983); Kleppe v. Sierra Club, 427 U.S. 390, 412 (1976).

24Baltimore Gas and Electric Co., 462 U.S. at 105.
Page 23 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

overturned listing decisions on the basis of issues related to the use of 

scientific data in the following two cases:

• Sacramento splittail. In 2000, a federal court ruled that the decision to 

list the Sacramento splittail was not supported by the best scientific 

data available.25 The splittail is a large fish with a distinctive tail and is 

native to California’s Central Valley. Regional water authorities 

challenged the listing of the splittail on scientific grounds, asserting, 

among other things, that the Service ignored an important study 

indicating resiliency and an increasing abundance of the splittail. The 

court rejected the Service’s arguments that these data were not 

submitted in time to be considered and were irrelevant, and found there 

to be no indication that the Service considered substantial evidence that 

suggested that the splittail should not be listed. The court thus 

concluded that the Service had failed to consider all available data. The 

Service is in the process of reevaluating this listing rule.

• Westslope cutthroat trout. In 2002, a federal court ruled that the 

Service’s decision not to list the Westslope cutthroat trout was not 

supported by the best scientific data available.26 The Westslope trout is 

one of 14 subspecies of cutthroat trout native to streams in the western 

United States. In its decision not to list the trout, the Service identified 

hybridization (the breeding with other species of trout) as one of the 

threats to the species, but included these hybrid fish in the population 

considered for listing. The court noted that if hybridization were a 

“threat” to the species, it would seem logical that hybrid fish should not 

be included in the population under consideration. After explaining that 

the identification of the existing population of the trout was vital to the 

ultimate listing determination, the court found that the record failed to 

offer a rationale for including hybrid stocks in the population that it 

considered for listing, and concluded that the Service had ignored 

existing scientific data for assessing the degree of hybridization that 

may be appropriate to include in the population. The court remanded 

the case to the Service for reconsideration.

25San Luis v. Badgley, 136 F. Supp.2d 1136 (E.D.Cal. 2000).

26American Wildlands v. Norton, 193 F.Supp.2d 244 (D.D.C. 2002).
Page 24 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

The Service lost the following two cases because it failed to assess whether 

the species was imperiled throughout “a significant portion of its range.”27

• Flat-tailed horned lizard. In 2001, an environmental group successfully 

challenged the Service’s decision not to list the flat-tailed horned lizard, 

a small lizard found in desert lands in the southwestern United States. 28

In reaching its decision, the Service concluded that regardless of the 

threats to the lizard on private lands, large populations of the lizard and 

areas of its habitat were already protected under a conservation 

agreement on public lands and that the species was sufficiently 

protected from further threats. The court found that the Service should 

have performed an analysis to determine whether the private lands 

constituted “a significant portion of [the lizard’s] range” and, if so, 

whether the lizard was or would become extinct in that area. The court 

remanded the case to the Service for those determinations. 

• Queen Charlotte goshawk. In 2002, an environmental group successfully 

challenged the Service’s decision not to list the Queen Charlotte 

goshawk, a forest-dwelling bird of prey found throughout North 

America. 29 In reaching its decision, the Service considered the 

goshawk’s presence in southeast Alaska, the Queen Charlotte Islands, 

and Vancouver Island in Canada.30 The Service found that the goshawk 

was not threatened or endangered in southeast Alaska or the Queen 

Charlotte Islands, but the Service did not make a determination 

regarding the goshawk’s status on Vancouver Island. The Service 

contended that the goshawk’s status on Vancouver Island did not matter 

because that area did not represent a significant portion of the 

goshawk’s range. The decision in this case upheld the Service’s 

determination regarding southeast Alaska and the Queen Charlotte 

Islands, finding that the Service had properly used the best available 

27The Endangered Species Act defines an endangered species and a threatened species as a 

species that is endangered or threatened throughout all “or a significant portion” of its 

range. 16 U.S.C. §1532(6), (20). In fiscal year 2003, the Service lost another listing case on 

similar grounds. See Defenders of Wildlife v. Norton, 239 F.Supp.2d 9 (D.D.C. 2002). 

28Defenders of Wildlife v. Norton, 258 F.3d 1136 (9th Cir. 2001).

29Southwest Center for Biological Diversity v. Norton, 2002 WL 1733618, No. 98-934 (D.D.C. 

2002).

30The range to be considered is not limited to areas within the United States. Defenders of 

Wildlife v. Norton, 258 F.3d at 1145.
Page 25 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

science. However, the decision went on to conclude that Vancouver 

Island represented a significant portion of the goshawk’s range and that 

the case should be remanded to the Service to determine whether the 

goshawk was threatened or endangered on Vancouver Island. 

The Service Has Delisted Few 

Species on the Basis of New 

Scientific Information Showing 

That Listing Was Not Warranted 

In addition to removing recovered or extinct species from the list of 

threatened or endangered species, the Service can also delist a species if 

new information becomes available to show that protection under the act is 

not warranted. Typically, listing a species generates widespread attention 

to the species, additional funding for its study, and further research relating 

to the species or its habitat. As additional information is gathered, the 

Service or interested parties can initiate a delisting action if they believe 

the species no longer qualifies for listing. The Service follows similar 

rulemaking procedures to delist a species as for listing.

Since the inception of the Endangered Species Act, the Service has delisted 

few species. As of March 2003, the Service had delisted 25 threatened and 

endangered domestic species of the more than 1,200 listed.31 Of the 25 

delistings, 10 resulted from new information—4 because new information 

showed the species to be more widespread or abundant than believed at 

the time the species was listed, and 6 for taxonomic revisions, meaning that 

the species was found not to be unique, but was a hybrid or simply a 

population of another common species making it ineligible for listing (see 

table 1). The remaining 15 delistings resulted from recovery efforts (7), 

extinction (7), or an amendment to the act that made the species no longer 

qualify for listing protection (1).32

31An additional 8 foreign species have been delisted, 7 due to recovery and 1 due to 

erroneous data. 

32Amendments to the act in 1978 restricted protection for distinct population segments to 

vertebrates. The species listed was the Florida population of the Bahama swallowtail 

butterfly, and thus the act, as amended, required that the species be removed from the 

endangered species list. See 49 Fed. Reg. 34501 (Aug. 31, 1984).
Page 26 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Table 1: Species Delisted on the Basis of New Information

Species name Description Date listed Date delisted Reason delisted

Species more abundant or widespread

Dismal Swamp 

southeastern 

shrew

A small, longtailed shrew found 

in the 

southeastern U.S.

Sept. 26, 1986 Feb. 28, 2000 Analyses completed after the species was listed showed 

that the species is actually widely distributed and uses a 

wide variety of habitat types. 

McKittrick 

pennyroyal

A small herb 

native to the 

Guadalupe 

Mountains in 

southeastern New 

Mexico and 

northwestern 

Texas

July 13, 1982 Sept. 22, 1993 Since the time of listing, additional surveys have shown the 

plant to be more widespread and abundant than previously 

known. Further, management actions were taken by various 

federal agencies to provide protections to the plant. 

Tumamoc 

globeberry

A vine occurring in 

south-central 

Arizona and 

extending 

southward into 

Mexico

Apr. 29, 1986 June 18, 1993 Surveys and studies completed after the time of the listing 

showed that the range of the species is much larger than 

originally known and the plant was more common and 

requires less habitat-specific areas than was believed at the 

time of listing. 

Pine barrens 

treefrog, Florida 

population

A frog known to 

occur in Florida, 

Alabama, New 

Jersey, and the 

Carolinas

Nov. 11, 1977 Nov. 22, 1983 Subsequent studies completed after the time of listing 

revealed a number of new populations and a more 

extensive distribution of the species throughout Florida and 

Alabama. 

Taxonomic revision

Umpqua River 

cutthroat trout

A fish found in the 

Umpqua River 

basin in coastal 

Oregon

Sept. 13, 1996 Apr. 26, 2000 An expanded review subsequent to listing showed that this 

population is part of another larger population of trout that 

did not warrant listing.

Lloyd’s hedgehog 

cactus

A cactus primarily 

occurring in Texas 

and New Mexico

Oct. 26, 1979 June 24, 1999 Subsequent studies completed after the time of listing 

showed evidence indicating that the cactus is not a distinct 

species but rather is a hybrid. 

Cuneate bidens A flowering 

Hawaiian plant

Feb. 17, 1984 Feb. 6, 1996 Subsequent studies after the time of listing culminated in a 

taxonomic revision of the genus. The plant was determined 

to be no more than an outlying population of another 

common species, which is not significantly threatened.

Spineless 

hedgehog cactus

A cactus known to 

occur in 

southeastern Utah 

and southwestern 

Colorado

Nov. 7, 1979 Sept. 22, 1993 Subsequent to listing, several evaluations did not recognize 

the cactus as a distinct species and the consensus of 

botanists was that the cactus was only a form of another 

type of cactus which was much more widespread, occurring 

from Utah and Colorado south into central Mexico. 
Page 27 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Source: GAO analysis of U.S. Fish and Wildlife Service data.

Concerns Remain Over the 

Adequacy of Scientific 

Information Used in Making 

Critical Habitat Decisions

While external reviews indicate that the Service bases most critical habitat 

decisions on the best available science, concerns remain over the adequacy 

of the information available to support the decisions. Experts and others 

we spoke to explained that the amount of scientific information available 

on a species’ habitat needs often may be limited, affecting the Service’s 

ability to adequately define the habitat area required. Experts that peer 

reviewed proposed critical habitat designations generally supported the 

Service’s decisions, though many provided additional clarifications or 

suggestions. While the courts have overturned few critical habitat 

decisions on the basis of inadequate science, scientific disagreements over 

these decisions continue.

Purple-spined 

hedgehog cactus

A cactus occurring 

in southwestern 

Utah

Oct. 11, 1979 Nov. 27, 1989 Several reviews after listing discovered that the 

characteristics of the purple-spined hedgehog cactus were 

simply morphological variations within the population of a 

more common species found throughout the Mojave Desert 

in southwestern Utah.

Mexican duck A duck found 

throughout the 

southwestern U.S. 

and Mexico

Mar. 11, 1967 July 25, 1978 After the listing of the Mexican duck, the duck was 

determined to be a subspecies of the common mallard duck 

with a large zone of interbreeding between the two. 

