American Wild Horse Campaign v. David Bernhardt ( 2020 )


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  •                        FOR PUBLICATION
    UNITED STATES COURT OF APPEALS
    FOR THE NINTH CIRCUIT
    AMERICAN WILD HORSE                            No. 18-17403
    CAMPAIGN; KIMERLEE
    CURYL,                                          D.C. No.
    Plaintiffs-Appellants,             3:18-cv-00059-LRH-
    CBC
    v.
    DAVID BERNHARDT,                                 OPINION
    Secretary of the Department
    of the Interior; MICHAEL D.
    NEDD; JILL C. SILVEY,
    Defendants-Appellees.
    Appeal from the United States District Court
    for the District of Nevada
    Larry R. Hicks, District Judge, Presiding
    Argued and Submitted April 29, 2020
    San Francisco, California
    Filed July 2, 2020
    Before: Ronald Lee Gilman,* Susan P. Graber,
    and Daniel P. Collins, Circuit Judges.
    Opinion by Judge Graber
    *
    The Honorable Ronald Lee Gilman, United States Circuit Judge for
    the U.S. Court of Appeals for the Sixth Circuit, sitting by designation.
    2        AM. WILD HORSE CAMPAIGN V. BERNHARDT
    SUMMARY**
    Wild Horses
    The panel affirmed the district court’s summary judgment
    in favor of federal defendants in an action alleging that the
    Bureau of Land Management (“BLM”)’s “geld and release”
    plan for wild horses violated the National Environmental
    Policy Act (“NEPA”), the Administrative Procedure Act, and
    the Wild Free-Roaming Horses and Burros Act.
    BLM developed a Gather Plan to address an excess of
    wild horses. In 2017, BLM determined that there was an
    overpopulation of wild horses in northeastern Nevada. It
    developed a plan to restore ecological balance by adjusting
    the sex ratio of the population, administering fertility control
    treatments to mares, and gelding and releasing back to the
    range some male horses.
    The panel held that BLM did not act arbitrarily or
    capriciously when it chose to geld and release some of the
    male horses that would otherwise be permanently removed.
    The panel rejected plaintiffs’ arguments challenging BLM’s
    actions and decisions.
    Plaintiffs argued that BLM must prepare an
    environmental impact statement (“EIS”) for its Gather Plan
    because five of NEPA’s intensity factors demonstrated that
    gelding and release would have significant effects on the
    environment. First, an agency must prepare an EIS when its
    **
    This summary constitutes no part of the opinion of the court. It has
    been prepared by court staff for the convenience of the reader.
    AM. WILD HORSE CAMPAIGN V. BERNHARDT                  3
    action will have “highly uncertain effects” on the
    environment. The panel held that BLM’s plan to geld and
    release male horses to the range did not meet that threshold.
    The panel held that BLM used the existing evidence to assess
    the level of uncertainty and made reasonable predictions
    based on prior data to conclude that there would be no
    significant environmental impact. Second, the panel held that
    the effects of the Gather Plan were not “highly controversial.”
    Third, the panel held that the Gather Plan did not exhibit
    “unique characteristics;” and BLM’s determination that the
    gather area was not in close “proximity to historic or cultural
    resources” was not arbitrary or capricious. Fourth, the panel
    held that the Gather Plan did not establish a “precedent” for
    future actions where the plan did not establish gelding as an
    accepted population management tool, nor was it the first
    instance of BLM’s releasing geldings to the range. Fifth, the
    panel held that because BLM followed the mandates of the
    Wild Free-Roaming Horses and Burros Act, its decision to
    geld and release did not “threaten a violation of federal law.”
    The panel concluded that BLM permissibly determined that
    the intensity factors did not show that the Gather Plan would
    have a significant effect on the environment, and BLM
    permissibly concluded that preparation of an EIS was not
    required.
    Plaintiffs argued that BLM acted arbitrarily and
    capriciously because it did not address a Gelding Study, did
    not consider the expert opinions that plaintiffs highlighted in
    their public comments, and did not consider adequately a
    National Academy of Sciences (“NAS”) Report on the wild-
    horses program. First, the panel held that BLM met NEPA’s
    “hard look” standard when it considered and addressed the
    relevant factor that the Gelding Study raised and explained
    why additional information was not available. Second, the
    4      AM. WILD HORSE CAMPAIGN V. BERNHARDT
    panel held that The Wild Free-Roaming Horses and Burros
    Act did not require BLM to discuss explicitly all expert
    opinions submitted during the public-comment period. Third,
    the panel held that by addressing the concerns and factors that
    the NAS Report raised, BLM complied with the Wild Free-
    Roaming Horses and Burros Act’s requirement that BLM
    “consult” the NAS to make determinations about how
    appropriate management levels should be achieved.
    COUNSEL
    William N. Lawton (argued), Katherine A. Meyer, and
    William S. Eubanks II, Eubanks & Associates LLC,
    Washington, D.C., for Plaintiffs-Appellants.
    Anna T. Katselas (argued), Devon Lea Flanagan, Daniela A.
    Arregui, Holly A. Vance, Andrea L. Berlowe, and Mark R.
    Haag, Attorneys; Eric Grant, Deputy Assistant Attorney
    General; Jeffrey Bossert Clark, Assistant Attorney General;
    Environment and Natural Resources Division, United States
    Department of Justice, Washington, D.C.; Nancy Zahedi,
    Assistant Regional Solicitor, Pacific Southwest Region,
    United States Bureau of Land Management, United States
    Department of the Interior, Sacramento, California; for
    Defendants-Appellees.
    AM. WILD HORSE CAMPAIGN V. BERNHARDT                  5
    OPINION
    GRABER, Circuit Judge:
    Public lands in the American West are home to thousands
    of wild, free-roaming horses. Congress tasked Defendants,
    the Secretary of the Department of the Interior and officials
    from the Bureau of Land Management (“BLM”), with
    preserving these “living symbols of the historic and pioneer
    spirit of the West,” while also balancing the needs of other
    wildlife and livestock that depend on the resources of public
    lands. 16 U.S.C. § 1331. When wild horses become too
    numerous for the land to support, Congress has mandated that
    BLM remove excess horses until it reestablishes ecological
    balance.
    Id. § 1333.
    In 2017, BLM determined that there was an
    overpopulation of wild horses in northeastern Nevada, and it
    developed a plan to restore ecological balance in the region.
    In an effort to remove as few horses as possible, BLM plans
    to adjust the sex ratio of the population, administer fertility
    control treatments to mares, and geld and release back to the
    range some male horses.
    Plaintiffs American Wild Horse Campaign and Kimerlee
    Curyl objected to the “geld and release” component of the
    plan and brought claims that BLM had violated the National
    Environmental Policy Act (“NEPA”), the Administrative
    Procedure Act, and the Wild Free-Roaming Horses and
    Burros Act. We hold that BLM did not act arbitrarily and
    capriciously and, accordingly, we affirm the district court’s
    grant of summary judgment to Defendants.
    6      AM. WILD HORSE CAMPAIGN V. BERNHARDT
    BACKGROUND
    A. Statutory and Historical Background
    Congress enacted the Wild Free-Roaming Horses and
    Burros Act (“the Act”) in 1971, when wild horses were “fast
    disappearing from the American scene.” 16 U.S.C. § 1331.
    The Act extended federal protection to wild horses and
    empowered BLM to manage horses roaming public ranges as
    part of its management of public lands. But within only a few
    years, the Act proved so successful at replenishing the
    population of wild horses that “action [was] needed to
    prevent [the] program from exceeding its goals and causing
    animal habitat destruction.” H.R. Rep. No. 95-1122, 95th
    Cong., 2d Sess. at 23 (1978).
    In 1978, Congress amended the Act to increase BLM’s
    authority to manage and remove excess horses from public
    lands “to achieve and maintain a thriving natural ecological
    balance.” 16 U.S.C. § 1333(a). The main purpose of the
    amendments was “to cut back on the protection the Act
    affords wild horses, and to reemphasize other uses of the
    natural resources wild horses consume.” Am. Horse
    Protection Ass’n v. Watt, 
    694 F.2d 1310
    , 1316 (9th Cir.
    1982).
    The amended Act directs the agency to maintain an
    inventory of wild horses on public lands so that it can
    determine whether “an overpopulation exists on a given area”
    and whether “action is necessary to remove excess animals.”
    16 U.S.C. § 1333(b)(2). If BLM makes such a finding, the
    agency “shall immediately remove excess animals from the
    range so as to achieve appropriate management levels.”
    Id. Removals must
    continue “until all excess animals have been
    AM. WILD HORSE CAMPAIGN V. BERNHARDT                   7
    removed so as to restore a thriving natural ecological balance
    to the range, and protect the range from the deterioration
    associated with overpopulation.”
    Id. Although BLM
    must
    remove excess horses when it faces an overpopulation, the
    Act also grants BLM the authority to use other population
    control methods, such as sterilization and natural controls, to
    avoid overpopulation.
    Id. § 1333(b)(1);
    see In Def. of
    Animals v. U.S. Dep’t of Interior, 
    751 F.3d 1054
    , 1065 &
    n.16 (9th Cir. 2014) (noting that BLM has broad discretion in
    removing excess animals). In deciding on appropriate
    measures, BLM must consult with state wildlife agencies,
    “individuals independent of Federal and State government as
    have been recommended by the National Academy of
    Sciences,” and others that BLM determines have “scientific
    expertise and special knowledge.” 16 U.S.C. § 1333(b)(1).
    And “management activities shall be at the minimal feasible
    level.”
    Id. § 1333(a).
    In recent years, BLM regularly has had to remove, or
    “gather,” horses from public lands to keep the population
    within the appropriate management levels and to avoid the
    degradation of rangeland resources and the suffering of wild
    horses due to a lack of water and forage. Although the Act
    allows excess horses to be adopted or euthanized, 16 U.S.C.
    § 1333(b)(2), adoption demand is insufficient to achieve
    population control, and Congress effectively has prohibited
    BLM from euthanizing healthy animals by prohibiting the
    authorization of funds to do so. In Def. of 
    Animals, 751 F.3d at 1060
    n.6. Instead, BLM keeps removed horses in long-
    term holding facilities for the remainder of their natural lives.
    About a decade ago, to assist it in improving the wild-
    horses program, BLM commissioned a report from the
    National Academy of Sciences (“NAS Report”) “to provide
    8       AM. WILD HORSE CAMPAIGN V. BERNHARDT
    BLM with a scientific evaluation of the program’s pressing
    challenges.” The report, issued in 2013, evaluated various
    methods of population control. It recommended that BLM
    consider “changes in expression of sexual and social
    behavior” when deciding whether to sterilize horses and
    noted that the “ideal method would not eliminate sexual
    behavior or change social structure substantially.” The report
    concluded that “the methods judged most promising for
    application to free-ranging horses or burros are PZP vaccines,
    GonaCon vaccine,1 and chemical vasectomy.” It noted,
    however, that “testing [of chemical vasectomy] in captive
    horses would be needed before widespread application in the
    field.” As for gelding some males in a herd, the report
    concluded that the effects on reproduction and behavior
    “could not be predicted at the time [the] report was prepared.”
    The report stated that it was not clear how gelding “would be
    better than [surgical] vasectomy, which does not affect
    testosterone or male-type behaviors,” but the report
    recognized that there are some risks to herds associated with
    surgical vasectomy as well.
    To gain a better understanding of gelding as a population-
    control method and of its effects on herd behavior, BLM
    began a five-year study in 2016 (“Gelding Study”). The
    Gelding Study, conducted as part of a gather plan
    implemented in Utah, will evaluate whether gelding is “an
    effective approach to slowing the annual population growth
    rate,” the effects “of maintaining a population of gelded
    males on the behavior and spatial ecology of the overall
    population,” and the “health and short-term survival” of the
    1
    PZP and GonaCon are immune-contraceptive vaccines. PZP
    vaccines are administered to mares; GonaCon vaccines can be
    administered to either male or female horses.
    AM. WILD HORSE CAMPAIGN V. BERNHARDT                 9
    geldings. This is the first study that has examined
    specifically “the effect of gelding on the behavior of free-
    roaming wild horses” and the way in which geldings interact
    with intact wild stallions. Data from the study will not be
    analyzed until October 2020 at the earliest.
    B. The Present Controversy
    The Antelope and Triple B Complexes comprise about
    2.8 million acres of public lands in northeastern Nevada and
    are home to thousands of wild horses. More than a decade
    ago, BLM established that those areas could sustain a total of
    between 899 to 1,678 wild horses. In 2017, based on a
    current inventory of the lands, BLM determined that the
    Complexes contained an excess population of about 8,600
    wild horses and that action was necessary to remove them.
    Once BLM made that determination, the Act required BLM
    to “immediately remove excess animals.” 16 U.S.C.
    § 1333(b)(2).
    BLM developed the Antelope and Triple B Complexes
    Gather Plan (“Gather Plan”) to address the excess, while also
    keeping its management activities to “the minimal feasible
    level.” Under the Gather Plan, BLM will remove the excess
    wild horses over a ten-year period. Horses will be gathered
    in phases as necessary to achieve a core breeding population
    at the low range of the appropriate management level. The
    plan also calls for adjusting sex ratios and administering
    fertility-control treatments to mares in order to slow
    population growth rates and increase intervals between
    gathers.
    In an effort to reduce the number of horses that need to be
    removed permanently from public lands and kept in long-
    10     AM. WILD HORSE CAMPAIGN V. BERNHARDT
    term holding facilities, BLM will geld some male horses and
    release them back onto the range “where they can engage in
    free-roaming behaviors.” By doing so, BLM can reduce the
    breeding population to the low end of the appropriate
    management level, but keep the total population of horses at
    mid-range. The primary purpose of the gelding component
    is not to slow population growth, but to allow more horses to
    remain free-roaming than otherwise would be possible.
    Gelding horses is a centuries-old practice. It has been
    studied extensively and is a routine procedure. It also is one
    of the few permanent fertility-control options, resulting in
    fewer “handling occasions” compared to other impermanent
    methods. The only unknown aspects of gelding—as
    identified in the NAS Report and acknowledged by BLM in
    the Gelding Study—concern how useful it proves to be as a
    population-control method and how wild horses will respond
    when geldings are released back to the range.
    In 2017, BLM issued a preliminary environmental
    assessment of the Gather Plan. 40 C.F.R. § 1508.9. BLM
    received almost 5,000 public comments. Public comments
    notified BLM of the concerns of experts on wild-horse
    behavior about the negative effects of gelding wild horses. In
    the final environmental assessment, BLM responded to those
    comments and explained that the experts’ opinions were
    speculative because none of them had conducted a study on
    the topic. BLM concluded that the Gather Plan would not
    significantly affect the human environment and, thus, that
    BLM was not required to prepare an environmental impact
    statement (“EIS”). In December 2017, BLM issued a finding
    of no significant impact.
    AM. WILD HORSE CAMPAIGN V. BERNHARDT                 11
    In this action, Plaintiffs challenge the “geld and release”
    portion of the Gather Plan. Plaintiffs do not deny that there
    are too many wild horses in the Complexes, that BLM is
    required to address that overpopulation, that removal of some
    horses from the range is appropriate, or that BLM established
    appropriate management levels of wild horses for the
    Complexes. Plaintiffs challenge only BLM’s choice to geld
    and release some of the male horses that would otherwise be
    permanently removed, arguing that the agency acted
    arbitrarily and capriciously. The district court granted
    summary judgment to Defendants on all claims. Plaintiffs
    timely appeal.
    STANDARDS OF REVIEW
    We review de novo a district court’s grant of summary
    judgment. McGinest v. GTE Serv. Corp., 
    360 F.3d 1103
    ,
    1112 (9th Cir. 2004).
    We review agency decisions that allegedly violate NEPA
    under the Administrative Procedure Act, and we set aside
    those decisions only if they are “arbitrary, capricious, an
    abuse of discretion, or otherwise not in accordance with law.”
    Native Ecosystems Council v. U.S. Forest Serv., 
    428 F.3d 1233
    , 1238 (9th Cir. 2005) (quoting 5 U.S.C. § 706(2)(A)).
    In reviewing an agency’s decision not to prepare an EIS,
    we “employ an arbitrary and capricious standard that requires
    us to determine whether the agency has taken a ‘hard look’ at
    the consequences of its actions, based [its decision] on a
    consideration of the relevant factors, and provided a
    convincing statement of reasons to explain why a project’s
    impacts are insignificant.” Envtl. Prot. Info. Ctr. v. U.S.
    12      AM. WILD HORSE CAMPAIGN V. BERNHARDT
    Forest Serv. (EPIC), 
    451 F.3d 1005
    , 1009 (9th Cir. 2006)
    (alteration in original) (internal quotation marks omitted).
    DISCUSSION
    Plaintiffs argue that BLM must prepare an EIS for the
    Gather Plan because five of NEPA’s intensity factors
    demonstrate that gelding and release would have significant
    effects on the environment. Plaintiffs also argue that BLM
    acted arbitrarily and capriciously because it authorized
    gelding and release without considering all the relevant
    evidence.
    A. Intensity Factors
    NEPA requires agencies to prepare an EIS for “major
    Federal actions significantly affecting the quality of the
    human environment.” 42 U.S.C. § 4332(c). To determine
    whether an action will have significant effects, agencies may
    prepare an environmental assessment that “[b]riefly
    provide[s] sufficient evidence and analysis for determining
    whether to prepare an [EIS].” 40 C.F.R. § 1508.9(a)(1). An
    EIS is required if that process raises “substantial questions”
    about whether an agency action will have a significant effect.
    Blue Mountains Biodiversity Project v. Blackwood, 
    161 F.3d 1208
    , 1212 (9th Cir. 1998). If the agency determines that an
    EIS is unnecessary, it issues a finding of no significant
    impact, which “briefly present[s] the reasons why an action
    . . . will not have a significant effect on the human
    environment.” 40 C.F.R. § 1508.13.
    To determine whether an action “significantly” affects the
    environment, agencies must consider both the “context” and
    “intensity” of the possible effects. 40 C.F.R. § 1508.27.
    AM. WILD HORSE CAMPAIGN V. BERNHARDT                  13
    “Intensity” refers to the “severity of impact,” and NEPA
    regulations include ten intensity factors that agencies must
    consider.
    Id. An action
    may be, but is not necessarily,
    “significant” if any one of those factors is met. Ctr. for
    Biological Diversity v. Nat’l Highway Traffic Safety Admin.,
    
    538 F.3d 1172
    , 1220 (9th Cir. 2008).
    Plaintiffs argue that five intensity factors demonstrate that
    the Gather Plan may have a significant impact: (1) the Plan
    has highly uncertain effects; (2) the Plan has highly
    controversial effects; (3) the area has unique characteristics;
    (4) the decision establishes a precedent; and (5) the decision
    threatens a violation of the Wild Free-Roaming Horses and
    Burros Act. 40 C.F.R. § 1508.27(b)(3), (4), (5), (6), & (10).
    We disagree.
    1. Highly Uncertain Effects
    When the possible effects of an agency’s action are so
    “highly uncertain” that they raise “substantial questions”
    about whether the action will have a significant impact on the
    environment, the agency must prepare an EIS. 40 C.F.R.
    § 1508.27(b)(5); Blue 
    Mountains, 161 F.3d at 1212
    . NEPA
    “regulations do not anticipate the need for an EIS anytime
    there is some uncertainty, but only if the effects of the project
    are ‘highly’ uncertain.” Ctr. for Biological Diversity v.
    Kempthorne, 
    588 F.3d 701
    , 712 (9th Cir. 2009) (internal
    quotation marks omitted).
    BLM’s plan to geld and release male horses to the range
    does not meet that threshold. Gelding horses is not a new
    practice, and its effects are well understood.          The
    environmental assessment thoroughly reviewed the research
    on the surgical procedure, on the effects of gelding on
    14     AM. WILD HORSE CAMPAIGN V. BERNHARDT
    domesticated and semi-feral horses, on the effects of
    castration on other species, and on the natural social behavior
    of wild horses. In that discussion, BLM acknowledged that
    wild horses “are rarely gelded and released back into the
    wild, resulting in few studies that have investigated their
    behavior in free-roaming populations.” Thus, BLM used the
    existing research to predict that those effects likely would be
    insignificant.
    Some “quotient of uncertainty . . . is always present when
    making predictions about the natural world.”
    Id. And we
    have upheld agency predictions despite some uncertainty.
    Id. In Center
    for Biological Diversity, for example, we held that
    the Fish and Wildlife Service made reasonable predictions,
    based on prior data, about the effects of their regulation on
    polar bears even though “the specter of climate change made
    the Service’s prediction less certain than it would be
    otherwise.”
    Id. That the
    agency did not have perfect
    information and had to extrapolate did not make the possible
    effects “highly uncertain” and did not require the preparation
    of an EIS.
    Id. Similarly, in
    EPIC, 
    451 F.3d 1005
    , and Native
    Ecosystems Council, 
    428 F.3d 1233
    , we upheld the
    reasonableness of agency predictions in the face of some
    uncertainty. In EPIC, the precise effects on spotted owls
    could not be “accurately described without additional
    information,” but we held that the agency permissibly
    declined to prepare an EIS because the agency provided
    reasons, based on the available research, for the assumptions
    that it made and for the conclusion that it drew: the effects
    likely would be 
    minor. 451 F.3d at 1011
    (internal quotation
    marks omitted). We also did not fault the agency for not
    preparing an EIS in Native Ecosystems despite imperfect
    AM. WILD HORSE CAMPAIGN V. BERNHARDT                 15
    information and some evidence that the project would have
    negative effects on wildlife. We explained that “the presence
    of some negative effects [does not] necessarily rise[] to the
    level of demonstrating a significant effect on the
    
    environment.” 428 F.3d at 1240
    .
    The same general analysis applies here.            While
    acknowledging that available research was not perfectly
    analogous, BLM used the existing evidence to assess the level
    of uncertainty and made “reasonable predictions on the basis
    of prior data” to conclude that there would be no significant
    environmental impact. Ctr. for Biological 
    Diversity, 588 F.3d at 712
    . BLM did not have to conclude that its project would
    have no effect, but only that there were not substantial
    questions as to whether gelding and release would have a
    significant effect on the environment. Although the
    environmental assessment did not always make BLM’s
    reasoning explicit, we will “uphold a decision of less than
    ideal clarity if the agency’s path may reasonably be
    discerned.” Nat’l Ass’n of Home Builders v. Defs. of
    Wildlife, 
    551 U.S. 644
    , 658 (2007) (internal quotation marks
    omitted).
    Exactly what role geldings will play within the wild-horse
    population when they return to the range is unknown, but
    BLM reasonably concluded that there was no reason to
    expect any behavioral change in individual geldings to be
    significant. BLM explained that, although geldings might
    exhibit some behavioral differences, they will still be free to
    roam unhindered and will have “a number of biological
    impulses” compelling them to do so. Male horses take on a
    number of different roles during their lives, so a change in a
    gelding’s behavior post-castration would not necessarily have
    a significant or adverse effect because the gelding could fit a
    16      AM. WILD HORSE CAMPAIGN V. BERNHARDT
    natural role other than reproducing. BLM further concluded
    that the effects of gelding on individual horses would not be
    more significant than the effects of the alternative—
    permanently removing those horses from public lands.
    BLM likewise considered the effects on family structures
    among wild horses and reasonably concluded that there
    would be no significant effects. BLM cited a study finding
    that the presence of geldings did not disrupt relationships
    between mares and foals. BLM further noted that the plan
    will not geld a large enough number of males to substantially
    reduce population growth rates. Because the number of
    geldings will not be sufficient to affect reproductive patterns,
    it is less likely that geldings would significantly affect other
    family dynamics.
    BLM provided a scientific foundation for its assumptions
    and predictions. We defer to an agency’s “scientific
    prediction[s] within the scope of its technical expertise.” Ctr.
    for Biological 
    Diversity, 588 F.3d at 712
    . Nothing in the
    record, and none of Plaintiffs’ objections, undermines the
    reasonableness of BLM’s conclusion.
    Nor do our prior cases require a different result. In Bark
    v. United States Forest Service, 
    958 F.3d 865
    , 869–71 (9th
    Cir. 2020), we held that the Forest Service’s finding of no
    significant effects was arbitrary and capricious because the
    plaintiffs “pointed to numerous expert sources,” including
    expert studies and research directly contrary to the agency’s
    conclusion, and the agency failed to engage with that body of
    research. By contrast, Plaintiffs have not identified any
    evidence affirmatively showing that returning geldings to the
    range would affect herd behavior. And BLM engaged with
    the currently available scientific evidence either by discussing
    AM. WILD HORSE CAMPAIGN V. BERNHARDT                 17
    the studies expressly or by addressing the concerns that the
    research raised. See In Def. of 
    Animals, 751 F.3d at 1072
    (explaining that an agency must address crucial factors, but
    not necessarily specific evidence regarding that factor).
    Plaintiffs point to the NAS Report as evidence of
    potentially significant effects. But that report acknowledged
    the dearth of applicable scientific evidence and was
    ultimately inconclusive. The report explained that “male-
    type aggressive and sexual behaviors are usually reduced” in
    geldings but that the response varies by individual horse. It
    concluded that whether gelding and release would “increase
    aggression and competition in herds or decrease it” was
    uncertain.
    Only one study of domestic horses found increased
    aggression in geldings. But, as BLM noted, wild male horses
    naturally have varying levels of testosterone and behavior
    depending on a variety of factors. Some change in behavior
    among released geldings, then, would not necessarily be
    disruptive. And a single study does not per se suffice to
    demonstrate highly uncertain effects. See In Def. of 
    Animals, 751 F.3d at 1071
    (finding that the effects of administering
    PZP to horses were not “highly uncertain” despite two studies
    discussing the possible negative effects of PZP on herd
    behavior); Native 
    Ecosystems, 428 F.3d at 1240
    (“[T]he
    presence of some negative effects [does not] necessarily rise[]
    to the level of demonstrating a significant effect on the
    environment.”).
    Finally, there was no other available information that
    BLM should, or could, have used to reduce the uncertainty
    about the effects of gelding and release. Data from BLM’s
    Gelding Study will not be analyzed until later this year. And
    18     AM. WILD HORSE CAMPAIGN V. BERNHARDT
    the mere fact that BLM chose to study the effects of gelding
    and release is not evidence that the effects on herd behavior
    are highly uncertain or might be significant. The study will
    provide information not only about the effects on herd
    behavior, but also about the effectiveness of gelding as a
    population control method. Because the Gather Plan’s use of
    gelding was not primarily intended as a population control
    tool, any uncertainty regarding gelding’s effect on population
    growth is not significant. The Gelding Study reveals BLM’s
    opinion that the effects on herd behavior are not fully
    understood but does not suggest that BLM expects the effects
    to be significant—or even that there will be an effect at all.
    For that reason, our decision in National Parks &
    Conservation Ass’n v. Babbitt, 
    241 F.3d 722
    (9th Cir. 2001),
    abrogated on other grounds as recognized by Monsanto Co.
    v. Geertson Seed Farms, 
    561 U.S. 139
    , 157 (2010), is
    inapposite. In that case, although the effects of the proposed
    action were uncertain to some extent, the scientific evidence
    revealed definite adverse effects.
    Id. at 732.
    The uncertainty
    was over the intensity of the effects,
    id., and “[n]o
    new
    scientific developments [were] required in order to obtain the
    requisite information,”
    id. at 735.
    Under those circumstances,
    the preparation of an EIS could help decision-makers better
    understand the effects of the project.
    Similarly, in Ocean Advocates v. United States Army
    Corps of Engineers, 
    402 F.3d 846
    , 867 (9th Cir. 2005), we
    identified evidence in the record that the agency’s action
    would have an “unquestionably severe” effect on the
    environment. We noted that the agency failed to collect
    available data, conduct projection analyses, or provide a
    “justification regarding why more definitive information
    could not be provided.”
    Id. at 870–71
    (internal quotation
    AM. WILD HORSE CAMPAIGN V. BERNHARDT                 19
    marks omitted). Here, by contrast, the uncertainty is whether
    gelding and release will have any effect at all on the behavior
    of wild horses. BLM is not required to wait years before
    taking action simply because an ongoing study might shine
    light on an uncertainty that BLM reasonably predicts will be
    minor or nonexistent.
    After a thorough review of the evidence that was
    available, BLM made “reasonable predictions” about the
    relevant area of uncertainty. Ctr. for Biological 
    Diversity, 588 F.3d at 712
    . Where there was no evidence that there
    would be an effect, BLM was not required to conduct
    additional research or wait for the results of the Gelding
    Study before moving forward with its proposed action. The
    NAS Report’s inconclusive statements and a single study
    about domestic geldings does not undermine BLM’s
    reasonable prediction that gelding and release will have
    insignificant effects on herd behavior. BLM’s conclusion,
    then, that the likelihood of significant effects of gelding was
    not so uncertain as to require an EIS was not arbitrary or
    capricious. 
    EPIC, 451 F.3d at 1009
    .
    2. Highly Controversial
    The effects of the Gather Plan are not “highly
    controversial.” 40 C.F.R. § 1508.27(b)(4). The evidence that
    Plaintiffs identify does not “cast[] serious doubt upon the
    reasonableness of [the] agency’s conclusions.” Humane
    Soc’y of U.S. v. Locke, 
    626 F.3d 1040
    , 1057 (9th Cir. 2010)
    (internal quotation marks omitted). Plaintiffs have not
    identified any evidence that contradicts BLM’s findings. The
    NAS Report was inconclusive and reported no findings that
    conflict directly with those in the environmental assessment.
    The expert opinions that Plaintiffs cite were not based on
    20     AM. WILD HORSE CAMPAIGN V. BERNHARDT
    studies that those experts had conducted, and no existing
    research supported their speculation. Mere opposition to an
    action does not, by itself, create a controversy within the
    meaning of NEPA regulations.
    Id. BLM considered
    and
    addressed the existing literature in its environmental
    assessment and provided reasoning for its conclusions. That
    satisfies NEPA. See Native 
    Ecosystems, 428 F.3d at 1240
    (“Simply because a challenger can cherry pick information
    and data out of the administrative record to support its
    position does not mean that a project is highly controversial
    . . . .”).
    3. Unique Characteristics
    BLM’s determination that the gather area is not in close
    “proximity to historic or cultural resources” was not arbitrary
    or capricious. 40 C.F.R. § 1508.27(b)(3). Wild horses are
    not a cultural resource for purposes of NEPA. Congress,
    through the Wild Free-Roaming Horses and Burros Act,
    decided how wild horses should be managed and how the
    effects of agency actions on those horses should be evaluated.
    The Act states that wild horses will be considered “an integral
    part of the natural system of the public lands,” 16 U.S.C.
    § 1331, and specifically instructs that they should be managed
    “as components of the public lands” and as a part of a
    “natural ecological balance.”
    Id. § 1333(a).
    A specific
    statute, such as the Act’s directive as to how to manage wild
    horses, governs over a general provision, such as NEPA.
    Perez-Martin v. Ashcroft, 
    394 F.3d 752
    , 758 (9th Cir. 2005);
    see City & Cty. of San Francisco v. U.S. Citizenship &
    Immigration Servs., 
    944 F.3d 773
    , 800 (9th Cir. 2019) (“We
    cannot see how a general provision in one statute constrains
    an agency given a specific charge in a subsequent law.”).
    AM. WILD HORSE CAMPAIGN V. BERNHARDT                21
    4. Precedent
    The Gather Plan does not establish “a precedent for future
    actions with significant effects,” nor does it represent “a
    decision in principle about a future consideration.” 40 C.F.R.
    § 1508.27(b)(6). The Gather Plan does not establish gelding
    as an accepted population-management tool, nor is it the first
    instance of BLM’s releasing geldings to the range. The
    conclusions in the environmental assessment for the Gather
    Plan are specific to the scientific evidence that is currently
    available. Like most environmental assessments, the Gather
    Plan’s environmental assessment is “highly specific to the
    project and the locale.” In Def. of 
    Animals, 751 F.3d at 1071
    .
    5. Threatens a Violation of Law
    Finally, because BLM has followed the mandates of the
    Wild Free-Roaming Horses and Burros Act, its decision to
    geld and release does not threaten a violation of federal law.
    40 C.F.R. § 1508.27(b)(10). BLM adequately addressed the
    relevant factors raised by the NAS Report and the expert
    opinions submitted during the public comment period to
    satisfy the requirements of the Act, as discussed in Parts B.2
    and B.3, below.
    We conclude that BLM permissibly determined that the
    intensity factors, whether considered individually or
    collectively, did not show that the Gather Plan would have a
    significant effect on the environment. Accordingly, BLM
    permissibly concluded that preparation of an EIS was not
    required.
    22      AM. WILD HORSE CAMPAIGN V. BERNHARDT
    B. Authorization of Gelding and Release
    Plaintiffs also argue that BLM acted arbitrarily and
    capriciously because it did not address the Gelding Study, did
    not consider the expert opinions that Plaintiffs highlighted in
    their public comments, and did not consider adequately the
    NAS Report.
    1. Gelding Study
    BLM did not discuss at length its Gelding Study in its
    environmental assessment for the Gather Plan; nor did it wait
    to authorize gelding and release until it obtained data from
    the Study. But BLM considered and addressed the relevant
    factor that the Gelding Study raised and explained why
    additional information was not available, which meets
    NEPA’s “hard look” standard. In Def. of 
    Animals, 751 F.3d at 1072
    –73.
    BLM adequately considered the effect of releasing
    geldings back to the range both on the geldings themselves
    and on the rest of the wild-horse population. Because the
    Gelding Study has not yet provided any new information on
    the factor, it was reasonable for BLM not to mention that
    study in the preliminary environmental assessment.
    Nevertheless, after BLM received comments that more
    research was needed on the effects of gelding, it included a
    brief discussion of the Gelding Study in its final
    environmental assessment, explaining that results would not
    be available for several years. BLM thus adequately
    explained why additional data was unavailable. Cf. Ocean
    
    Advocates, 402 F.3d at 870
    –71 (finding an agency’s failure to
    collect available data or provide a “justification regarding
    AM. WILD HORSE CAMPAIGN V. BERNHARDT                 23
    why more definitive information could not be provided” was
    arbitrary and capricious).
    The Gather Plan’s use of gelding also does not reflect an
    unexplained inconsistency that would violate the
    Administrative Procedure Act. See Humane 
    Soc’y, 626 F.3d at 1051
    (concluding that an agency’s action was arbitrary and
    capricious because the agency failed to explain inconsistent
    factual findings). Plaintiffs argue that, in the environmental
    assessment for the Gelding Study, BLM found that it needed
    the results of that study before it could make informed
    decisions about gelding wild horses. In Plaintiffs’ view,
    because the Gather Plan included gelding and release without
    explaining why BLM no longer deemed the Study’s results
    necessary for informed decision-making, BLM acted
    arbitrarily and capriciously.
    BLM made no such finding in its environmental
    assessment for the Gelding Study. That document merely
    acknowledged that some uncertainty remained regarding the
    effects of gelding on wild horses and that additional
    information could improve its decision-making. The
    intention of the Gelding Study is to augment BLM’s
    understanding of gelding, not to dictate its future conduct and
    decisions. The Gather Plan similarly includes measures to
    help improve BLM’s understanding of gelding and release:
    BLM will monitor and observe the behavior of released
    geldings to determine whether they are freely moving, how
    they intermix with the breeding population, and if replacing
    breeding mares with geldings can be an effective approach to
    slowing the rate of population growth. Those plans are
    consistent with BLM’s ongoing efforts to better understand
    the effects of gelding, as described in the Gelding Study’s
    environmental assessment. There was neither a change in
    24     AM. WILD HORSE CAMPAIGN V. BERNHARDT
    practice nor an inconsistency with previous findings that
    BLM was required to explain.
    2. Expert Opinions
    The Wild Free-Roaming Horses and Burros Act does not
    require BLM to discuss explicitly all expert opinions
    submitted during the public-comment period. See 16 U.S.C.
    § 1333(b)(1) (requiring that the agency consult individuals
    recommended by the National Academy of Sciences, but
    leaving it to the Secretary’s discretion whether to consult
    “other individuals” with “scientific expertise and special
    knowledge”). In its response to the public comments, BLM
    provided reasons for not relying on those experts’ opinions
    and referred to portions of the environmental assessment that
    addressed those experts’ substantive concerns. That is a
    sufficient explanation for us to conclude that BLM’s choice
    was not arbitrary or capricious. See In Def. of 
    Animals, 751 F.3d at 1073
    (noting that we do not require an agency to
    “recite its reasons for relying on the studies cited in [an
    environmental assessment] as opposed to the studies cited by
    [a] comment” to show that the agency “performed the ‘hard
    look’ required by NEPA”).
    3. National Academy of Sciences Report
    By addressing the concerns and factors that the NAS
    Report raised, BLM complied with the Wild Free-Roaming
    Horses and Burros Act’s requirement that BLM “consult” the
    National Academy of Sciences to make determinations about
    how appropriate management levels should be achieved.
    16 U.S.C. § 1333(b)(1). The report concluded that “[t]he
    effect that gelding a portion of the males in a herd would have
    on reproduction and behavior could not be predicted at the
    AM. WILD HORSE CAMPAIGN V. BERNHARDT                 25
    time this report was prepared.” BLM acknowledged that
    uncertainty in the environmental assessment and discussed
    the evidence of potentially adverse effects of gelding.
    The only concern that BLM did not address expressly was
    the NAS Report’s discussion of vasectomy as an alternative
    to gelding.      Public comments on the preliminary
    environmental assessment brought this alternative to BLM’s
    attention, but BLM did not address it in the final
    environmental assessment, either. The NAS Report, though,
    was ambivalent in its support of vasectomy, noting that
    surgical vasectomy creates some risks to herds. And BLM’s
    guidebook, which was included in the record, states that
    vasectomies are not widely performed on stallions and that
    additional research is needed to “perfect a safe technique”
    and “demonstrate whether this approach will reduce
    population growth rates”—reflecting a similar level of
    uncertainty as with gelding.
    Because evidence in the record supports BLM’s choice of
    gelding, and because we can discern the reasons for BLM’s
    rejection of the alternative of surgical vasectomy, Nat’l Ass’n
    of Home 
    Builders, 551 U.S. at 658
    , BLM’s failure to respond
    explicitly to the comments about vasectomies was not
    arbitrary or capricious. See In Def. of 
    Animals, 751 F.3d at 1072
    (noting that NEPA does not require an agency “to
    address in detail the substance conveyed in every single
    comment made on an [environmental assessment] to prove
    that the agency ