FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

DEFENDERS OF WILDLIFE,

Plaintiff-Appellant,

v.

RYAN ZINKE, Secretary, Department 

of the Interior; JAMES W. KURTH, 

Acting Director, U.S. Fish and 

Wildlife Service; MICHAEL D. NEDD, 

Acting Director, Bureau of Land 

Management,*

Defendants-Appellees,

and

SILVER STATE SOUTH SOLAR, LLC;

SILVER STATE SOLAR POWER SOUTH 

LLC,

Intervenor-Defendants-Appellees,

and

FIRST SOLAR, INC.; DESERT 

STATELINE, LLC,

Intervenor-Defendants.

No. 15-55806

D.C. No.

2:14-cv-01656-

MWF-RZ

OPINION

 * We substitute Ryan Zinke for Sally Jewell, James W. Kurth for 

Daniel M. Ashe, and Michael D. Nedd for Neil Kornze as DefendantsAppellees pursuant to Fed. R. App. P. 43(c)(2).
2 DEFENDERS OF WILDLIFE V. ZINKE

Appeal from the United States District Court

for the Central District of California

Michael W. Fitzgerald, District Judge, Presiding

Submitted February 17, 2017

Pasadena, California

Filed May 18, 2017

Before: MILAN D. SMITH, JR. and JOHN B. OWENS, 

Circuit Judges, and EDWARD R. KORMAN,** District 

Judge.

Opinion by Judge Milan D. Smith, Jr.

SUMMARY***

Endangered Species Act

The panel affirmed the district court’s summary 

judgment in favor of the Secretary of the Department of the 

Interior and other federal officials in an action brought by 

the Defenders of Wildlife concerning the possible impacts of 

the Silver State South solar project on the desert tortoise.

Plaintiff alleged that defendants violated the 

requirements of the Endangered Species Act and the 

 ** The Honorable Edward R. Korman, United States District Judge 

for the Eastern District of New York, sitting by designation.

*** This summary constitutes no part of the opinion of the court. It 

has been prepared by court staff for the convenience of the reader.
DEFENDERS OF WILDLIFE V. ZINKE 3

Administrative Procedures Act by issuing a Biological 

Opinion analyzing the effect of the Silver State South solar 

project on the desert tortoise that was, among other things, 

arbitrary and capricious.

The panel first rejected plaintiff’s contention that the 

Biological Opinion’s determination that Silver State South 

would not result in jeopardy to the desert tortoise 

impermissibly relied upon unspecified remedial measures. 

The panel held that: (1) the Biological Opinion did not rely 

on mitigation measures to make its no jeopardy 

determination; and (2) this Circuit’s precedents do not 

require mitigation measures to be identified or guaranteed 

when the mitigation measures themselves may be 

unnecessary.

The panel held that the Biological Opinion’s 

determination that Silver State South was “not likely to 

adversely affect the critical habitat of the desert tortoise,” 

which permitted the United States Fish and Wildlife Service 

to forego an adverse modification analysis, was neither 

arbitrary nor capricious. 

The panel held that the Biological Opinion’s failure to 

address the Fish and Wildlife Service’s comments to a 

Supplemental Environmental Impact Statement was not 

arbitrary or capricious because the Supplemental 

Environmental Impact Statement and the Biological Opinion 

evaluated substantially different plans. 

The panel held that because it could discern the 

Biological Opinion’s reasoning in concluding that Silver 

State South would not have significant edge effects and the 

record supports this conclusion, the Biological Opinion’s 

consideration of Silver State South’s edge effects was not 
4 DEFENDERS OF WILDLIFE V. ZINKE

arbitrary or capricious. The panel further held that the 

Biological Opinion did not establish an impermissibly vague 

trigger for reinitiating formal consultation over Silver State 

South. 

The panel concluded that because the Biological Opinion 

was neither legally nor factually flawed, the Bureau of Land 

Management permissibly relied upon the Biological Opinion 

in approving of the right-of-way for Silver State South.

COUNSEL

Eric R. Giltzenstein (argued) and William N. Lawton, Meyer 

Glitzenstein & Eubanks, Washington, D.C., for PlaintiffAppellant.

Varu Chilakamarri (argued), J. David Gunter II, and Andrew 

C. Mergen; John C. Cruden, Assistant Attorney General;

Environment and Natural Resources Division, United States 

Department of Justice, Washington, D.C., for DefendantsAppellees.

George T. Caplan (argued), Los Angeles, California, for 

Intervenor-Defendants-Appellees.

Lori Potter and Nicholas Clabbers, Kaplan Kirsch & 

Rockwell LLP, Denver, Colorado, for Amicus Curiae Clark 

County.
 DEFENDERS OF WILDLIFE V. ZINKE 5 

OPINION

M. SMITH, Circuit Judge: 

This case arises from the Bureau of Land Management 

(BLM)’s approval of a right-of-way on federal lands in 

Nevada for the construction of an industrial solar project, 

known as Silver State South, and the project’s possible 

impact on the desert tortoise. Plaintiff Defenders of Wildlife 

(DOW) contends that the Department of the Interior, the 

U.S. Fish and Wildlife Service (FWS), and the BLM 

(collectively, the Federal Defendants) violated the 

requirements of the Endangered Species Act (ESA), 

16 U.S.C. § 1531, et seq., and the Administrative Procedures 

Act (APA), 5 U.S.C. § 706, by issuing a Biological Opinion 

(BiOp) analyzing the effect of Silver State South on the 

desert tortoise that was arbitrary, capricious, and an abuse of 

discretion, and subsequently relying on the BiOp to grant the 

right-of-way. The district court concluded that the BiOp 

fully complied with both the ESA and APA, and granted 

summary judgment for the Federal Defendants and 

Intervenor-Defendants Silver State Solar Power South, LLC 

and Silver State South Solar, LLC (collectively, 

Defendants). We affirm. 

BACKGROUND

Statutory Framework

 “The Endangered Species Act of 1973, 16 U.S.C. 

§ 1531, et seq., ‘is a comprehensive scheme with the broad 

purpose of protecting endangered and threatened species.’” 

Conservation Cong. v. U.S. Forest Serv., 720 F.3d 1048, 

1050–51 (9th Cir. 2013) (quoting Ctr. for Biological 

Diversity v. U.S. Bureau of Land Mgmt., 698 F.3d 1101, 

1106 (9th Cir. 2012)). The ESA tasks the Secretary of the 
6 DEFENDERS OF WILDLIFE V. ZINKE

Interior and the Secretary of Commerce with identifying and 

maintaining a list of endangered and threatened species. 