Additional information also indicated that the loss of habitat 

throughout its range was no longer a threat that would 

qualify the species for listing.

(Continued From Previous Page)

Species name Description Date listed Date delisted Reason delisted
Page 28 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Experts and Others Express 

Concerns About Critical Habitat 

Decisions

Experts and others knowledgeable about the Endangered Species Act have 

expressed concerns about the Service’s ability to designate critical habitat 

for some listed species given the amount of information available on the 

species’ habitat needs. Unlike listing decisions, which are more 

straightforward—requiring the Service to answer only a “yes or no” 

question as to whether a species warrants listing—critical habitat decisions 

often require more detailed knowledge about a species’ life history and 

habitat needs and call for the Service to factor in the species’ special 

management needs in addition to the economic impacts of the designation. 

Service officials, experts, and others we spoke to agreed that the amount of 

scientific information available is limited and often affects the Service’s 

ability to adequately define the habitat essential to the species’ 

conservation. While some interested parties stated that the Service 

designated areas too broadly and included lands unsuitable for several 

species, others said that the Service did not designate enough habitat for 

some listed species. According to Service officials, the resource and time 

constraints under which the Service’s scientists work often preclude them 

from collecting new information and, as a result, the information available 

may limit their ability to produce adequate critical habitat designations for 

some species. We found that most scientific disagreements surrounding 

recent critical habitat designations concerned whether the area chosen as 

critical habitat is sufficiently defined or whether the overall information 

used to support the designation is adequate. (See app. IV for information on 

the nature of scientific controversy surrounding the Service’s decisions to 

designate critical habitat for listed species.) In order to increase the 

amount of information available on which to base critical habitat 

designations, the Service and others, including the National Research 

Council, have recommended delaying designations until recovery plans are 

developed.33 

Peer Reviewers Generally 

Support the Service’s Critical 

Habitat Designations, but Raise 

Concerns about the Areas 

Selected 

The Service received 69 peer-review responses for 27 of the 37 critical 

habitat decisions finalized during fiscal years 1999 through 2002; it received 

no responses for 10 decisions (see app. III). Reviewers providing 

comments in 17 of these decisions unanimously agreed with the Service’s 

scientific conclusions or otherwise indicated support for the critical habitat 

designation. In six decisions, while not stating explicit agreement with the 

Service’s use of science, the reviewer did not identify any major 

inadequacies or reasons for substantially modifying the proposed habitat. 

33National Research Council, Science and the Endangered Species Act (Washington D.C.: 

National Academy Press, 1995) 71-93.
Page 29 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

In another decision, the Service reported that five peer reviewers 

supported the decision and one was “neutral.” One or more peer reviewers 

disagreed with the Service’s proposed critical habitat designations for the 

remaining three decisions: 

• Zapata bladderpod. The one reviewer responding to the proposed 

critical habitat designation of the Zapata bladderpod, a flowering plant 

that grows in Texas, stated that the areas selected on state and private 

lands were too small to support viable populations or the area was not 

always suitable habitat for the species. The reviewer also said it was 

premature to select those sites given the lack of information about the 

species.

• Cactus ferruginous pygmy-owl. The one reviewer responding to the 

proposed critical habitat designation for the cactus ferruginous pygmyowl, a small bird found in the southwestern United States, disagreed 

with the designation on the grounds that there were too many 

unknowns about the species’ habitat requirements to support a 

determination about its critical habitat. 

• Newcomb’s snail. Two of the six reviewers responding to the Service’s 

proposed critical habitat determination for the Newcomb’s snail (found 

only on the island of Kauai, Hawaii) disagreed with the proposed rule—

the other four supported it. One of the reviewers who disagreed stated 

that there was inadequate information to make a determination because 

habitat requirements for the snail were limited to generalized 

observations in the field and thus were speculative. The reviewer said 

the designation did not identify the habitat features essential to the 

conservation of the species and was premature until additional 

biological information was obtained. Similarly, the other reviewer 

objecting to the determination did so largely because of his 

understanding that the process was based on few published scientific 

studies, and much was still unknown about the species’ habitat 

requirements. 

Even though peer reviewers may have concurred with the Service’s critical 

habitat designation, many provided clarifications or suggested 

modifications. We analyzed the peer reviewers’ responses for 16 of the 27 

critical habitat decisions the Service made. There were 35 peer-review 

responses to these 16 decisions. Nearly all of the reviewers provided 

specific clarifications on information contained in the rule or suggestions 

for altering the habitat area selected. For instance, in many of the 
Page 30 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

responses, the reviewer agreed with the proposal in general, but stated that 

additional lands should be included in the critical habitat designation and 

cited scientific reasons for increasing habitat areas. In one decision, a 

reviewer generally supporting the proposed critical habitat of the arroyo 

toad (an endangered toad found in coastal and desert drainages in 

California) identified specific areas where he believed the toad ranged 

more widely and would therefore warrant additional critical habitat. 

Another reviewer, generally supporting the proposed critical habitat for the 

Great Lakes population of the piping plover (a small shorebird that occurs 

across North America), identified sites she believed should be added to the 

designation and areas she believed to be unsuitable for the species and 

therefore should be excluded from the designation. 

Courts Have Overturned Few 

Critical Habitat Decisions on the 

Basis of Inadequate Science 

As with listing decisions, and due in part to the deference the courts grant 

to the Service, most litigation has not directly challenged the Service’s use 

of science in making critical habitat determinations. Based on a review of 

federal court cases decided during fiscal years 1999 through 2002, we 

identified 11 cases in which a court issued an opinion regarding the 

Service’s critical habitat decisions. Most of these 11 cases dealt with 

nonscience issues, such as the Service’s failure to designate critical habitat 

for a listed species. However, the courts overturned critical habitat 

decisions on the basis of issues related to the use of scientific data in the 

following two cases:34 

• Rio Grande silvery minnow. In 2000, a federal court invalidated the 

critical habitat of the Rio Grande silvery minnow based in part on 

scientific grounds.35 Multiple groups, including the state of New Mexico, 

challenged the designation of critical habitat for the silvery minnow, a 

fish found exclusively in the Rio Grande River in the Southwest. The 

critical habitat designation for this fish consisted of a 163-mile stretch of 

the main stem of the Rio Grande River. The court ruled in favor of the 

plaintiffs because it found that the Service’s final rule had failed to (1) 

define with sufficient specificity what biological and physical features 

were essential to the species’ survival and recovery and (2) indicate 

34In fiscal year 2003, a court overturned one additional critical habitat decision of the 

Service partly on the basis of issues related to the use of scientific data. See Home Builders 

Association of Northern California v. United States Fish and Wildlife Service, No. CV F 

01-5722 AWI SMS (E.D.Cal. May 9, 2003). 

35Middle Rio Grande Conservancy District v. Babbitt, 206 F.Supp.2d 1156 (D.N.M. 2000), 

aff’d, 294 F.3d 1220 (10th Cir. 2002).
Page 31 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

where in each reach of the river such features existed. For example, the 

court said that the Service’s statement in the rule regarding the 

minnow’s need for “sufficient flowing water” provided vague 

generalities that stated little more than what is required for any fish 

species. As a result of this court ruling, the Service is in the process of 

redesignating critical habitat for this species.

• Cactus ferruginous pygmy-owl. In 2001, a court struck down the 

critical habitat designation for the cactus ferruginous pygmy-owl 

because, among other reasons, the designation was not supported by 

the best available scientific data.36 The final critical habitat for the 

pygmy-owl, a small bird found in the southwestern United States, 

consisted of over 700,000 acres of riparian and upland habitat in 

Arizona. The court noted that the determination of critical habitat is to 

be made on the basis of the “best scientific data available” and that this 

involves identifying geographic areas “essential to the conservation of 

the species.” The court then pointed out that systematic owl surveys 

had not yet been completed over the entire potential habitat in Arizona, 

and that the Service determined critical habitat by designating areas 

where the pygmy-owls had been sighted, areas that it thought would be 

consistent with the species’ known habitat, and all the land in between. 

The court also pointed out that, in addition to the areas actually 

occupied by the pygmy-owls, the Service had included areas where it 

thought they could live. The court appeared to conclude that, in order 

to include areas that were not presently occupied, the Service should 

have determined that such areas were in fact essential to the 

conservation of the species. Although the Service had already agreed to 

reconsider the economic analysis used in the critical habitat 

designation, the court concluded that a “broader reconsideration” of the 

critical habitat designation was necessary. The Service is in the process 

of redesignating critical habitat for the pygmy-owl.

36National Association of Homebuilders v. Norton, 2001 WL 1876349, No. 00-CV-903 (D.Ariz. 

2001).
Page 32 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

The Service Has Failed 

to Address Known 

Problems with the 

Critical Habitat 

Program 

The Service’s critical habitat program currently faces a serious crisis that 

extends well beyond the use of science in making decisions. Litigation now 

dominates the program, leading the Assistant Secretary for Fish and 

Wildlife and Parks in the Department of the Interior to recently declare that 

the system for designating critical habitat is “broken” because it provides 

little conservation benefit while consuming significant resources. 

A key court case in 1997 invalidated the Service’s position on when critical 

habitat should be designated. The Endangered Species Act generally 

requires the Service to designate critical habitat for listed species unless 

the Service determines it is “not prudent,”37 and the Service’s regulations 

spell out that it is not prudent to designate critical habitat if doing so would 

not be “beneficial to the species.”38 As a result, prior to 1997, the Service 

had designated critical habitat for only 113 of the 1,023 domestic species 

that it had listed. The Service reasoned that designating critical habitat did 

not benefit the species because the benefits that critical habitat provided 

duplicated those benefits provided by listing the species.39 The 1997 court 

case invalidated the Service’s reasoning, ruling that the Service’s 

determination that it was not prudent to designate critical habitat for the 

coastal California gnatcatcher, a songbird unique to coastal southern 

California, was not justified.40 One of the reasons that the Service 

concluded that it was not prudent to designate critical habitat was because 

it believed that such a designation would not appreciably benefit the 

3716 U.S.C. §1533(a)(3). 

3850 C.F.R. §424.12(a)(1)(ii). The regulation also provides that it is not prudent when the 

species is threatened by human activity and identification of the habitat can be expected to 

increase the threat.

