FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

KERN COUNTY FARM BUREAU; KERN 

COUNTY WATER AGENCY; NORTH

KERN COUNTY WATER STORAGE

DISTRICT; COALITION OF PRIVATE

PROPERTY RIGHTS; ROSEDALE-RIO

BRAVO WATER STORAGE DISTRICT;

SEMITROPIC WATER STORAGE

DISTRICT; WHEELER RIDGE

MARICOPA WATER STORAGE

DISTRICT; COUNTY OF KERN,

Plaintiffs-Appellants,

v. No. 04-15540

DAVE ALLEN, Regional Director of D.C. No.  the U.S. Fish and Wildlife Service, CV-02-05376-AWI

Region 1; STEVEN A. WILLIAMS, OPINION

Director of the U.S. Fish and

Wildlife Service; GALE A. NORTON,

Secretary of the Interior; UNITED

STATES DEPARTMENT OF THE

INTERIOR; U.S. FISH AND WILDLIFE

SERVICE,

Defendants-Appellees,

and

CENTER FOR BIOLOGICAL DIVERSITY,

Intervenor-DefendantAppellee. 

Appeal from the United States District Court

for the Eastern District of California

Anthony W. Ishii, District Judge, Presiding

6855
Argued and Submitted

February 16, 2006—San Francisco, California

Filed June 20, 2006

Before: J. Clifford Wallace, Michael Daly Hawkins, and

Sidney R. Thomas, Circuit Judges.

Opinion by Judge Hawkins

6856 KERN COUNTY FARM BUREAU v. ALLEN
COUNSEL

Robert D. Thornton, Nossaman, Guthner, Knox & Elliott,

Irvine, California, for the plaintiffs-appellants. 

Matthew J. Sanders, U.S. Department of Justice, Environmental & Natural Resources Division, Washington, D.C., for the

defendants-appellees. 

Matt Kenna, Kenna & Hickcox, Durango, Colorado, for the

intervenor-defendant-appellee. 

M. Reed Hopper, Pacific Legal Foundation, Sacramento, California, for amicus curiae Pacific Legal Foundation. 

6858 KERN COUNTY FARM BUREAU v. ALLEN
OPINION

HAWKINS, Circuit Judge: 

Kern County Farm Bureau, et al. (“Kern”), appeal from the

district court’s judgment denying their claim against the U.S.

Fish & Wildlife Service (“FWS”) for listing the Buena Vista

Lake shrew (“the BVL shrew”) as an endangered species,

contending that FWS violated the Endangered Species Act

(“ESA”) and the Administrative Procedure Act (“APA”) by

failing to provide public review and comment on new studies

that became available after the close of the comment period,

not basing its listing decision on the best scientific data available, not summarizing the data underlying its decision, and

not showing the relationship between the data and its decision. Because the post-comment information was only important, not critical, to FWS’s decision, and given the deference

owed to agencies in making such scientifically-based decisions, we affirm the district court’s judgment. 

I. Factual History

The BVL shrew is a subspecies of ornate shrews endemic

to Kern County, California. 67 Fed. Reg. 10101 (Mar. 6,

2002) (codified at 5 C.F.R. pt. 17). Fewer than thirty are

known to exist. Id. at 10110. 

On June 1, 2000, FWS published a rule proposing to list the

BVL shrew as an endangered subspecies under the ESA. 65

Fed. Reg. 35033 (June 1, 2000). The proposal explained that

only thirty-eight BVL shrews had been observed since their

rediscovery in 1986, and that the only known population

existed in a small wetland area on private property. Id. at

35033-34. The proposal emphasized that the amount of suitable habitat for the BVL shrew had been significantly reduced

while noting that additional patches of habitable land in the

area that might have supported the BVL shrew were “marginal at best and would not likely [have] support[ed] a signifiKERN COUNTY FARM BUREAU v. ALLEN 6859
cant number of animals.” Id. at 35036 (citation omitted). The

Proposed Rule explained that this “loss and fragmentation of

habitat due to human activities” was “[t]he primary cause of

decline of the [BVL] shrew.” Id. Additionally, FWS found

that the BVL shrew was threatened “by agricultural activities,

modifications and potential impacts to local hydrology, uncertainty of water delivery . . . , possible toxic effects from selenium poisoning, and by random naturally occurring events.”

Id. at 35038. FWS concluded that there was a high probability

that these threats would have “result[ed] in the extinction of

the [BVL] shrew . . . .” Id.

FWS opened a sixty-day comment period for the proposal,

seeking information about threats to the BVL shrew, locations

of any additional populations, and “the range, distribution,

and population size and genetics of this subspecies.” Id. at

35039. FWS then reopened the comment period for another

sixty days “to provide all interested parties additional opportunity to . . . [comment] on the proposal.” 65 Fed. Reg. 49530

(Aug. 14, 2000). Further, FWS “solicited the expert opinions

of five independent specialists regarding the biological and

ecological information about the [BVL] shrew contained in

the proposed rule.” 67 Fed. Reg. at 10105. Of the four peer

reviewers who responded within the comment period, three

“stated that the proposed rule was an accurate summary of the

species biology and status,” while one “felt that additional

surveys and improved management of known populations . . .

could eliminate the need to list the species.” Id. at 10106.

Ultimately, three supported the listing, while the fourth

remained neutral.1

After the comment period, but before issuance of the Final

Rule, three new studies became available. Two of the studies

dealt with morphological and genetic variations among the

multiple subdivisions of ornate shrews, while the third

1The fifth peer reviewer, Daniel Williams, responded one year after the

open comment period and recommended postponing the listing. 

6860 KERN COUNTY FARM BUREAU v. ALLEN
assessed the distribution, habitat, and status of the BVL

shrew. See infra Section IV.A. Following the release of these

new studies, FWS did not reopen the public comment period.

Instead, on March 6, 2002, it published the Final Rule listing

the BVL shrew as an endangered subspecies. 67 Fed. Reg. at

10101. The Final Rule responded to various comments on the

Proposed Rule and incorporated some of the data from the

new studies. Nevertheless, it listed factors nearly identical to

those mentioned in the Proposed Rule to justify its listing

decision and concluded that listing the BVL shrew as endangered was “the preferred action.” 67 Fed. Reg. at 10110. 

Kern soon thereafter filed its complaint, primarily alleging

various APA and ESA violations. After a bench trial, judgment was entered in favor of FWS, and Kern filed this appeal.

II. Statutory Framework

The APA requires federal agencies to publish a general

notice of proposed rule making in the Federal Register to

“give interested persons an opportunity to participate in the

rule making through submission of written data, views, or

arguments with or without opportunity for oral presentation,”

and “[a]fter consideration of the relevant matter presented, . . .

[to] incorporate in the rules adopted a concise general statement of their basis and purpose.” 5 U.S.C. § 553(b)-(c); see

also 16 U.S.C. § 1533(b)(4) (ESA listing decisions must comply with the APA, 5 U.S.C. § 553). 

Under the ESA, an endangered species is “any species

which is in danger of extinction throughout all or a significant

portion of its range . . . .” 16 U.S.C. § 1532(6).2 A “species”

includes “any subspecies of . . . wildlife . . . and any distinct

population segment of any species of . . . wildlife which interbreeds when mature.” 16 U.S.C. § 1532(16). The decision to

2FWS is one of the agencies responsible for administering the ESA. See

50 C.F.R. § 402.01(b) (1986). 

KERN COUNTY FARM BUREAU v. ALLEN 6861
list a species as endangered is based on five statutorily prescribed factors, any one of which may support a listing determination: (1) “the present or threatened destruction,

modification, or curtailment of its habitat or range;” (2) “overutilization for commercial, recreational, scientific, or educational purposes;” (3) “disease or predation;” (4) “the

inadequacy of existing regulatory mechanisms;” or (5) “other

natural or manmade factors affecting its continued existence.”

16 U.S.C. § 1533(a)(1)(A)-(E). 

Listing determinations must be made “solely on the basis

of the best scientific and commercial data available . . . .” 16

U.S.C. § 1533(b)(1)(A). Additionally, FWS must include in

any proposed or final listing decision “a summary . . . of the

data on which such regulation is based and [must] show the

relationship of such data to such regulation . . . .” 16 U.S.C.

§ 1533(b)(8). 

III. Standard of Review

The APA provides that final agency action shall be set

aside if it is “arbitrary, capricious, an abuse of discretion, or

otherwise not in accordance with the law,” or if it is taken

“without observance of procedure required by law.” 5 U.S.C.

§ 706(2)(A), (D); accord Idaho Farm Bureau Fed’n v. Babbitt, 58 F.3d 1392, 1401 (9th Cir. 1995). The arbitrary and

capricious standard is “highly deferential, presuming the

agency action to be valid and [requires] affirming the agency

action if a reasonable basis exists for its decision.” Indep.

Acceptance Co. v. California, 204 F.3d 1247, 1251 (9th Cir.

2000) (quotations and citations omitted). Under such deferential review, we may not substitute our judgment for that of the

agency. Marsh v. Or. Natural Res. Council, 490 U.S. 360, 376

(1989). 

Unlike substantive challenges, however, our review of an

agency’s procedural compliance is exacting, yet limited. See

Coalition For Gov’t Procurement v. Fed. Prison Indus., Inc.,

6862 KERN COUNTY FARM BUREAU v. ALLEN
365 F.3d 435, 457 (6th Cir. 2004) (citing Natural Res. Def.

Council, Inc. v. SEC, 606 F.2d 1031, 1045, 1048-49 (D.C.

Cir. 1979)); Campanale & Sons, Inc. v. Evans, 311 F.3d 109,

116 (1st Cir. 2002). We review de novo but are limited to

ensuring that “ ‘statutorily prescribed procedures have been

followed.’ ” Campanale & Sons, 311 F.3d at 116 (quoting

Natural Res. Def. Council, Inc., 606 F.2d at 1045). Further,

we determine “the adequacy of the agency’s notice and comment procedure, without deferring to an agency’s own opinion of the . . . opportunities it provided.” Natural Res. Def.

Council v. EPA, 279 F.3d 1180, 1186 (9th Cir. 2002).

IV. Discussion

A. Notice and Comment for New Studies

[1] Integral to an agency’s notice requirement is its duty to

“identify and make available technical studies and data that it

has employed in reaching the decisions to propose particular

rules. An agency commits serious procedural error when it

fails to reveal portions of the technical basis for a proposed

rule in time to allow for meaningful commentary.” Solite

Corp. v. EPA, 952 F.2d 473, 484 (D.C. Cir. 1991) (quotations,

punctuation, and citation omitted). Yet, “[n]othing prohibits

[an a]gency from adding supporting documentation for a final

rule in response to public comments.” Rybachek v. EPA, 904

F.2d 1276, 1286 (9th Cir. 1990). After publishing a proposed

rule, agencies often receive new information, which in turn

improves the accuracy of agency action: 

It is perfectly predictable that new data will come in

during the comment period, either submitted by the

public with comments or collected by the agency in

a continuing effort to give the regulations a more

accurate foundation. The agency should be encouraged to use such information in its final calculations

without thereby risking the requirement of a new

comment period. 

KERN COUNTY FARM BUREAU v. ALLEN 6863
BASF Wyandotte Corp. v. Costle, 598 F.2d 637, 644-45 (1st

Cir. 1979). 

[2] Accordingly, the public is not entitled to review and

comment on every piece of information utilized during rule

making. Instead, an agency, without reopening the comment

period, may use “supplementary data, unavailable during the

notice and comment period, that expands on and confirms

information contained in the proposed rulemaking and

addresses alleged deficiencies in the pre-existing data, so long

as no prejudice is shown.” Idaho Farm Bureau Fed’n, 58 F.3d

at 1402 (quoting Solite Corp., 952 F.2d at 484) (internal quotations omitted). 

In Idaho Farm Bureau Federation, we held that FWS committed procedural error in listing the Bruneau Hot Springs

Snail as an endangered species because it failed to provide the

public with an opportunity to review and comment on new

material in the record. 58 F.3d at 1404. The new material “did

not merely supplement or confirm existing data,” but rather

“provided the only scientific information on the cause of the

decline in [the Snail’s habitat,]” and, therefore, constituted

“unique information that was not duplicated in other reports.”

Id. at 1402-03. The need for notice and comment was “greatly

heightened because FWS relied largely on the [new] study to

support its final rule.” Id. at 1403. In particular, the study

“was critical to FWS’[s listing] decision,” because “FWS support[ed] its key analysis by citing the [new] study.” Id. at

1403; see also Ober v. EPA, 84 F.3d 304, 314-15 (9th Cir.

1996) (reopening the public comment period because the

additional materials were relied on and “critical” to the agency’s decision). Additionally, the need for public comment was

exacerbated by the questionable accuracy of the new study.3

We noted that in Idaho Farm Bureau Fed’n, 58 F.3d at 1403,

3The report was a provisional draft that the FWS did not want released

to the public and was discovered to have had several errors. Idaho Farm

Bureau Fed’n, 58 F.3d at 1403. 

6864 KERN COUNTY FARM BUREAU v. ALLEN
the “[o]pportunity for public comment is particularly crucial

when the accuracy of important material in the record is in

question.” 

In contrast, the D.C. Circuit, in Solite Corp., upheld the

EPA’s failure to provide a public opportunity to comment on

new data used in the Final Rule. 952 F.2d at 484-85. The EPA

had “replaced one report with a later report as the source of

data on which final quantitative measurements were based.”

Idaho Farm Bureau Fed’n, 58 F.3d at 1402 (explaining Solite

Corp., 952 F.2d at 484). In affirming the EPA’s actions, the

court found it significant that the accuracy of the new data

was not challenged, that the record did not suggest that the

agency hid the information or conducted rule making in bad

faith, that the new data confirmed prior assessments, and that

the agency’s methodology remained constant. Solite Corp.,

952 F.2d at 484-85. 

Here, the first post-comment study was a range-wide

genetic study of 251 shrew specimens by Dr. Jesus Maldonado. Jesus E. Maldonado, et al., Tripartite genetic subdivisions in the ornate shrew (Sorex ornatus), 10 MOLECULAR

ECOLOGY 127 (2001) [hereinafter 2001 Maldonado Study].

This study evaluated genetic variations among ornate shrews

at twenty localities and postulated that ornate shrews in California could be organized into three “clades” — northern,

central (to which the BVL shrew belongs), and southern.4Id.

The study noted that “[t]he ornate shrew is one of the most

threatened small mammals” in California, “primarily due to

destruction of wetlands and riparian habitats . . . .” Id. at 143.

The study did not purport to change the taxonomic classification of the BVL shrew, referring to it as a separate subspecies.

Id.

4A clade is a “group of organisms, such as a species, whose members

share homologous features derived from a common ancestor.” American

Heritage Dictionary of the English Language (4th ed. 2000), available at

http://www.bartleby.com/reference. 

KERN COUNTY FARM BUREAU v. ALLEN 6865
A second post-comment study, also conducted by Dr. Maldonado,5

 examined the morphological characteristics of over

500 ornate shrew skulls throughout the species’ range to

determine if any differences existed, and, if so, whether they

corresponded to the three genetic clades identified in his 2001

study. See Jesus E. Maldonado, Discordant Patterns of Morphological Variation in Genetically Divergent Populations of

Ornate Shrews (Sorex Ornatus) (forthcoming 2004) [hereinafter Morphological Study]. Maldonado found “significant morphological differences between ornate shrew populations,”

which did not correspond to the three genetic clades he had

previously identified. Id. at 12. Further, the morphological

differences between subspecies “seem[ed] to portray the patterns of variation [between shrew populations] better than the

genetic regions” identified in the 2001 Maldonado Study. Id.

He concluded that the “current boundaries for the seven subspecies that were analyzed in [the] study[ ] correspond[ed] to

morphological divergence and should therefore continue to be

considered [Evolutionarily Significant Units].”

6

Id. at 13. 

The third post-comment study, authored by Daniel Williams and Adam Harpster, assessed “the distribution, habitat

association, and population status of the [BVL] shrew” by

trapping for shrews at six sites.7See Daniel Williams & Adam

Harpster, Status of the Buena Vista Lake Shrew (Sorex Ornatus Relictus) (Oct. 29, 2001) (unpublished report, on file with

the U.S. Bureau of Reclamation) [hereinafter Status Review].

The trapping caught sixteen shrews at three of the six sites. Id.

5This study was unpublished during the rule making process, but was

later published. Discordant Patterns of Morphological Variation in Genetically Divergent Populations of Ornate Shrews (Sorex Ornatus), 85 J. OF

MAMMOLOGY 886 (2004). 

6An Evolutionarily Significant Unit is “a set of populations that has

been historically isolated and, accordingly, is likely to have a distinct

potential.” Id. at 13 (quotations and citation omitted). 

7The study was commissioned by the Central Valley Project Improvement Act and administered, in part, by FWS. 

6866 KERN COUNTY FARM BUREAU v. ALLEN
at 9. These three additional BVL shrew populations were discovered in wetland and riparian habitat that had been reduced

to “10 small, degraded, and scattered remnants . . . .” Id. at

10. The Status Review speculated “that ornate shrews may

reside on actively farmed ground, or . . . cultivated fields,” but

limited its hypothesis to ornate shrews generally (not BVL

shrews), and based its belief on a survey of “unknown significance.” Id. at 13-14. Further, it surmised that BVL shrews

“also rarely will be found in more arid, upland communities,”

but noted that such communities “are extremely reduced and

isolated in small parcels,” and “might provide extremely low

quality habitat for [BVL] shrews . . . .” Id. at 13. 

Although the study deduced that “measures to conserve and

enhance [BVL shrew] populations are justified,” and cautioned that it “[did] not have insight into the size and extent

of [BVL shrew] populations,” the authors did “not believe

that [BVL] shrews are endangered now, nor are there foreseeable threats to remaining populations in the near future.” Id.

at 16. It reached this conclusion, in part, by noting that several

possible initiatives in the region “hold great promise for

greatly enhancing populations of [BVL] shrews.” Id. Still, the

study found that “the long-term persistence of [BVL] shrews

depends upon maintenance of riparian and wetland communities in the southern Tulare Basin . . . and enhancing the size

and connectivity between the small and mostly isolated habitats where the shrews currently are found.” Id.

Like the petitioners in Solite Corp., Kern does not point to

inaccuracies in the new studies. Id. at 484. Nor does the

record suggest that FWS hid the information from the public

or conducted rule making in bad faith. Rather, Kern contends

that the new studies were critical to the listing decision. 

The district court correctly concluded that the new studies

merely supplemented the data in the Proposed Rule. Unlike

the post-comment study in Idaho Farm Bureau Federation,

the new materials do not provide the sole, essential support

KERN COUNTY FARM BUREAU v. ALLEN 6867
for the listing decision. Instead, as in Solite Corp., the studies

confirm and expand on existing data, providing additional

grounds for the well-supported conclusions in the Proposed

Rule. Id. at 485. Moreover, the new studies did not alter the

justifications or conclusions that were vital to the listing decision. Just like the Proposed Rule, FWS concluded in the Final

Rule that the BVL shrew was a distinct subspecies threatened

with extinction, explaining that few BVL shrews remain, that

the amount of suitable habitat has been significantly reduced,

and that several factors jeopardize the BVL shrew’s continued

existence. Indeed, the entire discussion of the extinction factors in the Final Rule strongly resembles the factors provided

in the Proposed Rule. Compare 67 Fed. Reg. at 10106-10 with

65 Fed. Reg. at 35036-38. 

Despite the limited use of the new studies and the analytical

symmetry between the two rules, Kern argues that further

notice and comment was required, basing its claim on three

assertions: (1) the new studies provided crucial information

on whether the BVL shrew is a distinct subspecies; (2) the

new studies provided crucial information on whether the BVL

shrew is in danger of extinction; and (3) the new studies

undermined the listing decision. 

1. Subspecies Distinction 

[3] To be eligible for an endangered species listing, an animal must first be classified, at a minimum, as a distinct subspecies. See 16 U.S.C. § 1532(16). FWS used the 2001

Maldonado Study and the Morphological Study in the Final

Rule only to describe further the distinct morphological and

genetic characteristics of the BVL shrew subspecies. 67 Fed.

Reg. at 10101. FWS sought to “add depth” to its morphological discussion by incorporating these studies into the Final

Rule. The Proposed Rule primarily supported the conventional conclusion that the BVL shrew is a distinct subspecies

by citing to a 1932 study by Dr. Grinnell, which, according

to FWS, is the only scientifically valid, peer-reviewed, and

6868 KERN COUNTY FARM BUREAU v. ALLEN
published taxonomic treatment of the BVL shrew. 65 Fed.

Reg. at 35033-34. The Maldonado studies confirmed FWS’s

previous conclusion by providing additional data on the BVL

shrew’s morphological and genetic characteristics. Having

reached an identical conclusion that affirmed its alreadysupported subspecies classification, FWS’s use of the Maldonado studies in the Final Rule was far from critical to its

listing decision. 

2. Danger of Extinction 

[4] Upon concluding that the BVL shrew was a distinct

subspecies, FWS sought to determine whether the shrew was

“in danger of extinction throughout all or a significant portion

of its range . . . .” 16 U.S.C. § 1532(6). FWS found that few

BVL shrews remained and determined that several factors

subjected the BVL shrew to a substantial risk of extinction

throughout its range. The Final Rule used the Status Review

to expand on its discussion of the BVL shrew’s population

and range, integrating the Status Review’s data with all that

was known and cited in the Proposed Rule. Some of the revisions provided by the Status Review were unquestionably significant. In discovering three new populations of BVL shrews,

the Status Review nearly doubled the number of known

shrews to thirty. Further, the Status Review provided more

detailed information on the current range of the BVL shrew

and on the suitability of various habitats. None of the new

information, however, adversely affected FWS’s underlying

reasons for its conclusion.8 The Status Review’s data simply

supplemented the existing data, confirming that few BVL

shrews existed and that their most suitable habitat remained

fragmented, degraded, and scattered. Status Review at 10-12.

Because the Status Review provided useful data that supplemented FWS’s existing understanding of the BVL shew, but

8One FWS official found that the Status Review “ma[de] a stronger case

for listing than delisting,” while another determined that the data from the

Status Review “d[id] not change the conclusion for the final rule.” 

KERN COUNTY FARM BUREAU v. ALLEN 6869
did not alter the primary conclusions from the Proposed Rule,

it was not critical to FWS’s decision. 

3. Listing Decision Validity 

Kern’s primary objection to FWS’s use of the Status

Review essentially emanates from the Status Review’s opposing conclusion that the BVL shrew should not be listed as

endangered. Despite the conflicting opinion, FWS concluded

that the data from the Status Review was consistent with its

listing decision. Kern’s concern is misplaced because FWS is

not required to accept the Status Review’s conclusion, but

rather simply must use the Status Review’s data in reaching its

listing decision. See infra Section IV.B; 16 U.S.C.

§ 1533(b)(1)(A). To the extent that Kern disputes FWS’s

interpretation of the data in the new studies or seeks an evaluation of FWS’s data and conclusion, its claim constitutes a

substantive challenge to the listing decision. 

In fact, much of Kern’s argument appears to be a substantive claim couched in alleged procedural violations. Kern’s

principal contention is less concerned with the degree to

which the Final Rule relies on the new studies than it is on the

extent to which the new studies undercut the Final Rule. Kern

initially presents a procedural argument that the new studies

were critical to the listing decision and thus require public

comment, but then spends most of its analysis attempting to

demonstrate how the three studies actually undermine the key

premises in FWS’s listing decision (a substantive issue meriting the more stringent arbitrary and capricious review).

Kern’s procedural claims thus appear inextricably intertwined

with its substantive contention that FWS misinterpreted the

information from the new studies. Because Kern emphasizes

that it only raises procedural violations in this appeal, however, such substantive issues are not properly before us. 

4. Conclusion 

[5] Ultimately, the new studies were not vital to FWS’s

decision as they were not used to introduce a new premise, to

6870 KERN COUNTY FARM BUREAU v. ALLEN
justify independently the final decision, or to reach a different

conclusion. Instead, the Final Rule discusses virtually identical factors as those in the Proposed Rule in deciding to list the

BVL shrew. Having used the new studies merely to refine and

expand on its pre-existing data, FWS was not required to

reopen the public comment period. 

B. Best Scientific Data Available 

[6] Kern argues that FWS failed to utilize the data from the

three studies in reaching its listing decision and, therefore,

violated the ESA’s requirement to base its determination on

the “best scientific and commercial data available.” 16 U.S.C.

§ 1533(b)(1)(A ). The best available data requirement “merely

prohibits [an agency] from disregarding available scientific

evidence that is in some way better than the evidence [it]

relies on.” Southwest Ctr. for Biological Diversity v. Babbitt,

215 F.3d 58, 60 (D.C. Cir. 2000) (quotations omitted). Essentially, FWS “cannot ignore available biological information.”

Conner v. Burford, 848 F.2d 1441, 1454 (9th Cir. 1988). 

[7] Because Kern “point[s] to no data that was omitted

from consideration,” Building Indus. Ass’n of Superior California v. Norton, 247 F.3d 1241, 1246 (D.C. Cir. 2001) (quotations omitted), this second claim also fails. “[A]bsent

superior data . . . occasional imperfections do not violate

§ 1533(b)(1)(A).” Id. at 1247. Kern does not allege that FWS

actually omitted the three new studies from the Final Rule.

The Final Rule contains at least twenty citations to the three

new studies. Instead, Kern’s claim is hitched to its assertion

that FWS misinterpreted the new studies. See supra Section

IV.A.3. Kern essentially contends that all three studies undermine the Final Rule and, therefore, FWS “in reality ignored

them.” 

[8] The record, however, is replete with examples to the

contrary. FWS thoroughly evaluated and incorporated the data

from all three studies in making its listing decision. The data

KERN COUNTY FARM BUREAU v. ALLEN 6871
from the studies are discussed and evaluated throughout the

Final Rule, and e-mail traffic from agency officials demonstrates that FWS examined the data from the new studies in

promulgating the Final Rule. Without any evidence in the

record that FWS ignored relevant information, we hold that

FWS satisfied its duty to base its listing determinations on the

best available data. 

C. Relationship of Data to Listing Decision

Finally, Kern contends that FWS failed to summarize the

data underlying the Final Rule and to show the relationship of

the data to the Final Rule, as required by 16 U.S.C.

§ 1533(b)(8). Kern supports its claim by listing various questions that it claims were left unanswered by FWS. We reject

Kern’s attempt to mandate that FWS answer its particular

questions before making a listing decision. FWS’s discussion

of the data and analysis of the extinction factors adequately

satisfied its ESA requirements. 

The Final Rule is extensively documented (citing over 100

sources) and contains abundant data and explanations supporting FWS’s ultimate decision. It comprehensively

describes the existing data on the BVL shrew, noting that

“there are less than 30 known individuals in four populations

. . . .” 67 Fed. Reg. at 10110. Such scarce numbers make the

BVL shrew “extremely vulnerable” to environmental impacts

and risks associated with small, restricted populations. Id.

These risks, which can lead to extinction, include “the loss or

alteration of essential elements for breeding, feeding, and

sheltering; the introduction of limiting factors into the environment such as poison or predators; and catastrophic random

changes or environmental perturbations, such as floods,

droughts, or disease.” Id. (citation omitted). 

The Final Rule goes on to examine particular threats to the

BVL shrew’s continued existence, finding that (1) the

“amount of suitable habitat for the [BVL] shrew has been sig6872 KERN COUNTY FARM BUREAU v. ALLEN
nificantly reduced over time,” resulting in the elimination of

“over 95 percent of the riparian vegetation and associated

marsh habitat” that could serve as suitable habitat for the BVL

shrew, id. at 10106, (2) the water supply is unable to support

ecosystem function throughout the BVL shrew’s entire habitat, id., (3) “[t]he small population size and restricted distribution [of BVL shrews] increases their vulnerability to epidemic

diseases” and deleterious genes through inbreeding, id. at

10107, (4) existing regulatory mechanisms “have not been

adequate in preventing the destruction of the limited [BVL]

shrew habitat,” id. at 10106-10, and (5) “[s]elenium toxicity

represents a serious threat to the continued existence and

recovery of the [BVL] shrew,” id. at 10107-08. Given the

“high potential that these threats could result in the extinction

of the [BVL] shrew,” the Final Rule concludes that “the preferred action is to list the [BVL] shrew as endangered.” Id. at

10110. Nothing more was required of FWS and, therefore,

Kern’s third claim is also without merit. 

V. Conclusion

[9] For the foregoing reasons, FWS adequately complied

with its APA and ESA procedural requirements. Accordingly,

we affirm the district court’s determination that no serious or

substantial reason exists to negate the listing and provide for

a new comment period. 

AFFIRMED.

KERN COUNTY FARM BUREAU v. ALLEN 6873