16 U.S.C. § 1533(a)(1)–(2). Endangered species are those 

“in danger of extinction throughout all or a significant 

portion of its range.” Id. at § 1532(6). Threatened species 

are those “likely to become an endangered species within the 

foreseeable future.” Id. at § 1532(20). The Secretary of the 

Interior is additionally charged with designating “critical 

habitat” for each listed species. Id. at § 1533(a)(3)(A)(i). 

Critical habitat is defined as (a) “specific areas within the 

geographical area occupied by the [endangered] species . . . 

on which are found those physical or biological features 

(I) essential to the conservation of the species and (II) which 

may require special management considerations or 

protection,” id. at § 1532(5)(A)(i), and (b) “specific areas 

outside the geographical area occupied by the species . . .

[that] are essential for the conservation of the species,” id. at 

§ 1532(5)(A)(ii). However, critical habitat generally does 

“not include the entire geographical area which can be 

occupied by the threatened or endangered species.” Id. at 

§ 1532(5)(C).

Section 7(a)(2) of the ESA “affirmatively commands 

each federal agency to ‘insure that any action authorized, 

funded, or carried out’ by the agency ‘is not likely to 

jeopardize the continued existence of any endangered 

species . . . or result in the destruction or adverse 

modification of habitat of such species.’” Or. Nat. Res. 

Council v. Allen, 476 F.3d 1031, 1033 (9th Cir. 2007) 

(quoting 16 U.S.C. § 1536(a)(2)). To comply with Section 

7(a)(2), an agency proposing an action (the action agency) 

must first determine whether the action “may affect” an 

endangered or threatened species or its critical habitat. 

50 C.F.R. § 402.14(a) (2016). If the action agency 

determines that its proposed action “may affect” an 
DEFENDERS OF WILDLIFE V. ZINKE 7

endangered species or its critical habitat, the action agency 

must initiate formal consultation with either the FWS or the 

National Marine Fisheries Service (NMFS), as appropriate 

(collectively, the consulting agency). Id. Under certain 

circumstances, an action agency may bypass formal 

consultation. For example, the ESA’s implementing 

regulations allow for informal consultation, “an optional 

process that includes all discussions, correspondence, etc., 

between [the action agency and the consulting agency], 

designed to assist the [action] agency in determining whether 

formal consultation . . . is required.” Id. at § 402.13(a). “If 

during informal consultation it is determined by the [action] 

agency, with the written concurrence of the [consulting 

agency], that the action is not likely to adversely affect listed 

species or critical habitat, the consultation process is 

terminated, and no further action is necessary.” Id.

But if formal consultation is required, “the consulting 

agency must prepare a biological opinion that advises the 

action agency as to whether the proposed action, alone or 

‘taken together with cumulative effects, is likely to 

jeopardize the continued existence of listed species or result 

in the destruction or adverse modification of critical 

habitat.’” Conservation Cong., 720 F.3d at 1051 (quoting 

50 C.F.R. § 402.14(g)(4)). Jeopardy to the continued 

existence of a listed species (jeopardy) “means to engage in 

an action that reasonably would be expected, directly or 

indirectly, to reduce appreciably the likelihood of both the 

survival and recovery of a listed species in the wild by 

reducing the reproduction, numbers, or distribution of that 

species.” 50 C.F.R. § 402.02. Destruction or adverse 

modification of critical habitat (adverse modification) 

“means a direct or indirect alteration that appreciably 

diminishes the value of critical habitat for both the survival 
8 DEFENDERS OF WILDLIFE V. ZINKE

and recovery of a listed species.” Id. (2014).1 “Such 

alterations include, but are not limited to, alterations 

adversely modifying any of those physical or biological 

features that were the basis for determining the habitat to be 

critical.” Id. In making these determinations, the biological 

opinion “must state a rational connection between the facts 

found and the decision made,” Gifford Pinchot Task Force 

v. U.S. Fish & Wildlife Serv., 378 F.3d 1059, 1065 (9th Cir. 

2004), and also rely on “the best scientific and commercial 

data available.” 16 U.S.C. § 1536(a)(2).

If the consulting agency determines that a proposed 

action is likely to result in jeopardy or adverse modification, 

the consulting agency must suggest “reasonable and prudent 

alternatives, if any” that avoid jeopardy or adverse 

modification. 50 C.F.R. § 402.14(h)(3). If there are no 

alternatives, then any “take” of the listed species resulting 

from the proposed action will violate Section 9 of the ESA, 

which prohibits the taking of any member of an endangered 

or threatened species. Ctr. for Biological Diversity, 698 F.3d 

at 1106–07 (citing 16 U.S.C. § 1538(a)(1)(B)). Violations 

of Section 9 can result in “substantial civil and criminal 

penalties, including imprisonment.” Id. at 1107 (internal 

quotation marks omitted).

If the consulting agency concludes that the proposed 

action is not likely to result in jeopardy or adverse 

modification, but the project nevertheless results in takings 

of a listed species that “result from, but are not the purpose 

of, carrying out” the requested agency action, the consulting 

agency must include an incidental take statement in the 

 1 This definition of adverse modification governed at the time the 

BiOp was issued. For the current governing definition and a discussion 

of the change, see infra Section II.b.
 DEFENDERS OF WILDLIFE V. ZINKE 9 

biological opinion. 50 C.F.R. § 402.02. The incidental take 

statement “(1) specif[ies] the impact of the incidental taking 

on the species; (2) specif[ies] the ‘reasonable and prudent 

measures’ that the FWS considers necessary or appropriate 

to minimize such impact; (3) set[s] forth ‘terms and 

conditions’ with which the action agency must comply to 

implement the reasonable and prudent measures . . . ; and 

(4) specif[ies] the procedures to be used to handle or dispose 

of any animals actually taken.” Or. Nat. Res. Council, 

476 F.3d at 1034 (citing 16 U.S.C. § 1536(b)(4) and 

50 C.F.R. § 402.14(i)). Compliance with the terms of an 

incidental take statement “exempts the action agency from 

the prohibition on takings found in Section 9 of the ESA.” 

Nat’l Wildlife Fed’n v. Nat’l Marine Fisheries Serv., 

524 F.3d 917, 924–25 (9th Cir. 2008) (footnote omitted) 

(citing 16 U.S.C. § 1536(b)(4) and ALCOA v. BPA, 175 F.3d 

1156, 1159 (9th Cir. 1999)). 

The Desert Tortoise

The desert tortoise is a reptile native to the Mojave and 

Sonoran deserts in southern California, southern Nevada, 

Arizona, and the southwestern tip of Utah. In 1990, the FWS 

listed the desert tortoise as “threatened.” See 55 Fed. Reg. 

12,178-01, 12,179-80 (Apr. 2, 1990). In 1994, the FWS 

divided the entire range of the desert tortoise into six 

recovery units to “conserve the genetic, behavioral, 

morphological, and ecological diversity necessary for longterm sustainability of the entire [desert tortoise] population.” 

The FWS then designated a total of 6.4 million acres of land 

within the six recovery units as the desert tortoise’s critical 

habitat. 59 Fed. Reg. 5,820-01, 5,827 (Feb. 8, 1994). One 

of the six recovery units, the Eastern Mojave Recovery Unit, 

is at issue here.
10 DEFENDERS OF WILDLIFE V. ZINKE

The Silver State South Project

In 2008, NextLight Renewable Power, LLC submitted 

right-of-way applications to the BLM for the construction of 

two solar power facilities, Silver State North and Silver State 

South. It proposed to locate both project sites on 

unincorporated public lands in the Ivanpah Valley. 

Although the proposed project sites fell within the Eastern 

Mojave Recovery Unit, both were outside the designated 

critical habitat for the desert tortoise within this recovery 

unit. However, Silver State South would be located within 

a corridor between Silver State North and the Lucy Gray 

Mountains, which is currently the geographical linkage that 

provides “the most reliable potential for continued 

population connectivity [of the desert tortoise] throughout 

the Ivanpah Valley.” Connectivity is the “degree to which 

population growth and vital rates are affected by dispersal” 

and “the flow of genetic material between two populations.” 

Connectivity promotes stability in a species by “providing 

an immigrant subsidy that compensates for low survival or 

birth rates of residents” and “increasing colonization of 

unoccupied” habitat.

In October 2010, the BLM approved the application for 

Silver State North but deferred approval of the application 

for Silver State South. The BLM explained that the deferral 

of Silver State South was in part due to the “higher density 

of [desert] tortoise that reside in that portion of the project 

area,” which “requires additional wildlife consideration and 

potentially further consultation with the [FWS].”

In October 2012, the BLM issued a draft Supplemental 

Environmental Impact Statement (SEIS) that evaluated three 

alternative layouts for Silver State South. In response to the 

SEIS, the Nevada field office of the FWS recommended that 

the BLM reject all three layouts and choose a “No Action” 
DEFENDERS OF WILDLIFE V. ZINKE 11

alternative. The FWS expressed concern over Silver State 

South’s potential impact on habitat fragmentation and 

genetic isolation of the desert tortoise and noted that the 

proposed layouts would reduce the existing width of the 

corridor between Silver State North and the Lucy Gray 

Mountains to .02 miles, .03 miles, or 1 mile. In the 

alternative, the FWS recommended that the BLM create a 

new proposal that would keep the corridor “wide enough to 

accommodate multiple desert tortoise ranges, spanning up to 

several times the desert tortoise lifetime utilization area.” 

The FWS also recommended the adoption of additional 

mitigation measures to offset any reductions in the linkage 

and monitoring studies to track impact on population 

demographics and genetic stability.

On February 11, 2013, the BLM initiated formal 

consultation under the ESA for Silver State South. The 

consultation process among the BLM, the FWS, and Silver 

State Solar Power South, LLC, a wholly owned subsidiary 

of the original applicant for the Silver State South project,

resulted in a new proposal (the BLM-preferred alternative) 

that was authorized by the BLM in 2014. The BLMpreferred alternative reduced the size of the project from 

3,881 acres to 2,427 acres, and left a 3.65 mile long corridor 

between Silver State South and the Lucy Gray Mountains 

with a width ranging from 1.39 to 2 miles. The BLMpreferred alternative also incorporated measures to minimize 

adverse effects on the desert tortoise, such as the 

translocation of desert tortoises found within the project site, 

and measures to offset the loss of the desert tortoise habitat, 

primarily consisting of the Silver State South applicants 

funding the BLM’s conservation activities.

Of particular importance to this case, the Silver State 

South applicants agreed to fund a monitoring program 
12 DEFENDERS OF WILDLIFE V. ZINKE

jointly developed by the U.S. Geological Survey and the 

BLM (the USGS monitoring study) that would track the 

regional desert tortoise populations for changes in 

demographic and genetic stability. The study would monitor 

the effects of Silver State South on connectivity by taking an 

initial set of measurements that would establish baseline 

conditions that could then be compared to subsequent data 

over time and across sites. Changes “that rise to the level of 

significance (alpha = 0.05) would likely indicate changes in 

demographic and genetic stability,” which could require the 

BLM to re-initiate formal consultation under the ESA.

The Biological Opinion

On September 30, 2013, the FWS issued the BiOp, 

which formally reviewed the BLM-preferred alternative. 

The BiOp selected the entire Ivanpah Valley as the “action 

area”2 for Silver State South, because of the “potential 

effects . . . on connectivity for the desert tortoise within the 

entire valley.”

The BiOp first concluded that Silver State South would 

be “not likely to adversely affect the critical habitat of the 

desert tortoise,” because “the proposed actions would not 

occur within the boundaries of critical habitat of the desert 

tortoise or directly or indirectly affect the primary 

constituent elements of critical habitat” (“no adverse 

modification” determination).

The BiOp next concluded that Silver State South was 

unlikely to appreciably diminish the reproduction, numbers, 

 2 “Action area means all areas to be affected directly or indirectly by 

the Federal action and not merely the immediate area involved in the 

action.” 50 C.F.R. § 402.02.
DEFENDERS OF WILDLIFE V. ZINKE 13

or distribution of the desert tortoise in the action area (“no 

jeopardy” determination). The BiOp found no long term 

effects on the reproductive rates of tortoises that live 

adjacent to the project site or of tortoises that would be 

translocated. It estimated that few tortoises would be 

harmed or killed because of the proposed translocation of 

tortoises found in the project site and fencing to be built 

around Silver State South. It also acknowledged that the 

habitat loss of 2,388 acres “will reduce connectivity between 

the southern and northern ends of Ivanpah Valley,” but 

explained that the proposed mitigation measures would 

“offset, to some degree, the decrease in the width of the 

linkage.” The BiOp therefore expressed “uncertain[ty] as to

whether the reduced width of the corridor between the Silver 

State South Project and the Lucy Gray Mountains would 

cause demographic or genetic instability.” But, the BiOp 

reasoned, should Silver State South ultimately degrade 

connectivity, the USGS monitory survey would be able to 

detect any change and “the long generation time [of the 

tortoise] and re-initiation requirements of section 7(a)(2) 

would enable [the BLM] to undertake correction actions on 

the ground to bolster connectivity.”

The BiOp also concluded that Silver State South would 

not appreciably impede the long-term recovery of the desert 

tortoise, but acknowledged that the project was likely to 

reduce connectivity within the Ivanpah Valley, which would 

temporarily impede recovery. However, the BiOp 

concluded that the project was “not likely to appreciably 

diminish the likelihood of recovery” because “at least one 

desert tortoise’s lifetime utilization area would remain in the 

corridor after construction of the product.” In addition,

“[t]his corridor, combined with the increased level of 

management proposed by the [BLM] . . . has the potential to 

increase the density of desert tortoises in the region to a 
14 DEFENDERS OF WILDLIFE V. ZINKE

degree that may mitigate the loss of habitat.” The BiOp 

again noted that the USGS monitoring study would detect 

any changes to connectivity, which would allow for 

imposition of remedial measures.

The BLM Approval of the Right-of-Way for 

Silver State South

In February 2014, the BLM issued a Record of Decision, 

and granted the requested right-of-way for Silver State 

South. The Record of Decision specifically approved the 

BLM-preferred alternative for Silver State South and noted 

that the “reasonable and prudent measures contained in the 

[BiOp] significantly minimize and/or mitigate 

environmental damage and protect resources.” Construction 

of Silver State South has now been completed.

Procedural History

On March 6, 2014, DOW sued the Federal Defendants to 

enjoin construction of Silver State South. Silver State Solar 

Power South, LLC and Silver State South Solar, LLC, 

another subsidiary of the original project applicant, 

subsequently intervened as defendants. The district court 

denied DOW’s request for a preliminary injunction, 

concluding that DOW could not show a likelihood of success 

on the merits of their claim that the BiOp’s “no jeopardy” 

determination was arbitrary or capricious. Defs. of Wildlife 

v. Jewell, No. CV 14-1656-MWF, 2014 WL 1364452, at *14 

(C.D. Cal. Apr. 2, 2014). 

The parties subsequently cross-moved for summary 

judgment. The district court denied DOW’s motion and 

granted summary judgment for the various Defendants. In 

doing so, the district court first concluded that the BiOp’s 

“no adverse modification” determination was neither 
DEFENDERS OF WILDLIFE V. ZINKE 15

arbitrary nor capricious because (1) adverse modification is 

an alteration to a critical habitat’s primary constituent 

elements, and “gene flow” is not a primary constituent 

element of the desert tortoise’s critical habitat, (2) mere 

inclusion of critical habitat in the identified “action area” for 

Silver Lake South is not a finding of adverse modification, 

and (3) adverse effects on connectivity are not modifications 

to critical habitat and should instead be analyzed under the 

jeopardy-to-the-species analysis. The district court next 

concluded that the BiOp’s “no jeopardy” determination was 

neither arbitrary nor capricious, because (1) the BiOp 

permissibly made a “no jeopardy” determination based on 

equivocal evidence that the reduced corridor was unlikely to 

jeopardize the desert tortoise’s recovery, (2) the USGS 

monitoring study was a sufficiently specific and certain 

mitigation measure, and (3) the USGS monitoring study 

provided a sufficiently clear trigger for reinitiating formal 

consultation under Section 7(a)(2) of the ESA. The district 

court therefore concluded that the BiOp fully complied with 

both the ESA and the APA, and that the BLM permissibly 

relied upon the BiOp in authorizing Silver State South. 

DOW timely appealed on May 28, 2015.

STANDARD OF REVIEW

We review de novo a district court’s grant of summary 

judgment. San Luis & Delta-Mendota Water Auth. v. Jewell, 

747 F.3d 581, 601 (9th Cir. 2014).

“Agency decisions under ESA are governed by the 

Administrative Procedure Act, which requires an agency 

action to be upheld unless it is found to be ‘arbitrary, 

capricious, an abuse of discretion, or otherwise not in 

accordance with law.’” Pac. Coast Fed’n of Fishermen’s 

Ass’ns, Inc. v. Nat’l Marine Fisheries Serv., 265 F.3d 1028, 

1034 (9th Cir. 2001) (quoting 5 U.S.C. § 706(2)(A)). An
16 DEFENDERS OF WILDLIFE V. ZINKE

agency action is arbitrary and capricious “only if the agency 

relied on factors Congress did not intend it to consider, 

entirely failed to consider an important aspect of the 

problem, or offered an explanation that runs counter to the 

evidence before the agency or is so implausible that it could 

not be ascribed to a difference in view or the product of 

agency expertise.” Conservation Cong, 720 F.3d at 1054 

(internal quotation marks omitted).

ANALYSIS

Jeopardy Analysis 

DOW first argues that the BiOp’s determination that 

Silver State South would not result in jeopardy to the desert 

tortoise impermissibly relied upon unspecified remedial 

measures. DOW cites the BiOp’s conclusion, which states: 

To summarize, we concluded that the 

proposed actions are not likely to appreciably 

diminish reproduction, numbers, or 

distribution of the desert tortoise in the action 

area, or to appreciably impede long-term 

recovery of the desert tortoise. Integral to 

that conclusion is our expectation that the 

reduction in the width of habitat east of the 

Silver State South Project is either unlikely to 

degrade demographic or genetic stability in 

Ivanpah Valley or that we will be able to 

detect degradation of those values and 

implement remedial actions, if necessary.

(Emphasis added). DOW interprets this second sentence to 

indicate that the BiOp’s “no jeopardy” determination was 

dependent on the ability to detect future demographic or 

genetic degradation and implement remedial measures. 
DEFENDERS OF WILDLIFE V. ZINKE 17

And, because the BiOp did not identify specific remedial 

actions to combat these future effects, DOW argues that 

BiOp’s “no jeopardy” determination was arbitrary and 

capricious.

DOW’s objection to the BiOp’s “no jeopardy” 

determination fails for two reasons. First, the BiOp did not 

rely on mitigation measures to make its “no jeopardy” 

determination. Throughout the BiOp, the FWS expressly 

stated that it was uncertain if the reduced width of the 

corridor between Silver State South and the Lucy Gray 

Mountains would cause genetic or demographic instability. 

This uncertainty reflected the lack of a scientific consensus 

regarding the requisite corridor width necessary to support 

connectivity for the desert tortoise. In the face of such 

uncertainty, the FWS permissibly concluded that the reduced 

width of the corridor would not result in jeopardy. Although 

the ESA requires the FWS to make its determinations with 

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

§ 1533(b)(2), “the ESA accepts agency decisions in the face 

of uncertainty.” Ariz. Cattle Growers’ Ass’n v. Salazar, 606 

F.3d 1160, 1164 (9th Cir. 2010); see also San Luis & DeltaMendota Water Auth., 747 F.3d at 633 (“It is not our job to 

task the FWS with filling the gaps in the scientific evidence. 

We must respect the agency’s judgment even in the face of 

uncertainty.” (internal quotation marks omitted)). “This 

standard does not require that the FWS act only when it can 

justify its decision with absolute confidence.” Ariz. Cattle 

Growers, 606 F.3d at 1164. The FWS therefore permissibly 

concluded that the proposed action would not result in 

jeopardy to the desert tortoise in spite of the uncertainty of 

the effect of Silver State South on the connectivity within the 

corridor.
18 DEFENDERS OF WILDLIFE V. ZINKE

Second, our precedents do not require mitigation 

measures to be identified or guaranteed when the mitigation 

measures themselves may be unnecessary. We have held 

that an action agency may consider the impact of mitigation 

measures on a proposed action only when the measures are 

the result of “specific and binding plans” and show “a clear, 

definite commitment of resources,” Nat’l Wildlife Fed’n,

524 F.3d at 936, but our precedents imposing this 

requirement all involve mitigation measures aimed at 

“certain immediate negative effects,” id.; see also Sierra 

Club v. Marsh, 816 F.2d 1376, 1388 (9th Cir. 1987) 

(requiring the FWS to reinitiate formal consultation after the 

FWS concluded that a highway construction project would 

adversely affect bird habitat and the county’s preservation of 

marshland was “necessary to mitigate” the “effects of the 

project,” but the county subsequently failed to acquire the 

marshland), abrogated on other grounds as recognized in 

Cottonwood Envtl. Law Ctr. v. U.S. Forest Serv., 789 F.3d 

1075, 1088–91 (9th Cir. 2015). Thus, our precedents require 

an agency to identify and guarantee mitigation measures that 

target certain or existing negative effects. However, DOW 

cites no authority for the proposition that an agency must 

similarly identify and guarantee mitigation measures that 

target uncertain future negative effects. As aptly noted by 

the district court, “[t]he FWS cannot be expected to respond 

to data that is not yet available to surmise potential 

mitigation actions that are not needed under the agency’s 

current interpretation of the data.”

Here, although the BiOp repeatedly emphasized that 

monitoring would allow the FWS to detect any future 

genetic or demographic degradation and implement 

responsive mitigation measures, the BiOp ultimately found 

these potential harms to be uncertain. As such, even the 

sentence of the BiOp upon which DOW relies acknowledges 
 DEFENDERS OF WILDLIFE V. ZINKE 19 

that the need for future mitigation measures is similarly 

uncertain, by explaining that the implementation of remedial 

actions will only be done “if necessary.” Because the BiOp 

did not rely upon these potential remedial measures to target 

a certain or existing harm that would be caused by Silver 

State South, the BiOp was not obligated to identify or 

guarantee these future remedial measures. Accordingly, the 

BiOp’s “no jeopardy” determination was neither arbitrary 

nor capricious. 

Adverse Modification Analysis 

The BiOp concluded that Silver State South would be 

“not likely to adversely affect critical habitat of the desert 

tortoise,” because “the proposed actions would not occur

within the boundaries of critical habitat of the desert tortoise 

or directly or indirectly affect the primary constituent 

elements of critical habitat.” The BiOp therefore did not 

analyze whether Silver State South would adversely modify 

the critical habitat within the Ivanpah Valley. DOW 

challenges the failure to do so on two grounds. 

Inclusion of Critical Habitat in the “Action 

Area”

DOW first contends that the BiOp’s inclusion of critical 

habitat within Silver State South’s “action area” expressly 

conceded that there would be an effect on critical habitat, 

which should have obligated the FWS to conduct an adverse 

modification analysis in the BiOp. The ESA’s implementing 

regulations require biological opinions to analyze “effects of 

the [proposed] action on listed species or critical habitat,” 50 

C.F.R. § 402.14(h)(2), and “[e]ffects of the action refers to 

the direct and indirect effects of an action on the species or

critical habitat” within the relevant “action area,” id. at 

§ 402.02. The regulations then define “action area” as “all 
20 DEFENDERS OF WILDLIFE V. ZINKE

areas to be affected directly or indirectly by the Federal 

action and not merely the immediate area involved in the 

action.” Id. The BiOp selected the Ivanpah Valley as the 

“action area” for Silver State South, and DOW notes that the 

Ivanpah Valley Critical Habitat Unit (CHU) is within the 

Ivanpah Valley. DOW insists that the BiOp’s inclusion of 

Ivanpah Valley CHU in the action area is a finding that 

critical habitat would be affected by Silver State South.

We rejected a similar argument in Friends of the Wild 

Swan v. Weber, 767 F.3d 936 (9th Cir. 2014). There, we 

concluded that the consulting agency need not conduct an 

adverse modification analysis in spite of the biological 

opinion’s inclusion of critical habitat within the action area. 

Id. at 950. Because both the consulting and action agencies 

had agreed that the projects at issue were unlikely to affect 

the critical habitat, “[t]his informal consultation satisfied the 

requirements of the ESA and no formal consolation was thus 

required.” Id. (citing 50 C.F.R. § 402.13). Friends of the 

Wild Swan illustrates the proposition that the inclusion of 

critical habitat in a biological opinion’s action area does not 

automatically trigger the duty to conduct an adverse 

modification analysis; the relevant inquiry remains whether 

the proposed action is “likely to adversely affect” critical 

habitat. 50 C.F.R. § 402.14(b)(1); see also id.

§ 402.14(g)(4).

Here, both the BLM and the FWS concluded that Silver 

State South would be unlikely to adversely affect any critical 

habitat through informal consultation. As mentioned above, 

no formal consultation is required if both the action agency 

and the consulting agency determine, the latter in writing, 

through informal consultation that the action is “not likely to 

adversely affect listed species or critical habitat.” Id.

§ 402.13(a). The BLM made this determination in a 
 DEFENDERS OF WILDLIFE V. ZINKE 21 

biological assessment dated February 11, 2013. The FWS 

reached an identical conclusion in the BiOp itself. Because 

the BLM and the FWS were in agreement, the FWS had no 

obligation to conduct an adverse modification analysis 

pursuant to formal consultation in the BiOp. In any event, 

the BiOp also explained that its inclusion of the entire 

Ivanpah Valley in the action area was due to the potential 

effect of Silver State South “on connectivity for the desert 

tortoise within the entire valley,” not any potential effect on 

the Ivanpah Valley CHU.

Reduced Connectivity as an “Adverse 

Modification” of Critical Habitat

Although the construction of Silver State South was not 

to occur on any critical habitat, DOW argues that the BiOp 

was obligated to perform an adverse modification analysis 

because evidence in the record indicated that the 

construction of Silver State South would narrow the corridor 

between two critical habitats, and thus adversely affect the 

connectivity of the desert tortoise. DOW contends that this 

reduction in connectivity constitutes adverse modification of 

critical habitat because it is an impact to the critical habitat’s 

recovery value.

During the period of time in which the BLM, the FWS, 

and Silver State South applicants engaged in the Section 7 

consultation process that resulted in the BiOp, the ESA’s 

implementing regulations defined “destruction or adverse 

modification of critical habitat” as “a direct or indirect 

alteration that appreciably diminishes the value of critical 

habitat for both the survival and recovery of a listed species” 

(the 1986 regulation). 50 C.F.R. § 402.02 (2014). The 1986 

regulation further explained that “[s]uch alterations include, 

but are not limited to, alterations adversely modifying any of 

those physical or biological features that were the basis for 
22 DEFENDERS OF WILDLIFE V. ZINKE

determining the habitat to be critical.” Id. However, on 

February 11, 2016, the FWS and the NMSF published a final 

rule amending the definition of adverse modification (the 

2016 regulation) that became effective on March 14, 2016. 

81 Fed. Reg. 7,214-01, 7,225-26 (Feb. 11, 2016). The 2016 

regulation now defines adverse modification as “a direct or 

indirect alteration that appreciably diminishes the value of 

critical habitat for the conservation of a listed species.” 

50 C.F.R. § 402.02 (2016). And “[s]uch alterations may 

include, but are not limited to, those that alter the physical or 

biological features essential to the conservation of a species 

or that preclude or significantly delay development of such 

features.” Id. This amendment was a direct result of our 

decision in Gifford Pinchot Task Force v. U.S. Fish & 

Wildlife Service, 378 F.3d 1059 (9th Cir. 2004). 81 Fed. 

Reg. 7,214-01, 7,215. There, we found the 1986 regulation 

to be invalid insofar as it limited adverse modifications to 

actions that “appreciably diminish[] the value of critical 

habitat for both the survival and recovery” of habitat. 

Gifford Pinchot Task Force, 378 F.3d at 1069 (quoting 

50 C.F.R. § 402.02). We explained that this definition 

“read[] the ‘recovery’ goal out of the adverse modification 

inquiry” altogether, “[b]ecause it is logical and inevitable 

that a species requires more critical habitat for recovery than 

is necessary for the species survival, the regulation’s 

singular focus becomes ‘survival.’” Id. We emphasized that 

the text of the ESA evinced congressional intent to view 

“conservation,” which incorporates “recovery,” and 

“survival” as “distinct, though complementary, goals, and 

the requirement to preserve critical habitat is designed to 

promote both conservation and survival.” Id. at 1070. We 

therefore concluded that “[w]here Congress in its statutory 

language required ‘or,’ the agency in its regulatory definition 

substituted ‘and.’” Id.
DEFENDERS OF WILDLIFE V. ZINKE 23

The parties each rely on different versions of the 

regulation to argue whether reduced connectivity can 

constitute adverse modification. Defendants first emphasize 

that the plain language of Section 7 of the ESA requires 

agencies to ensure that none of their actions “result in the 

destruction or adverse modification of habitat.” 16 U.S.C. 

§ 1536(a)(2). Defendants argue that the phrase “adverse 

modification of habitat” itself imposes two requirements: 

there must be (1) a “modification of habitat,” which 

Defendants interpret to mean “some change to the habitat 

itself,” that is (2) “adverse.” Second, Defendants insist that 

a change in the desert tortoise’s connectivity is an effect on 

the “species” and not a change to the “habitat.” Third, 

Defendants cite our precedents and other ESA implementing 

regulations that frame adverse modification inquiry as one 

based on alterations to the “primary constituent elements” of 

the critical habitat. See e.g., Butte Envtl. Council v. U.S. 

Army Corps of Eng’rs, 620 F.3d 936, 948 (9th Cir. 2010) 

(characterizing adverse modification as “[a]dverse effects on 

. . . constituent elements or segments of critical habitat” 

(quoting U.S. Fish & Wildlife Serv. & Nat’l Marine 

Fisheries Serv., Endangered Species Consultation 

Handbook: Procedures for Conducting Consultation and 

Conference Activities Under Section 7 of the Endangered 

Species Act 4-43 (1998)); 50 C.F.R. § 17.94 (“All Federal 

agencies must insure that any action authorized, funded, or 

carried out by them is not likely to result in the destruction 

or adverse modification of the constituent elements essential 

to the conservation of the listed species within these defined 

Critical Habitats.”). Critical habitats are comprised of 

primary constituent elements, which are listed in the critical 

habitat designations. 50 C.F.R. § 424.12(b). Defendants 

argue that reducing connectivity would not affect any of the 

desert tortoise’s primary constituent elements, which 

includes “[s]ufficient space to . . . provide for . . . gene 
24 DEFENDERS OF WILDLIFE V. ZINKE

flow,” but not connectivity as a whole. 59 Fed Reg. 5,820, 

5,822. Finally, Defendants contend that the 2016 regulation 

does not alter the requirement that adverse modification 

requires some modification to the habitat itself.

In contrast, DOW argues that any action that adversely 

impacts the “recovery” value of critical habitat can constitute 

an adverse modification. DOW also cites to the language of 

Section 7 of the ESA, but instead argues that the ESA’s use 

of the phrase “result in” indicates “clear congressional intent 

to require FWS to focus on the consequences of federal 

actions.” Next, DOW contends that Defendants’ 

interpretation of adverse modification cannot be squared 

with the FWS’s interpretation of adverse modification as 

embodied by the 2016 regulation. First, DOW argues that 

the 2016 regulation’s definition of adverse modification as 

an alteration “that appreciably diminishes the value of 

critical habitat for the conservation of a listed species” 

supports DOW’s argument that the adverse modification 

inquiry must focus on the impact of the proposed agency’s 

action on critical habitat’s recovery value as opposed to 

whether there was an alteration to the habitat itself. Second, 

DOW argues that the 2016 regulation’s interpretation of the 

phrase “may include, but not limited to” supports a broad 

conception of what constitutes an alteration of critical 

habitat. In the supplementary information accompanying the 

publication of the 2016 regulation (2016 regulation 

commentary), the FWS and the NMFS explained that this 

phrase “emphasizes that the types of direct or indirect 

alterations that appreciably diminish the value of critical 

habitat for listed species include not only those that affect 

physical or biological features, but also those that affect the 

value of critical habitat itself.” 81 Fed. Reg. 7,214, 7,219. 

This phrase therefore encapsulates “impacts to an area of 

critical habitat itself that are not impacts to features,” such 
DEFENDERS OF WILDLIFE V. ZINKE 25

as “those that would impede access to or the use of the 

habitat.” Id.

We agree with Defendants that the plain language of the 

ESA requires that an adverse modification of critical habitat 

consists of two elements: (1) a “modification” of the habitat 

that is (2) “adverse.” 16 U.S.C. § 1536(a)(2). Both the 1986 

and 2016 definitions reflect that understanding by defining 

adverse modification as a “direct or indirect alteration” that 

“appreciably diminishes the value of the critical habitat.” 

50 C.F.R. § 402.02 (2014) (emphasis added); 50 C.F.R. 

§ 402.02 (2016) (same). This interpretation of adverse 

modification is further confirmed by the 2016 regulation 

commentary, which describes the adverse modification 

analysis as follows:

[The FWS] will generally conclude that a 

Federal action is likely to “destroy or 

adversely modify” designated critical habitat 

if the action results in an alteration of the 

quantity or quality of the essential physical or 

biological features of designated critical 

habitat, or that precludes or significantly 

delays the capacity of that habitat to develop 

those features over time, and if the effect of 

the alteration is to appreciably diminish the 

value of critical habitat for the conservation 

of the species.

81 Fed. Reg. 7214-01, 7216 (emphasis added). DOW’s 

interpretation of “adverse modification” focuses solely on 

the effect of the proposed agency action, and thus improperly 

reads the “alteration” requirement out of the ESA’s 

implementing regulations altogether. Furthermore, DOW’s 

reliance on the 2016 regulation commentary’s explanation 
26 DEFENDERS OF WILDLIFE V. ZINKE

of the phrase “may include, but are not limited to” is 

misplaced. This phrase merely clarifies the types of impacts 

on the critical habitat that can result in adverse modification; 

it does not speak to the threshold requirement that there must 

be an alteration to the critical habitat that creates these 

impacts to begin with. See 81 Fed. Reg. 7,214, 7,219. 

With this proper understanding of “adverse 

modification” in mind, we conclude that reduced 

connectivity resulting from the narrowing of the corridor 

between Silver State South and the Lucy Gray Mountains 

cannot constitute adverse modification because the 

construction of Silver State South would not have resulted in 

any alteration to the critical habitat of the desert tortoise. It 

is undisputed that the corridor itself is not critical habitat and 

the construction of Silver State South would not have taken 

place on any critical habitat within the Ivanpah Valley. Nor 

can reduced connectivity itself serve as the alteration; 

reduced connectivity can lead to a change in the desert 

tortoise’s genetic health, which is an alteration to the species, 

not its critical habitat. Accordingly, the BiOp’s 

determination that Silver State South was “not likely to 

adversely affect the critical habitat of the desert tortoise,” 

which permitted the FWS to forego an adverse modification 

analysis, was neither arbitrary nor capricious.

Inconsistent Positions in the BiOp

The FWS’s SEIS Comments

DOW next contends that the BiOp was arbitrary and 

capricious because it failed to address the FWS Nevada field 

office’s comments on the BLM’s draft SEIS pertaining to 

adverse impacts on recovery, connectivity of critical habitat, 

and recommended corridor-width. DOW notes that the 

FWS’s comments on the SEIS specifically recommended 
DEFENDERS OF WILDLIFE V. ZINKE 27

that the corridor between Silver State South and the Lucy 

Gray Mountains “should be wide enough to accommodate 

multiple desert tortoise ranges, spanning up to several times 

the desert tortoise lifetime utilization area.” DOW argues 

that because the FWS also authored the BiOp, which 

permitted the corridor’s narrowest point to be slightly less 

than a single lifetime utilization area, the FWS was obligated 

to address this inconsistency in the BiOp.

“Agencies are entitled to change their minds.” Butte 

Envtl. Council, 620 F.3d at 946. Thus, “the fact that a 

preliminary determination by a local agency representative 

is later overruled at a higher level within the agency does not 

render the decisionmaking process arbitrary and capricious.” 

Nat’l Ass’n of Home Builders v. Defs. of Wildlife, 551 U.S. 

644, 659 (2007); see also Friends of the Earth v. Hintz, 

800 F.2d 822, 834 (9th Cir. 1986) (finding that agency’s 

approval of a permit despite earlier criticism because “[the 

agency’s] ultimate decision was not a reversal but simply the 

culmination of over a year and a half of investigations, 

meetings, and reports”). However, an agency also “must 

examine the relevant data and articulate a satisfactory 

explanation for its action including a rational connection 

between the facts found and the choice made.” Humane 

Soc’y of U.S. v. Locke, 626 F.3d 1040, 1051 (9th Cir. 2010) 

(emphases and internal quotation marks omitted). Under 

certain circumstances, an agency’s prior factual findings or 

conclusions may be “relevant data” such that an agency must 

“articulate a satisfactory explanation” when it changes its 

mind. See id.

Humane Society of the United States v. Locke illustrates 

this principle. There, we held that the NMFS did not 

adequately explain its finding that a sea lion predation rate 

of 1 percent would have a significant negative impact on the 
28 DEFENDERS OF WILDLIFE V. ZINKE

decline or recovery of salmon “given earlier factual findings 

by NMFS that fisheries that cause similar or greater 

mortality among [the salmon population] are not having 

significant negative impacts.” Id. at 1048. We noted that 

the fishery environmental assessments were “in apparent 

conflict with NMFS’s finding in this case . . . yet the agency 

has not offered a rationale to explain the disparate findings.” 

Id. at 1049. We acknowledged that agencies do not have a 

“duty to identify and any potential tensions between current 

and earlier factual determinations in marginally related 

administrative actions,” but explained that the impact of 

fisheries compared to that of sea lion predation “ha[d] 

occupied the center of this controversy from the start.” Id.

at 1051. The prior fishery environmental assessments were 

therefore “relevant data” which required a “satisfactory 

explanation.” Id.

Locke is distinguishable from the circumstances here in 

two ways. First, the FWS comments on the SEIS did not 

make any factual or scientific findings. Although the FWS 

recommended that any alternative plan preserve a corridor 

between Silver State South and the Lucy Gray Mounts 

“spanning up to several times the desert tortoise lifetime 

utilization area,” the FWS did not conclude that anything 

less would affirmatively result in a loss of connectivity, 

jeopardy, or adverse modification. The FWS comments on 

the SEIS therefore made no findings with respect to Silver 

State South, let alone any “[d]ivergent” findings that 

required a response in the BiOp. Id. at 1049. Second, the 

SEIS (and by extension, the FWS’s comments on the SEIS) 

evaluated three proposed plans for Silver State South that 

differed significantly from the BLM-preferred alternative 

analyzed in the BiOp. The BLM-preferred alternative 

reduced the size of the project from 3,881 acres to 2,427 

acres, increased the width of the corridor between Silver 
 DEFENDERS OF WILDLIFE V. ZINKE 29 

State South and the Lucy Gray Mountains at its narrowest 

point from 100 feet to 1.39 miles (with the corridor 

maintaining an average width of 1.4 miles), and also 

incorporated mitigation measures recommended by the FWS 

in their comments on the SEIS to minimize adverse effects 

to the desert tortoise and offset the loss of desert tortoise 

habitat. Thus, even if the FWS’s comments on the SEIS 

were construed to have made factual or scientific findings, 

they would not be inconsistent with the FWS’s conclusions 

regarding Silver State South in the BiOp because the SEIS 

and the BiOp evaluated substantially different plans. 

Accordingly, the BiOp’s failure to address the FWS 

comments to the SEIS was not arbitrary or capricious.

Edge Effects

DOW additionally contends that the BiOp contained an 

internal inconsistency regarding the necessary width of the 

corridor: The BiOp recognized that the corridor “would 

need to be at least 1.4 miles wide to accommodate the width 

of a single desert tortoise’s lifetime utilization area,” and 

subsequently acknowledged that because of edge effects 

“the effective width of the corridor to the east of the project 

site is likely less than the measured distance,” but never 

reconciled these two findings. DOW argues that the BiOp’s

failure to quantify the extent of the edge effects or make an 

express finding that edge effects would not be significant to 

this corridor was arbitrary and capricious.

As an initial matter, DOW misconstrues the BiOp as 

concluding that a corridor width of at least 1.4 miles is 

necessary to maintain connectivity in the Ivanpah Valley. 

The BiOp acknowledged that the 1.4 miles estimation 

“provides a means for characterizing the potential minimum 

width of a linkage” required to maintain connectivity, but 

explained that “the actual linkage-width needed will be 
30 DEFENDERS OF WILDLIFE V. ZINKE

highly dependent on the actual site-specific configuration 

and size of desert tortoise home ranges in that area, the 

terrain within the linkage, and the degree to which threats, 

other constrictions, and edge effect will disrupt the linkage.” 

That edge effects may have reduced the width of the corridor 

below 1.4 miles at a single point thus does not create an 

internal inconsistency with the BiOp’s conclusion that the 

corridor width of the approved plan for Silver State South 

would not disrupt the connectivity of the corridor.

Furthermore, the record supports the BiOp’s conclusion 

that edge effects created by Silver State South were unlikely 

to be significant because the “edge effects of a solar plant 

likely extend less into adjacent habitat . . . and [] edge effects 

likely do not emanate from the Lucy Gray Mountains.” 

Although the BiOp’s explanation of this issue is conclusory, 

there is sufficient evidence in the record from we can 

“discern [the FWS’s] reasoning.” San Luis & DeltaMendota Water Auth., 747 F.3d at 604–06 (even an 

“unpolished” or “largely unintelligible” biological opinion 

should be upheld if it is “adequately supported by the record” 

and the court can “discern the agency’s reasoning”). The

record included evidence that desert tortoises were 

burrowing near Silver State North and other existing solar 

projects in the Ivanpah Valley, which corroborates the 

BiOp’s explanation that solar plants result in minimal edge 

effects. The mitigation measures incorporated by the BiOp 

also included measures to minimize edge effects, such as the 

use of “[a]uthorized biologists or desert tortoise monitors 

[to] flag all desert tortoise burrows for avoidance in areas 

adjacent to work areas.” Because we can discern the BiOp’s 

reasoning in concluding that Silver State South would not 

have significant edge effects and the record supports the 

BiOp’s conclusion, the BiOp’s consideration of Silver State 

South’s edge effects was not arbitrary or capricious.
 DEFENDERS OF WILDLIFE V. ZINKE 31 

Trigger for Reinitiation of Formal Consultation 

Lastly, DOW alleges that the BiOp established an 

impermissibly vague trigger for reinitiating formal 

consultation over Silver State South. DOW contends that 

reinitiation triggers must provide “clear criteria” that do not 

give “unfettered discretion” to federal agencies. Although 

the BiOp explained that the FWS would reinitiate formal 

consultation with the BLM if the USGS monitoring survey 

found “changes in demographic and genetic stability [that] 

are related to the Silver State South,” DOW claims that this 

is insufficient because the BiOp does not identify criteria for 

determining whether changes are “related” to Silver State 

South.

We disagree. The ESA’s implementing regulations 

require an action agency to reinitiate formal consultation 

with the consulting agency when “new information reveals 

effects of the action that may affect listed species or critical 

habitat in a manner or to an extent not previously 

considered” (the “new information” reinitation trigger). 

50 C.F.R. § 402.16(b). Neither the ESA nor its 

implementing regulations require the action agency to 

identify ex-ante standards for determining whether 

information is “new” or explaining how “new information” 

will be evaluated.3 In the absence of such authority, the 

 3 The cases that DOW cites for the proposition that reinitiation 

triggers must provide “clear standard[s]” involve reinitiation in the 

“incidental take” context. E.g., Ariz. Cattle Growers, 273 F.3d at 1249–

51. Incidental take statements must “set forth a ‘trigger’ that, when 

reached, results in an unacceptable level of incidental take, invalidating 

the safe harbor provision [of the ESA], and requiring the parties to reinitiate consultation.” Id. at 1249. The requirement that an “incidental 

take” trigger provide clear standards for determining when it has been 

met thus reflects a consequence that is not implicated by the “new 
32 DEFENDERS OF WILDLIFE V. ZINKE

BLM instead exceeded its obligations under the ESA by 

explaining how it would determine when results from the 

USGS monitoring survey would require reinitiation of 

formal consultation. 

Moreover, the BiOp provided clear criteria for 

determining whether any future demographic or genetic 

changes identified by the USGS monitoring survey are 

“related” to Silver State South. The USGS monitoring 

survey will first conduct initial sampling to establish 

baseline conditions from different monitoring plots and will 

then compare this information to subsequent data over time 

and across plots. The BiOp also explained that changes “that 

rise to the level of significance (alpha = 0.05) would likely 

indicate changes in demographic and genetic stability,” 

which would then constitute new information if related to 

Silver State South. The BiOp therefore does not rely on an 

impermissibly vague “new information” reinitiation trigger.

The BLM’s Reliance on the BiOp

Because the BiOp was neither legally nor factually 

flawed, the BLM permissibly relied upon the BiOp in 

approving of the right-of-way for Silver State South. See 

Pyramid Lake Paiute Tribe of Indians v. U.S. Dep’t of Navy, 

898 F.2d 1410, 1415–16 (9th Cir. 1990). 

 

information” trigger: The “new information” trigger merely requires 

reinitiation of formal consultation, while the “incidental take” trigger 

requires not only reinitiation of formal consultation, but also revokes an 

action agency’s or project applicant’s immunity from penalties under 

Section 9 of the ESA. See id. To the extent that DOW asks us to import 

the “clear standard” requirement from “incidental take” triggers into the 

“new information” trigger context, we decline to do so because of this 

substantive difference.
DEFENDERS OF WILDLIFE V. ZINKE 33

CONCLUSION

For the foregoing reasons, the district court’s grant of 

summary judgment to the Defendants is AFFIRMED. 

Plaintiff shall bear costs on appeal. Fed. R. App. P. 39(a)(2).