39The Service’s reasoning is based on its reading of the law, as implemented by its 

regulations. The benefit provided by a critical habitat designation is protection from federal 

agency actions—the act requires federal agencies to consult with the Service to ensure that 

any activities they carry out, fund, or authorize are not likely to result in the “destruction or 

adverse modification” of a critical habitat. 16 U.S.C. §1536(a)(2). The act also requires 

federal agencies to insure that their activities are not likely to “jeopardize the continued 

existence” of a listed species. Id. Service regulations define these two terms somewhat 

similarly. See 50 C.F.R. §402.02. The Service reasons that virtually any federal action that 

would destroy or adversely modify a species’ critical habitat would also jeopardize the 

species’ existence. The Service thus concludes that critical habitat designations do not 

provide additional conservation benefit beyond that already afforded all listed species. 

40Natural Resources Defense Council v. United States Department of the Interior, 113 F.3d 

1121 (9th Cir. 1997). See also Sierra Club v. United States Fish and Wildlife Service, 245 

F.3d 434 (5th Cir. 2001).
Page 33 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

species because most populations of gnatcatchers were found on private 

lands to which the act’s critical habitat protections would not apply. The 

court found that this reasoning improperly expanded what Congress had 

intended to be a narrow exception to designating critical habitat. The court 

concluded that the Service had disregarded “the clear congressional intent 

that the imprudence exception be a rare exception.” Since then, court 

orders and settlement agreements have compelled the Service to designate 

critical habitat for species for which it had previously determined that it 

was not prudent to do so. 

Subsequently, a 2001 court case led the Service to reconsider some of its 

critical habitat designations.41 The case involved the requirement of the act 

that the Service consider the economic impact of designating a particular 

area as critical habitat. According to the act, the Service may exclude areas 

from critical habitat if it determines that the benefits of excluding the area 

outweigh the benefits of including the area as critical habitat unless 

excluding it would result in the extinction of the species. For example, in 

1997, the Service designated critical habitat for the southwestern willow 

flycatcher, a small bird that nests in riparian areas in the southwestern 

United States. Because the Service believed that designating critical 

habitat would not result in additional restrictions on activities beyond 

those resulting from listing the species, it reasoned that there would be no 

significant economic impact associated with designating critical habitat for 

the flycatcher.42 However, the court disagreed. It found that since the act 

clearly barred the Service from considering economic impacts in listing 

decisions, but required they be considered in critical habitat decisions, the 

Service was not free to ignore the economic impacts of listing a species 

when designating critical habitat for that species. The court held that the 

Service had to consider all of the economic impacts of a critical habitat 

determination, regardless of whether those impacts were also attributable 

to listing or other causes. Since this decision was issued, court orders and 

settlement agreements have prompted the Service to re-issue some critical 

habitat decisions to comply with this standard. 

41New Mexico Cattle Growers v. United States Fish and Wildlife Service, 248 F.3d 1277 (10th

Cir. 2001).

42The Service’s approach was premised on the idea that designating critical habitat does not 

provide protection to a species beyond the protection already provided by listing the 

species. See footnote 39. 
Page 34 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Since these two court rulings, the Service’s critical habitat program has 

become dominated by litigation. Each critical habitat designation made 

since 1997 has resulted from a court order or a settlement agreement, and 

the Service expects that it will have to dedicate significant resources 

through fiscal year 2008 to comply with existing court orders and 

settlement agreements. The department believes that this flood of 

litigation over critical habitat designation is preventing the Service from 

taking what it deems to be higher priority activities, such as addressing the 

approximately 250 “candidate” species waiting to go through the listing 

process (listing and critical habitat activities are funded under the same 

line item in the department’s budget). Service officials noted that there are 

other court decisions that may cause additional problems for the program 

in the future. 

The Service has been aware of problems with its critical habitat program 

for a number of years. The Service noted significant problems with its 

critical habitat program in 1997,43 and in 1999 it issued a Federal Register

notice announcing that its system for designating critical habitat was not 

working and soliciting comments on its intention to develop policy or 

guidance and/or to revise regulations or seek legislative corrections to 

clarify the role of critical habitat in conserving endangered species.44 In 

particular, the Service stated its intention to consider when critical habitat 

designation would provide additional protection beyond that provided by 

listing. The Service also announced its intention to streamline the process 

for designating critical habitat to be more cost-effective and in line with the 

amount of conservation benefit provided to the species. In particular, the 

Service declared that it needs to develop a much less labor-intensive 

process for describing the areas proposed for designation as critical 

habitat. The Service also stated that it can streamline and make more costeffective the process to conduct the economic analyses required to 

designate critical habitat and that it can more efficiently conduct the 

analyses required under the National Environmental Policy Act. The 

Service also noted that critical habitat litigation and related court orders 

43In the 1997 final rule designating critical habitat for the southwestern willow flycatcher, 

the Service stated that it was unable to provide the level of analysis and completeness that it 

has in previous rules because of a court imposed deadline—the result of the Service’s 

previous determination that critical habitat provided little additional benefit to the species. 

Even with a minimal level of analysis and completeness, the Service noted that it had to 

disrupt significant work at the field office, regional, and national levels in order to provide 

the resources to complete the rule. See 62 Fed. Reg. 39129 (July 22, 1997). 

44See 64 Fed. Reg. 31871 (June 14, 1999).
Page 35 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

were consuming much of the resources devoted to listing and critical 

habitat, and delaying other activities that it considered higher priority, such 

as addressing petitions submitted by citizens, working with landowners on 

conservation projects, and completing final actions to list species. 

However, no additional guidance or revisions were issued, and the Service 

continues to follow the same unworkable system. 

The Department of the Interior recently echoed concerns with the Service’s 

critical habitat program and the limited conservation benefit it provides to 

species. In April 2003, the Assistant Secretary for Fish and Wildlife and 

Parks testified before Congress on the critical habitat program, stating that 

it is “broken” and in “chaos.” He noted that litigation support is consuming 

valuable resources and that complying with court orders and settlement 

agreements has sharply reduced the Service’s ability to prioritize its listing 

and critical habitat actions. Service scientists working in field offices 

expressed similar concerns to us about the critical habitat program, raising 

questions about the purpose of critical habitat and the designation process. 

An attorney in the Solicitor’s office told us that guidance would improve the 

Service’s critical habitat decisions and make the decisions more defensible 

in court in the future. 

Despite the long-standing concerns over the role and implementation of the 

critical habitat program, the Service has done little to resolve them. In a 

report issued in June 2002, we recognized the impact that litigation was 

having on the critical habitat program and recommended that the Service 

expedite its efforts to develop guidance on designating critical habitat for 

listed species to help reduce the influence of future litigation.45 Better 

guidance would help reduce the number of legal challenges to the Service’s 

critical habitat designations and allow the Service to better withstand legal 

challenges when they arise. While the Service agreed with our 

recommendation, it responded that work on critical habitat guidance had 

been delayed pending Service efforts to complete higher priority tasks, 

including court orders to complete listing and critical habitat decisions and 

did not commit to a schedule for issuing the guidance. An official with 

Interior’s Solicitor’s office told us that one factor limiting the agency’s 

ability to complete these tasks is the Service’s inability to devote significant 

listing and critical habitat resources to policy initiatives without risking 

45U.S. General Accounting Office, Endangered Species Program: Information on How 

Funds Are Allocated and What Activities Are Emphasized, GAO-02-581 (Washington, D.C.: 

June 25, 2002).
Page 36 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

contempt of court because such action would force the agency to divert 

resources away from activities required to comply with court orders. 

Conclusion The Service’s critical habitat program faces a serious crisis because of 

extensive litigation that is consuming significant program resources. The 

Service has recognized this crisis for many years but has done little to 

address it. Accordingly, in June 2002, we recommended that the Service 

expedite its efforts to develop guidance on designating critical habitat to 

reduce the influence of future litigation. While the Service agreed with our 

recommendation, it has done little to develop this guidance. Service 

officials complain that they are locked in a vicious cycle, precluded from 

developing the guidance for fear of being held in contempt of court for 

diverting resources away from activities already required by existing court 

orders. While the Service clearly faces a dilemma, it is imperative that it 

clarify the role of critical habitat and develop guidance for how and when it 

should be designated, and seek regulatory and/or legislative changes that 

may be necessary to provide threatened and endangered species with the 

greatest conservation benefit in the most cost-effective manner.

Recommendation for 

Executive Action

Because the Service’s critical habitat program faces serious challenges, we 

recommend that the Secretary of the Interior require the Service to provide 

clear strategic direction for the critical habitat program, within a specified 

time frame, by clarifying the role of critical habitat and how and when it 

should be designated, and recommending policy/guidance, regulatory, 

and/or legislative changes necessary to provide the greatest conservation 

benefit to threatened and endangered species in the most cost-effective 

manner.

Agency Comments We provided the Department of the Interior with a draft of this report. The 

department did not provide comments on the draft. 

As agreed with your offices, unless you publicly announce the contents of 

this report earlier, we plan no further distribution until 30 days from the 

report date. At that time, we will send copies of this report to the Secretary 

of the Interior and other interested parties. We also will make copies 
Page 37 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

available to others upon request. In addition, the report will be available at 

no charge on the GAO Web site at http://www.gao.gov. 

If you or your staffs have any questions, please call me at (202) 512-3841. 

Key contributors to this report are listed in appendix V.

Barry T. Hill

Director, Natural Resources

 and Environment
Page 38 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Appendix I

Objectives, Scope, and Methodology AAppenednxidexiIs

This report assesses the U.S. Fish and Wildlife Service’s consideration and 

use of science in its decisions to list species as threatened or endangered 

and to designate critical habitat.1

 Specifically, we were asked to review the 

extent to which (1) the Service’s policies and practices ensure that listing 

and critical habitat decisions are based on the best available science and 

(2) outside reviewers have supported the scientific data and conclusions 

that the Service uses to make listing and critical habitat decisions. In no 

instance did we attempt to evaluate scientific data and render an opinion. 

For this evaluation, we define “science” as the collection and interpretation 

of biological information, such as the identification of a species and its 

habitat needs. This definition does not include the legal policies and 

definitions found in the law or used to implement or interpret the 

Endangered Species Act. However, we acknowledge that there is not 

always a clear distinction between the interpretation of biological 

information and the policies and definitions used to interpret the act. 

In meeting our first objective, we examined the Service’s decision-making 

process to determine the extent to which it would likely lead to decisions 

based on the best available science. We reviewed the Service’s policies and 

procedures related to how it makes these decisions and discussed the 

process and procedures with key officials at the Service’s headquarters and 

with staff in the Service’s regional and field offices to determine their 

knowledge of the process and how they implemented it. We also spoke 

with peer-review experts and examined the literature on the processes that 

organizations use to peer review their decisions and products to assess the 

reasonableness of the Service’s policy to peer review proposed listing and 

critical habitat decisions. 

In meeting both objectives, we obtained from the Service a list of the 

decisions to list species and designate critical habitat that the Service 

finalized during fiscal years 1999 through 2002. To verify the completeness 

of the provided list of decisions, we compared it with a second independent 

database maintained by the Service. We identified one decision that was 

not on the original list provided to us by the Service. We included that 

decision in our analysis. Based on this information, we identified 101 final 

1

We focused on the U.S. Fish and Wildlife Service even though it shares responsibility with 

the National Marine Fisheries Service for implementing the Endangered Species Act 

because the Fish and Wildlife Service has lead responsibility, as of April 2003, for 1,237 of 

the 1,263 listed species in the United States. The two Services share responsibility for 6 

species. 
Appendix I

Objectives, Scope, and Methodology

Page 39 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

decisions to list or designate critical habitat that were published in the 

Federal Register during fiscal years 1999 through 2002. 

We examined the Federal Register notices for the 101 decisions to 

determine (1) the extent to which the Service complied with its peer-review 

policy to request at least three peer reviewers to review each decision, (2) 

the number that reviewed each decision, and (3) whether or not the 

reviewer(s) supported the decision. In 61 of the 101 decisions, we 

extracted this information from the Federal Register. For the remaining 40 

decisions, we contacted the 18 field offices responsible for the decisions 

and requested that they provide the peer-review documentation, including 

copies of the peer reviewers’ responses. The Service provided us with the 

missing information in all but seven instances; in five of those instances 

partial information was available. 

To assess the accuracy of the information reported in the Federal Register

notices, we requested that the Service provide documentation for the peerreview information, including peer reviewers’ responses, for 8 of the 61 

decisions for which complete information was available in the Federal 

Register notice. We selected these 8 decisions in the following way. In 

order to minimize the burden on the Service’s field staff, we limited our 

universe to the decisions that were the responsibility of the18 field offices 

that we already intended to contact. These offices were responsible for 48 

of the 61 decisions for which there was complete information in the 

Federal Register notice. We then randomly chose 1 decision from each of 

the three offices with the most decisions. Collectively these offices were 

responsible for 25 of the 48 decisions. We also randomly chose 5 of the 

remaining 23 decisions. We compared the documentation provided to us 

with the information in the corresponding Federal Register notices. We 

found no discrepancies. However, we did find minor discrepancies 

between other Federal Register notices and the documentation the Service 

provided to us. We reconciled these discrepancies. Additionally, based on a 

limited review, we found the Service’s procedures reasonable for ensuring 

that its database contains accurate information. For example, the Service 

regularly samples data recently added to the database for accuracy. We did 

not determine the extent to which any of the Service’s final decisions 

reflected the comments and opinions of the peer reviewers. 

In addition to determining whether peer reviewers supported the decision 

they reviewed, we performed a content analysis on the peer-review 

responses for 16 critical habitat decisions to more fully characterize the 

opinions of the peer reviewers. We chose to perform a content analysis on 
Appendix I

Objectives, Scope, and Methodology

Page 40 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

the responses to critical habitat decisions because these decisions are 

open-ended, requiring the Service to determine how much critical habitat 

to designate and where that habitat should be located. There were 35 peerreview responses for these 16 decisions. 

To determine how well the Service’s listing and critical habitat decisions 

are withstanding legal challenges to the science supporting those 

decisions, we used common legal research methods to identify federal 

court cases related to the Service’s listing and critical habitat decisions. We 

identified and reviewed 25 cases that were decided during fiscal years 1999 

through 2002 that involved a challenge to a Service listing decision and/or 

critical habitat decision, and in which the court rendered a decision on the 

listing or critical habitat issue. 

To determine the extent to which the Service has delisted species because 

new scientific information surfaced indicating that listing was not 

originally warranted, we used information from the Service’s publicly 

accessible database. We included in our analysis all decisions to delist 

species from the inception of the act through March 2003. We compared 

this information with information published in the Federal Register. We 

found no discrepancies. 

Finally, to get a fuller understanding of the degree of scientific controversy 

regarding listing and critical habitat decisions, we solicited the opinions of 

experts and others and reviewed published studies. To illustrate the nature 

of scientific controversy regarding listing and critical habitat decisions, we 

developed a list of decisions for which there was some degree of scientific 

controversy. We developed this list by asking experts in the private, 

academic, government, and nonprofit sectors spanning the political 

spectrum to identify recent decisions that were particularly controversial 

due to scientific disagreements and briefly explain the nature of the 

controversy. We limited our analysis to decisions finalized during fiscal 

years 1993 through 2002. In addition, we asked each expert for the names 

of other experts who could help us develop our list. We stopped contacting 

experts when we began to get repetitive responses. We then identified 

common issues related to the controversies to characterize the types of 

disagreements involved with each of the decisions. We based this on the 

information provided by the experts and information published in the 

Federal Register. Finally, we presented the list of decisions and related 

information to officials at the Service and at the National Academy of 

Sciences for their opinions on the list of decisions and how we 
Appendix I

Objectives, Scope, and Methodology

Page 41 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

characterized them. The officials generally agreed with the information we 

presented. 

Additionally, in the course of our work, it became apparent that litigation 

was dominating the Service’s critical habitat program, and we discuss these 

circumstances in our report. Specifically, we describe how several key 

court cases are affecting the program. 

We performed our work from September 2002 through June 2003 in 

accordance with generally accepted government auditing standards.
Page 42 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Appendix II

Overview of The Endangered Species Act ApendxiI

The Endangered Species Act was passed by Congress to provide a means to 

conserve the ecosystems upon which endangered and threatened species 

depend and to conserve and recover imperiled species. The act was passed 

in 1973 and replaced earlier laws, which provided for a list of endangered 

species but gave them little meaningful protection. While significant 

amendments were enacted in 1978, 1982, and 1988, the overall framework 

of the act has remained essentially unchanged. The Department of the 

Interior delegated its responsibility for the act to the U.S. Fish and Wildlife 

Service (Service), which established an endangered species program to 

implement the requirements of the act. The Service is responsible for all 

land-dwelling species, freshwater species, some marine mammals, and 

migratory birds. The Department of Commerce, which has delegated its 

responsibility to the National Marine Fisheries Service, is responsible for 

implementing the act for marine species including anadromous (both 

freshwater and ocean dwelling) fish. 

The act provides numerous provisions to protect and recover species at 

risk of extinction. However, before a plant or animal species is eligible to 

benefit from most of these provisions, it must first be added to the Federal 

List of Endangered and Threatened Wildlife and Plants. Once on the list, 

key provisions of the act, including critical habitat, recovery plans, 

consultations with federal agencies, and habitat conservation plans, are 

designed to assist in recovering the species so that it can then be removed 

from the list. 
Appendix II

Overview of The Endangered Species Act

Page 43 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Listing Species as 

Endangered or 

Threatened 

Under the act, species may be listed as either endangered or threatened. 

An endangered species is any species of animal or plant that is in danger of 

extinction throughout all or a significant portion of its range. A threatened 

species is any species of animal or plant that is likely to become 

endangered within the foreseeable future throughout all or a significant 

portion of its range. All species of plants and animals (except pest insects) 

are eligible for listing as endangered or threatened. As of June 2003, there 

were a total of 1,821 listed species; 1,504 species on the endangered species 

list, 987 of which occur in the United States; and 317 threatened species, 

276 of which occur in the United States.1

 

The decision to list a species must be based solely on the best available 

scientific and commercial data. Using these data, the Service must 

determine whether a species should be listed by analyzing its status based 

on the following factors: (1) current or threatened destruction, 

modification, or curtailment of a species habitat or range; (2) over 

utilization of the species for commercial, recreational, scientific, or 

educational purposes; (3) disease or predation; (4) inadequacy of existing 

regulatory mechanisms; and (5) other natural or manmade factors affecting 

the species’ continued existence. The Service follows a rigorous process to 

determine whether to list a species. A final decision to list a species is 

published in the Federal Register. 

The Service may issue emergency regulations to list a species without 

complying with the normal regulatory process if it finds that an emergency 

poses a significant risk to the well-being of any species. Emergency 

regulations take effect immediately upon publication in the Federal 

Register and are effective for 240 days. 

The Service also maintains a list of candidate species. Candidate species 

are species for which substantial information is available to support a 

listing proposal, but have not yet been proposed for listing. The Service 

maintains this list for a variety of reasons, including (1) to provide advance 

knowledge of potential listings that could affect decisions of environmental 

1

The List of Endangered and Threatened Wildlife and Plants created under the act identifies 

listed species as either domestic or foreign. The Service’s Endangered Species Program 

deals primarily with domestic species found in the U.S. and U.S. territories, while the 

International Affairs Program of the Service deals primarily with foreign endangered 

species—including issuing permits for their import or export and representing the Service 

under the Convention on International Trade in Endangered Species (CITES). 
Appendix II

Overview of The Endangered Species Act

Page 44 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

planners and developers, (2) to solicit input from interested parties to 

identify those candidate species that may not require protection under the 

act or additional species that may require the act’s protections, and (3) to 

solicit information needed to prioritize the order in which species will be 

proposed for listing. The Service is required to publish a notice of review 

annually in the Federal Register to solicit new information on the status of 

candidate species. The Service works with parties, such as states and 

private partners, to carry out conservation actions—often called Candidate 

Conservation Agreements—for candidate species to prevent their further 

decline and possibly eliminate the need to list them as endangered or 

threatened. As of June 2003, there were 251 candidate species, many of 

which have held that status for more than a decade. 

Critical Habitat The Service is generally required to designate critical habitat at the time a 

species is listed as endangered or threatened. Critical habitat is the 

specific geographic area essential for the conservation of a threatened or 

endangered species and that may require special management 

considerations and protection. Critical habitat contains physical and 

biological habitat features such as: (1) space for individual and population 

growth and for normal behavior; (2) cover or shelter, food, water, air, light, 

minerals, or other nutritional or physiological requirements; (3) sites for 

breeding and rearing offspring; and (4) habitats that are protected from 

disturbances or are representative of the historic geographical and 

ecological distributions of a species. Critical habitat may also include 

areas not occupied by the species at the time of listing but that are essential 

to the conservation and recovery of the species. Unlike the decision to list 

a species as endangered or threatened, a final designation of critical habitat 

is to be made on the basis of not only the best scientific data available but 

also taking into consideration the economic and other effects of making the 

decision. If the benefits of excluding an area outweigh the benefits of 

including it, the Service may exclude an area from critical habitat, unless 

the exclusion would result in the extinction of the species. 

The Service may take up to an additional year after listing a species to 

designate critical habitat if it finds that critical habitat is “not 

determinable.” Critical habitat is not determinable when information 

sufficient to perform the required analyses of the impacts of the 

designation of critical habitat is lacking or the biological needs of the 

species are not sufficiently known to permit identification of an area as 

critical habitat. The Service does not designate critical habitat if it 

determines that doing so would be “not prudent.” It would not be prudent 
Appendix II

Overview of The Endangered Species Act

Page 45 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

to designate critical habitat if (1) identifying the habitat is expected to 

increase the threat to the species or (2) designating an area as critical 

habitat is not expected to benefit the species. 

Recovery Plans Once a species is listed, the act requires the Service to develop a recovery 

plan for the species. Recovery plans identify, justify, and schedule the 

research and management actions necessary to reverse the decline of a 

species and ensure its long-term survival. Recovery plans must be 

developed for all listed species, unless such a plan would not benefit the 

species. Although the act does not specify time frames for developing or 

implementing the recovery plan or for recovering the species, the Service 

has as a goal of developing recovery plans within 1 year and having 

approved plans within 21⁄2 years of a species’ listing. The Service solicits 

comments from state and federal agencies, experts and the public on draft 

recovery plans during a formal public comment period announced in the 

Federal Register. The Service periodically reviews approved recovery 

plans to determine if updates or revisions are needed. As of June 2003, 

1000 species had approved recovery plans.

Consultations with 

Federal Agencies

Federal agencies are required to consult with the Service if their actions 

may affect listed species. The goal of the consultation process is to identify 

and resolve conflicts between the protection and enhancement of listed 

species and proposed federal actions. The act requires that all federal 

agencies consult with the Service to ensure that any activities agencies 

permit, fund, or conduct are not likely to jeopardize the continued 

existence of a listed species or adversely modify its critical habitat. 

Federal agencies may informally consult with the Service to determine 

whether their actions may affect listed species and must proceed to formal 

consultations once they determine that their actions may adversely affect a 

listed species or its habitat. The act requires a formal consultation to be 

completed in 90 days, unless the Service and the federal agency mutually 

agree to an extension, with the applicant’s consent. The Service is to issue 

a “biological opinion” within 45 days of the conclusion of formal 

consultation that reviews the potential effects of the proposed action on 

listed species and/or critical habitat. The Service must base the biological 

opinion on the best available biological information. If the Service finds 

that the action would appreciably reduce the likelihood of the species’ 

survival and recovery, it issues a jeopardy biological opinion. Jeopardy 

opinions include reasonable and prudent alternatives that define 
Appendix II

Overview of The Endangered Species Act

Page 46 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

modifications to the agency’s proposed action that enable it to continue 

and still be consistent with the act’s requirements for protecting species. 

Following the issuance of the biological opinion, the federal agency 

determines whether it will comply with the opinion or seek an exemption 

from the act’s requirements. 

Proposed federal agency actions that have been determined to cause 

jeopardy to any listed species may receive an exemption from the act by 

the Federal Endangered Species Committee (also referred to as the “God 

Squad”). The Endangered Species Committee is comprised of seven 

members: the Secretary of Agriculture, the Secretary of the Army, 

Chairman of the Council of Economic Advisors, the Administrator of the 

Environmental Protection Agency, the Secretary of the Interior, the 

Administrator of the National Oceanic and Atmospheric Administration, 

and one individual from the affected state. An exemption is granted if at 

least five members of the Endangered Species Committee determine that, 

among other things, the action is of regional or national significance, that 

the benefits of the action clearly outweigh the benefits of conserving the 

species, and that there are no reasonable and prudent alternatives to the 

action. The Endangered Species Committee has been convened only three 

times since its creation in 1978—the Tellico Dam for the snail darter fish in 

Tennessee, the Grayrocks Dam in Wyoming for the whooping crane, and 

Bureau of Land Management (BLM) timber sales for the spotted owl in 

Oregon. Only two exemptions were granted. One was in regard to the 

Grayrocks dam and the other was to approve 13 timber sales sought by 

BLM (which was withdrawn before the completion of appeals). The Tellico 

dam application was denied but was later allowed by Congress to proceed.2

 

In addition, three other applications were received but were subsequently 

dismissed or withdrawn before deliberations took place.

2

Energy and Water Development Appropriations Act of 1980, Pub. L. No. 96-69, 93 Stat. 437, 

449 (1979).
Appendix II

Overview of The Endangered Species Act

Page 47 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Habitat Conservation 

Plans

The act generally prohibits any person from “taking” an animal species 

listed as endangered.3

 “Taking” or “take” means to harass, harm, pursue, 

hunt, shoot, wound, kill, trap, capture or collect a listed species, and under 

Service guidelines, includes the destruction of the species’ habitat. 

However, in 1982, Congress amended the act to include a process whereby 

the Service may issue permits that allow private individuals to incidentally 

take listed species. Incidental take is the take of any federally listed 

species that is incidental to, but not the purpose of, otherwise lawful 

activities. Permit applicants are required to submit a habitat conservation 

plan, which includes measures the applicant will take to minimize and 

mitigate the impacts that may result from the taking. The Service is 

required to publish a notice in the Federal Register soliciting comments 

from interested parties on each application for a permit and its 

accompanying habitat conservation plan. As of April 2003, 416 habitat 

conservation plans have been approved. The act prohibits the Service from 

issuing a permit if doing so would appreciably reduce the likelihood of the 

survival and recovery of the species in the wild. The incidental taking of a 

listed species resulting from federal agency actions may also be allowed 

under the act and would be addressed through the consultation process. 

3

16 U.S.C. §1538(a)(1)(B), (C). The Endangered Species Act prohibits the taking of 

endangered, but not threatened, species. However, the act authorizes the Service to, by 

regulation, prohibit the taking of a threatened species. The Service has issued a regulation 

extending the take prohibitions to threatened species, except for those covered by a specific 

rule, exemption, or permit. 50 C.F.R. §17.31. 
Page 48 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Appendix III

Peer Reviewers’ Responses to Listing and 

Critical Habitat Decisions for Fiscal Years 

1999 through 2002 ApendxiI

Federal Register title and 

number Date

Peer reviewers Peer reviewers’ response

Asked Responded Agree Disagree Neutral

Unknown/ 

unclear

Listing decisions

Determination of Endangered 

or Threatened Status for Five 

Desert Milk-vetch Taxa From 

California (63 FR 53596)

Oct. 6,

1998

32 2

Determination of Endangered or 

Threatened Status for Four 

Southwestern California Plants 

from Vernal Wetlands and Clay 

Soils (63 FR 54975)

Oct. 13, 

1998

31 1

Determinations of Endangered 

or Threatened Status for Four 

Plants (63 FR 54938)

Oct. 13, 

1998

32 2

Endangered or Threatened 

Status for Three Plants from 

the Chaparral and Scrub of 

Southwestern California 

(63 FR 54956)

Oct. 13, 

1998

3 0

Endangered Status for Three 

Aquatic Snails, and Threatened 

Status for Three Aquatic Snails 

in the Mobile River Basin of 

Alabama (63 FR 57610)

Oct. 28, 

1998

41 1

Determination of Threatened 

Status for Virginia Sneezweed 

(Helenium virginicum) a Plant 

From the Shenandoah Valley of 

Virginia (63 FR 59239)

Nov. 3, 

1998

32 2

Final Rule to List the 

Arkansas River Basin 

Population of the Arkansas River 

Shiner (Notropis girardi) as 

Threatened (63 FR 64772)

Nov. 23, 

1998

20 1 1

Final Rule To List the 

Topeka Shiner as Endangered 

(63 FR 69008)

Dec. 15, 

1998

31 1

Determination of Endangered 

Status for the St. Andrew Beach 

Mouse (63 FR 70053)

Dec. 18, 

1998

44 4

Determination of Threatened 

Status for the Sacramento 

Splittail (64 FR 5963)

Feb. 8, 

1999

3 0
Appendix III

Peer Reviewers’ Responses to Listing and 

Critical Habitat Decisions for Fiscal Years 

1999 through 2002

Page 49 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Determination of Endangered 

Status for Catesbaea 

Melanocarpa (64 FR 13116)

Mar 17, 

1999

4 0

Final Rule To List the Flatwoods 

Salamander as a Threatened 

Species (64 FR 15691)

Apr. 1, 

1999

43 3

Threatened Status for the 

Plant Thelypodium howellii 

ssp. spectabilis (Howell’s 

spectacular thelypody) 

(64 FR 28393)

May 26, 

1999

32 2

Determination of Endangered 

Status for the Plant Eriogonum 

apricum (inclusive of vars. 

apricum and prostratum) (Ione 

Buckwheat) and Threatened 

Status for the Plant 

Arctostaphylos myrtifolia (64 FR 

28403)

May 26, 

1999

31 1

Threatened Status for Lake Erie 

Water Snakes (Nerodia sipedon 

insularum) on the Offshore 

Islands of Western Lake Erie (64 

FR 47126)

Aug. 30, 

1999

a

Final Endangered Status for 

10 Plant Taxa From Maui Nui, HI 

(64 FR 48307)

Sep. 3, 

1999

6 0

Final Rule to List the Devils 

River Minnow as Threatened (64 

FR 56596)

Oct. 20, 

1999

54 4

Final Rule to List Astragalus 

desereticus (Desert milk-vetch) 

as Threatened (64 FR 56590)

Oct. 20, 

1999

33 3

Determination of Threatened 

Status for the Plant Helianthus 

paradoxicus (Pecos Sunflower) 

(64 FR 56582)

Oct. 20, 

1999

32 2

Determination of Threatened 

Status for Bull Trout in the 

Coterminous United States 

(64 FR 58910)

Nov. 1, 

1999

61 1

(Continued From Previous Page)

Federal Register title and 

number Date

Peer reviewers Peer reviewers’ response

Asked Responded Agree Disagree Neutral

Unknown/ 

unclear
Appendix III

Peer Reviewers’ Responses to Listing and 

Critical Habitat Decisions for Fiscal Years 

1999 through 2002

Page 50 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Determination of Endangered 

Status for the Plant 

Lesquerella thamnophila

(Zapata Bladderpod) 

(64 FR 63745)

Nov. 22, 

1999

29 3 3

Final Endangered Status for the 

Plant Fritillaria 

gentneri (Gentner’s fritillary) 

(64 FR 69195)

Dec. 10, 

1999

b 4 4

Determination of Endangered 

Status for Sidalcea oregana var. 

calva (Wenatchee Mountains 

Checker-Mallow) (64 FR 71680)

Dec. 22, 

1999

33 3c

Final Rule To List the Sierra 

Nevada Distinct Population 

Segment of the California 

Bighorn Sheep as Endangered 

(65 FR 20)

Jan. 3, 

2000

33 3

Final Rule To List Two Cave 

Animals From Kauai, Hawaii, as 

Endangered (65 FR 2348)

Jan. 14, 

2000

31 1

Endangered Status for Erigeron 

decumbens var. decumbens

(Willamette Daisy) and Fender’s 

Blue Butterfly (Icaricia icarioides 

fenderi) and Threatened Status 

for Lupinus sulphureus ssp. 

Kincaidii (65 FR 3875)

Jan. 25, 

2000

b 6 6

Endangered Status for the Plant 

Plagiobothrys hirtus (Rough 

Popcornflower) (65 FR 3866)

Jan. 25, 

2000 b 2 2

Determination of Endangered 

Status for Two Larkspurs From 

Coastal Northern California 

(65 FR 4156)

Jan. 26, 

2000

33 3

Determination of Threatened 

Status for Newcomb’s Snail 

From the Hawaiian Islands 

(65 FR 4162)

Jan. 26, 

2000

33 3

Determination of Endangered 

Status for Blackburn’s Sphinx 

Moth from the Hawaiian Islands 

(65 FR 4770)

Feb. 1, 

2000

3 0

(Continued From Previous Page)

Federal Register title and 

number Date

Peer reviewers Peer reviewers’ response

Asked Responded Agree Disagree Neutral

Unknown/ 

unclear
Appendix III

Peer Reviewers’ Responses to Listing and 

Critical Habitat Decisions for Fiscal Years 

1999 through 2002

Page 51 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Determination of Endangered 

Status for the Plant Yreka Phlox 

from Siskiyou County, CA (65 

FR 5268)

Feb. 3, 

2000

31 1

Determination of Endangered 

Status for the Plant Thlaspi 

californicum (Kneel and 

Prairie Penny-Cress) From 

Coastal Northern California 

(65 FR 6332)

Feb. 9, 

2000

3 0

Determination of Endangered 

Status for Sidalcea keckii

(Keck’s checker-mallow) 

From Fresno and Tulare 

Counties, CA (65 FR 7757)

Feb. 16, 

2000

32 2

Final Rule to List the Riparian 

Brush Rabbit and the 

Riparian, or San Joaquin Valley, 

Woodrat as Endangered (65 FR 

8881)

Feb. 23, 

2000

42 2

Endangered Status for the 

Armored Snail and Slender 

Campeloma (65 FR 10033)

Feb. 25, 

2000

2 0

Threatened Status for 

Holocarpha macradenia (Santa 

Cruz tarplant) (65 FR 14898)

Mar. 20, 

2000

44 3 1

Determination of Threatened 

Status for Chlorogalum 

purpureum (Purple Amole), 

a Plant From the South 

Coast Ranges of California 

(65 FR 14878)

Mar. 20, 

2000

32 2

Final Rule for Endangered 

Status for Four Plants From 

South Central Coastal California 

(65 FR 14888)

Mar. 20, 

2000

32 2

Determination of Threatened 

Status for the Contiguous 

U.S. Distinct Population 

Segment of the Canada Lynx 

(65 FR 16052)

Mar. 24, 

2000

62 2

Determination of Threatened 

Status for the Northern Idaho 

Ground Squirrel (65 FR 17779)

Apr. 5, 

2000

11 1b

(Continued From Previous Page)

Federal Register title and 

number Date

Peer reviewers Peer reviewers’ response

Asked Responded Agree Disagree Neutral

Unknown/ 

unclear
Appendix III

Peer Reviewers’ Responses to Listing and 

Critical Habitat Decisions for Fiscal Years 

1999 through 2002

Page 52 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Threatened Status for the Santa 

Ana Sucker (65 FR 19686)

Apr. 12, 

2000 4 2 2

Final Rule To List as 

Endangered the O’ahu ‘Elepaio 

From the Hawaiian Islands and 

Determination of Whether 

Designation of Critical Habitat Is 

Prudent (65 FR 20760)

Apr. 18, 

2000

42 2

Final Rule To List the Alabama 

Sturgeon as Endangered (65 FR 

26438)

May 5, 

2000

5 5 41

Final Rule To List the 

Short-Tailed Albatross 

as Endangered in the 

United States (65 FR 46643)

Jul. 31, 

2000

53 3

Final Rule To List the Santa 

Barbara County Distinct 

Population of the California Tiger 

Salamander as Endangered (65 

FR 57242)

Sep. 21, 

2000

86 6

Endangered and Threatened 

Wildlife and Plants: 

Threatened Status for the 

Colorado Butterfly Plant 

(Gaura neomexicana 

ssp. coloradensis) From 

Southeastern Wyoming, 

Northcentral Colorado, and 

Extreme Western Nebraska (65 

FR 62302)

Oct. 18, 

2000

32 2

Final Endangered Status for a 

Distinct Population Segment of 

Anadromous Atlantic Salmon 

(Salmo salar) in the Gulf of 

Maine (65 FR 69459)

Nov. 17, 

2000

63 3

Final Rule to List Nine Bexar 

County, Texas Invertebrate 

Species as Endangered 

(65 FR 81419)

Dec. 26, 

2000

9 0

Final Rule for Endangered 

Status for Astragalus 

pycnostachyus var. lan 

osissimus (Ventura marsh 

milk-vetch) (66 FR 27901)

May 21, 

2001

31 1

(Continued From Previous Page)

Federal Register title and 

number Date

Peer reviewers Peer reviewers’ response

Asked Responded Agree Disagree Neutral

Unknown/ 

unclear
Appendix III

Peer Reviewers’ Responses to Listing and 

Critical Habitat Decisions for Fiscal Years 

1999 through 2002

Page 53 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Determination of Endangered 

status for Astragalus 

holmgreniorum (Holmgren 

milk-vetch) and Astragalus 

ampullarioides (Shivwits 

milk-vetch) (66 FR 49560)

Sep. 28, 

2001

43 3

Endangered Status for the 

Ohlone Tiger Beetle (Cicindela 

ohlone) (66 FR 50340)

Oct. 3, 

2001

33 3

Determination of Endangered 

Status for the Scaleshell Mussel 

(66 FR 51322)

Oct. 9, 

2001

42 2

Final Rule To List Silene 

spaldingii (Spalding’s Catchfly) 

as Threatened (66 FR 51597)

Oct. 10, 

2001

33 3

Final Rule To List the 

Vermilion Darter as Endangered 

(66 FR 59367)

Nov. 28, 

2001

33 3

Final Rule To List the Mississippi 

Gopher Frog Distinct Population 

Segment of Dusky Gopher Frog 

as Endangered (66 FR 62993)

Dec. 4, 

2001

33 3

Endangered Status for 

Carex lutea (Golden Sedge) (67 

FR 3120)

Jan. 23, 

2002

5 0

Determination of Endangered 

Status for the Washington Plant 

Hackelia venusta (Showy 

Stickseed) (67 FR 5515)

Feb. 6, 

2002

33 3

Endangered Status for the 

Buena Vista Lake Shrew (Sorex 

Ornatus Relictus) (67 FR 10101)

Mar. 6, 

2002

54 3 1b

Listing the Desert Yellowhead as 

Threatened (67 FR 11442)

Mar. 14, 

2002 3 2 1 1

Listing of the Chiricahua 

Leopard Frog (Rana 

chiricahuensis) (67 FR 40789)

Jun. 13, 

2002

44 4

Determination of Endangered 

Status for the Southern 

California Distinct Vertebrate 

Population Segment of the 

Mountain Yellow-legged 

Frog (Rana muscosa) 

(67 FR 44382)

Jul. 2, 

2002

66 6

(Continued From Previous Page)

Federal Register title and 

number Date

Peer reviewers Peer reviewers’ response

Asked Responded Agree Disagree Neutral

Unknown/ 

unclear
Appendix III

Peer Reviewers’ Responses to Listing and 

Critical Habitat Decisions for Fiscal Years 

1999 through 2002

Page 54 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Determination of Endangered 

Status for Ambrosia pumila (San 

Diego Ambrosia) from Southern 

California (67 FR 44372)

Jul. 2, 

2002

31 1

Determination of 

Endangered Status for the 

Carson Wandering Skipper 

(67 FR 51116)

Aug. 7, 

2002

43 2 1

Determination of Endangered 

Status for the Tumbling Creek 

Cavesnail (67 FR 52879)

Aug. 14, 

2002

55 5

Critical habitat decisions

Final Designation of Critical 

Habitat for the Rio Grande 

Silvery Minnow (64 FR 36274)

Jul. 6, 

1999

41 1

Designation of Critical 

Habitat for the Cactus 

Ferruginous Pygmy-owl 

(Glaucidium brasilianum 

cactorum) (64 FR 37419)

Jul. 12, 

1999

41 1

Designation of Critical Habitat 

for the Huachuca Water Umbel 

(64 FR 37441)

Jul. 12, 

1999

31 1

Designation of Critical Habitat 

for the Pacific Coast Population 

of the Western Snowy Plover 

(64 FR 68507)

Dec. 7, 

1999

b

Designation of Critical Habitat 

for the Woundfin and Virgin 

River Chub (65 FR 4140)

Jan. 26, 

2000

0 0

Final Designation of Critical 

Habitat for the Spikedace 

and the Loach Minnow 

(65 FR 24328)

Apr. 25, 

2000

42 2

Final Determination of 

Critical Habitat for the 

Alameda Whipsnake 

(Masticop his lateralis 

euryxanthus) (65 FR 58933)

Oct. 3, 

2000

b

Final Determination of Critical 

Habitat for the San Diego Fairy 

Shrimp (Branchinecta 

sandiegoensis) (65 FR 63438)

Oct. 23, 

2000

42 2

(Continued From Previous Page)

Federal Register title and 

number Date

Peer reviewers Peer reviewers’ response

Asked Responded Agree Disagree Neutral

Unknown/ 

unclear
Appendix III

Peer Reviewers’ Responses to Listing and 

Critical Habitat Decisions for Fiscal Years 

1999 through 2002

Page 55 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Final Determination of 

Critical Habitat for the 

Coastal California Gnatcatcher 

(65 FR 63680)

Oct. 24, 

2000

4 0

Designation of Critical Habit 

at for the Tidewater Goby 

(65 FR 69693)

Nov. 20, 

2000

42 1 1

Final Designation of 

Critical Habitat for the 

Plant Lesquerella 

Thamnophila (Zapata 

Bladderpod) (65 FR 81182)

Dec. 22, 

2000

41 1

Final Designation of Critical 

Habitat for the Mexican Spotted 

Owl (66 FR 8530)

Feb. 1, 

2001

72 2

Final Determination of Critical 

Habitat for Peninsular Bighorn 

Sheep (66 FR 8650)

Feb. 1, 

2001

4 0

Final Determination of Critical 

Habitat for the Alaska-Breeding 

Population of Steller’s Eider 

(66 FR 8850)

Feb. 2, 

2001

52 2

Final Determination of Critical 

Habitat for the Spectacled Eider 

(66 FR 9146)

Feb. 6, 

2001

33 2 1

Final Designation of Critical 

Habitat for the Arroyo Toad 

(66 FR 9414)

Feb. 7, 

2001

52 2

Final Determination of 

Critical Habitat for the Zayante 

Band-Winged Grasshopper 

(66 FR 9219)

Feb. 7, 

2001

32 2

Final Determination of 

Critical Habitat for the 

Morro Shoulderband Snail 

(66 FR 9233)

Feb. 7, 

2000

32 1 1

Final Determinations of Critical 

Habitat for the California Redlegged Frog (66 FR 14626)

Mar. 13, 

2001

52 2

Final Designation of Critical 

Habitat for the Arkansas 

River Basin Population of 

the Arkansas River Shiner 

(66 FR 18002)

Apr. 4, 

2001

9 0

(Continued From Previous Page)

Federal Register title and 

number Date

Peer reviewers Peer reviewers’ response

Asked Responded Agree Disagree Neutral

Unknown/ 

unclear
Appendix III

Peer Reviewers’ Responses to Listing and 

Critical Habitat Decisions for Fiscal Years 

1999 through 2002

Page 56 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Final Determination of 

Critical Habitat for the Bay 

Checkerspot Butterfly 

(Euphydryas editha bayensis) 

(66 FR 21450)

Apr. 30, 

2001

43 3

Final Determination of Critical 

Habitat for the Great Lakes 

Breeding Population of the 

Piping Plover (66 FR 22938)

May 7,

2001

33 2 1

Final Designation of Critical 

Habitat for the Riverside Fairy 

Shrimp (66 FR 29384)

May 30, 

2001

42 1 1

Designation of Critical Habitat 

for the Spruce-fir Moss Spider 

(66 FR 35547)

Jul. 6, 

2001

4 0

Final Determination of Critical 

Habitat for Wintering Piping 

Plovers (66 FR 36138)

Jul. 10, 

2001

53 3

Final Designation of Critical 

Habitat for Sidalcea oregana 

var. calva (Wenatchee 

Mountains checker-mallow) 

(66 FR 46536)

Sep. 6, 

2001

31 1

Final Designation of Critical 

Habitat for the Kootenai River 

Population of the White 

Sturgeon (66 FR 46548)

Sep. 6, 

2001

42 2

Determination of Critical Habitat 

for the Oahu Elepaio 

(Chasiempis san dwichensis 

ibidis) (66 FR 63752)

Dec. 10, 

2001

33 3

Designation of Critical Habitat 

for the Quino Checkerspot 

Butterfly (Euphydryas editha 

quino) (67 FR 18356)

Apr. 15, 

2002

5 0

Final Designation of Critical 

Habitat for the San Bernardino 

Kangaroo Rat (67 FR 19812)

Apr. 23, 

2002

96 5 1

Critical Habitat Designation 

for Chorizanthe robusta var. 

robusta (Robust Spineflower) 

(67 FR 36822)

May 28, 

2002

33 3

(Continued From Previous Page)

Federal Register title and 

number Date

Peer reviewers Peer reviewers’ response

Asked Responded Agree Disagree Neutral

Unknown/ 

unclear
Appendix III

Peer Reviewers’ Responses to Listing and 

Critical Habitat Decisions for Fiscal Years 

1999 through 2002

Page 57 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Source: GAO analysis of U.S. Fish and Wildlife Service data.

a

The Service’s peer review policy does not apply to this decision because its most recent comment 

period opened before the policy became effective.

b

Documentation unavailable.

c

In one instance, the peer reviewer did not explicitly state agreement with the decision, but his 

comments do not bring up anything to suggest disagreement; rather, he provided only minor 

clarifications to the proposed decision document.

Designation of Critical Habitat 

for Chorizanthe pungens var. 

pungens (Monterey Spineflower) 

(67 FR 37498)

May 29, 

2002

44 4

Critical Habitat Designation 

for Chorizanthe robusta var. 

hartwegii (Scotts Valley 

Spineflower) (67 FR 37336)

May 29, 

2002

33 3

Designation of Critical Habitat 

for the Carolina Heelsplitter 

(67 FR 44502)

Jul. 2, 

2002

3 0

Designation of Critical 

Habitat for Newcomb’s Snail (67 

FR 54026)

Aug. 20, 

2002

6 6 42

Designation of Critical Habit at 

for the Northern Great Plains 

Breeding Population of the 

Piping Plover (67 FR 57638)

Sep. 11, 

2002

95 5

Appalachian elktoe final critical 

habitat (67 FR 61016)

Sep. 27, 

2002 4 0

(Continued From Previous Page)

Federal Register title and 

number Date

Peer reviewers Peer reviewers’ response

Asked Responded Agree Disagree Neutral

Unknown/ 

unclear
Page 58 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Appendix IV

The Nature of Scientific Controversy 

Surrounding Listing and Critical Habitat 

Decisions ApendxiIV

Based on discussions with Service officials, experts, and others 

knowledgeable about the Endangered Species Act, we found that several 

scientific disagreements over Service listing decisions have surfaced in 

recent years—mostly concerning whether the amount of information 

available at the time a decision is made suffices as a basis for a decision. 

Regarding critical habitat decisions, we found there has been scientific 

controversy surrounding whether the areas chosen as critical habitat is 

sufficiently defined or the overall information used to support the 

designation is adequate. 

Listing Although we found that scientific disagreements surrounding listing 

decisions are not widespread, some of the controversy in recent years can 

be categorized as “science-related.” Experts and others working with the 

Endangered Species Act that we spoke with identified 11 species where 

there was significant scientific controversy surrounding the decisions to 

list the species.1

 Our discussions with these individuals and a review of 

related Federal Register notices revealed that the most common scientific 

disagreements hinge on whether enough information was available to 

determine (1) whether the plants or animals under consideration qualified 

as a “species” as defined by the act, (2) the status of the species, or (3) the 

degree of threat that the species faces. 

Critics of some listing decisions argued that the Service lacked information 

to determine whether the entity in question met the definition of a 

“species.” The act defines a species as including “any subspecies of fish or 

wildlife or plants, and any distinct population segment of any species of 

vertebrate fish or wildlife which interbreeds when mature.”2

 There is 

general agreement within the scientific community as to what constitutes a 

species and this has not been a major source of controversy in most listing 

decisions.3

 Disagreements typically arise over whether entities that are 

genetically, morphologically, or behaviorally distinct, but not distinct 

1

In total, these experts identified 25 species where they believed there was significant 

scientific controversy regarding listing the species. We limited our review to only those 

species that had been formally listed within the past 10 years; we excluded 14 species from 

our review either because the species was not listed or because it was listed prior to 1993.

2

16 U.S.C. §1532(16).

3

While there are differing definitions for the term species, it is often defined as groups of 

interbreeding natural populations that are reproductively isolated from other such groups.
Appendix IV

The Nature of Scientific Controversy 

Surrounding Listing and Critical Habitat 

Decisions

Page 59 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

enough to merit the rank of species; qualify for protection as a distinct 

population segment (DPS). Under Service policy, to be identified as a DPS, 

a population segment must be both discrete and significant.4

 In order to be 

discrete, the population must be markedly separate from other populations 

as a consequence of physical, physiological, ecological, or behavioral 

factors. If a population segment is considered discrete, its biological and 

ecological significance will then be considered. This consideration would 

include such factors as evidence that the loss of the population would 

result in a significant gap in the range of a species.

For example, disagreement surrounded the decision to list the population 

of the Sonoma County California tiger salamander, a large terrestrial 

salamander that is native to California. According to critics of the listing 

decision, the results of genetic testing did not show the salamander to be 

distinct, or discrete, from other populations of the California tiger 

salamander and therefore the population did not qualify as a DPS. The 

Service disagreed with the critics’ interpretation of the data, stating that it 

believed the data referred to by the critics show the salamander to be 

distinct from other populations. The Service said that additional sampling 

and genetic work provided further substantial evidence of the genetic 

discreteness of the population. Additionally, the Service relied on the 

salamander’s geographic isolation in making a determination that the 

population qualified for protection as a DPS. 

Service policy also allows international governmental boundaries that 

delineate differences in the management of the species or its habitat to be 

used to determine if a species meets the discrete criterion. Some critics 

have argued against using international boundaries as a criterion to define 

a DPS. For example, critics of the decision to list the Arizona population 

segment of the cactus ferruginous pygmy-owl stated that the Service had 

no biological or regulatory authority to rely on international boundaries to 

draw a distinct population segment. The pygmy-owl is a small bird that 

occurs in the southwestern United States extending south into Mexico. 

The Service recognizes that using international boundaries as a measure of 

discreteness may introduce a nonbiological element to the recognition of a 

distinct population segment. However, in its policy, the Service determined 

that it is reasonable to recognize units delimited by international 

boundaries when these units coincide with differences in the management, 

4

61 Fed. Reg. 4722 (Feb. 7, 1996).
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status, or exploitation of a species. In the case of the pygmy-owl, the 

Service reported the status of the owl in the United States is different from 

that in Mexico, and Arizona is the only area within which the government 

of the United States can affect protection and recovery for the species, so it 

was appropriate to protect the pygmy-owl as a DPS.

In its review of science and the Endangered Species Act, the National 

Research Council found that although it may be appropriate to delineate 

population segments based on political boundaries, there are no scientific 

reasons to do so as these boundaries often do not always coincide with 

major natural geographic boundaries.5

 To provide more scientific 

objectivity in identifying distinct population segments, the Council 

recommended that the Service define a distinct population segment based 

solely on scientific grounds and limit the definition to segments of 

biological diversity containing the potential for a unique evolutionary 

future. Such segments would be determined by looking at such factors as a 

population’s morphology (or physical appearance), behavior, genetics and 

geographical separation or isolation from other populations. Service 

officials agree that the inclusion of international boundaries in determining 

whether a population segment is discrete is sometimes undertaken as a 

matter of policy rather than science. However, the Service believes that 

using international borders is appropriate and necessary to comply with 

congressional intent. When there are international boundaries that 

coincide with differences in the management, status, or exploitation of a 

species, as described above, the Service stated that it is appropriate to 

recognize these borders when making a listing determination.

Scientific disagreement also surrounds the status of a species and the 

degree to which identified threats imperil it. When making a listing 

determination, the Service must evaluate a species’ status, such as where it 

occurs or its population numbers, and the degree of threat it faces. The 

Service can determine that a species is threatened or endangered because 

of any of several factors such as the destruction of habitat, disease or 

predation, or other natural or manmade factors affecting the species’ 

survival. Several of the scientific disputes that we encountered centered on 

how widespread the species in question is or how intense or significant the 

threats to the species are. For example, state agencies commenting on the 

proposal to list the Canada lynx said that the rule failed to demonstrate 

5

National Research Council, Science and the Endangered Species Act (Washington D.C.: 

National Academy Press, 1995) 71-93.
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there were significant reductions to the species’ population. Critics of the 

rule said that the scientific information—which was largely in the form of 

one comprehensive report—failed to assess lynx population size, status, 

and trends. The Service agreed that the available information concerning 

lynx population status, trends, and historic range is limited. However, after 

reviewing historic and current records for both Canada and the United 

States, sightings and track records, personal communications with lynx, 

hare, and forest ecology experts, and a review of all available literature, the 

Service said it was able to make several conclusions about the status of the 

lynx and found that it warranted listing as threatened.

Figure 5: Canada lynx

Note: The Canada lynx is a medium-sized cat that is adapted for hunting in the deep snow, and is 

known to prey primarily upon the snowshoe hare. In the contiguous United States, the distribution of 

the lynx is known from the Cascade and Rocky Mountain Ranges in the West, the western Great 

Lakes Region, and along the Appalachian Mountain Range of the northeastern portion of the country.

Additionally, critics of the proposal to list the lynx claimed that the Service 

failed to demonstrate significant threats to the lynx’s survival. For example, 

some stated that there is little evidence to support claims that current 

management practices, including timber harvesting and human access, 
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adversely affect the lynx. While the Service acknowledged the lack of 

quantifiable information to determine whether some of the possible threats 

have or would have resulted in lynx declines, it concluded that the factor 

threatening lynx in the contiguous United States is the lack of guidance in 

existing federal land management plans for conservation of lynx and lynx 

habitat.

Service officials told us that it is important to consider both the threats and 

the status of the species when making a listing determination. For example, 

if only a species’ population numbers were considered, it might appear to 

be abundant. Once the threats are factored in, however, the species might 

be threatened or endangered. On the other hand, if the species numbers are 

low but the species faces no considerable threats, it may not warrant 

protection under the act. 

Critical Habitat Experts and others we spoke to identified 10 species where there was 

scientific controversy concerning the decision to designate critical habitat 

for them.6

 For example, one concern is whether the area chosen as critical 

habitat is sufficiently defined or the overall information used to support the 

designation is adequate. Most of the identified species are widespread or 

occur in rapidly developing areas, such as southern California. 

One of the major sources of disagreement is the way in which the Service 

identifies land to be included in critical habitat. The Service is required to 

designate as critical habitat those areas that it deems essential to a species’ 

conservation and that may require special management considerations and 

protection. To reach this conclusion, the Service describes the species’ 

habitat needs for conservation, or the species’ “primary constituent 

elements,” such as nesting or spawning grounds, feeding sites, or areas 

with specific geologic features or soil types. The Service’s regulations also 

require the delineation of critical habitat using reference points and lines as 

found on standard topographic maps of the area. The Service uses written 

descriptions and/or maps to outline the areas it considers critical habitat 

for a listed species. In some cases, when maps are used to outline the area, 

6

In total, these experts identified 13 species where there was scientific controversy 

concerning their critical habitat designation. We limited our review to species that had 

critical habitat formally designated within the past 10 years; we excluded 3 species from our 

review either because the species critical habitat was not yet finalized, or because it was 

designated prior to 1993.
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parts of the area that fall within the mapped boundaries do not contain the 

primary constituent elements defined by the Service. For example, building 

structures, roads, or other major structures, such as an airport, may fall 

within the mapped boundaries of critical habitat, but are not suitable 

habitat. The Service maintains that these areas would not be considered 

critical habitat because they do not contain the primary constituent 

elements needed by the species. The Service stated that the precise 

mapping of critical habitat boundaries is impractical or impossible because 

the legal descriptions for these precise boundaries would be unwieldy.

The scientific controversy surrounding many of the critical habitat 

proposals that we reviewed stems from disagreement or confusion over 

which areas within the land outlined by the Service would count as critical 

habitat. Critics responding to these proposed rules often complained that 

the Service’s definitions of primary constituent elements were vague or too 

broad to be useful. Additionally, several critics found the Service’s 

assertion that only areas containing primary constituent elements would be 

considered critical habitat to be confusing, noting that it did not allow for a 

discrete boundary. In some instances, landowners voiced concerns that 

their property fell within proposed critical habitat boundaries even though 

the land did not seem to contain the primary constituent elements. For 

example, critics of the proposed critical habitat of the California red-legged 

frog stated that the Service’s description of the critical habitat was vague 

and did not specifically identify the locations of the frog’s habitat. 
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Figure 6: California red-legged frog

Note: The California red-legged frog is the largest native frog found in the western United States, and 

its critical habitat consisted of over 4 million acres in California. 

Critics of the rule stated that the proposal was confusing and that 

landowners would be forced to survey for the frog when undertaking a 

project. Such an action, they contended, is improper because it places the 

onus on private landowners to make sure their land does not contain 

critical habitat. The Service stated that due to the mapping unit it used it 

was not able to exclude all nonessential lands, such as roads. According to 

the Service, because these areas do not contain the primary constituent 

elements, federal agencies would not be required to consult the Service 

before taking action.

We also identified scientific disagreement stemming from designations 

made for species that require dynamic habitats. Designating critical habitat, 

which requires selecting a fixed habitat area, can be particularly difficult 

when a listed species may require a habitat that is dynamic, or changing, in 

nature. For example, lands that have been burned, cleared, or otherwise 

disturbed may be essential to a species or may be important for only 
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certain periods of a species’ life cycle. Many landscapes change because of 

natural causes, such as the age and make-up of a forest, and therefore it 

may be difficult to designate one particular area as habitat because the area 

may change over time, causing a change in the value of the habitat for the 

listed species. For example, scientific disagreement surrounded the critical 

habitat designation of the Southwestern willow flycatcher partly because 

of the bird’s changing habitat requirements. Comments received on the 

proposed critical habitat rule stated that because riparian habitats are in a 

constant state of change, any boundaries defined as critical habitat would 

also be subject to change. Further, according to critics, the boundaries 

described by the Service did not meet regulatory requirements because 

they were difficult to interpret and could change seasonally. In the final 

rule designating critical habitat, the Service agreed that its original 

boundaries of critical habitat did not incorporate the dynamic nature of 

riparian systems. To resolve this issue, the Service stated that the final 

boundaries would be established in accordance with the 100-year flood 

zone, which would include most changes in stream flow and most seasonal 

changes.
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Figure 7: Southwestern willow flycatcher

Note: The Southwestern willow flycatcher is a small bird found in the southwestern United States. The 

designation of the flycatcher consisted of more than 500 miles of river habitat in the southwest.

In addition to controversy surrounding the identification of specific areas 

for critical habitat, many critics of the proposed rules that we reviewed 

argued that the Service had insufficient information on which to base its 

determination and that the Service should not designate critical habitat 

until the habitat requirements of the species could be better defined. Other 

critics objected to the Service’s use of unpublished or otherwise 

unavailable data, stating that this type of information is inadequate to 

support critical habitat designations. Service officials said that they have 

been required to complete critical habitat decisions under short time 

frames because of court-imposed deadlines. According to Service officials, 

given the resource and time constraints under which Service scientists 

work, scientists are often unable to collect new information and agree that 

the information available may be limited. Thus, the Service relies on both 
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unpublished and published information and will use whatever scientific 

information it deems credible to help make a determination.
Page 68 GAO-03-803 Additional Guidance Needed for Critical Habitat Designations

Appendix V

GAO Contact and Staff Acknowledgments ApendxiV

GAO Contact Trish McClure (202) 512-6318

Staff 

Acknowledgments

In addition to the individual named above, Bob Crystal, Charlie Egan, 

Doreen Stolzenberg Feldman, Alyssa M. Hundrup, Nathan Morris, and Judy 

Pagano made key contributions to this report.

(360260)
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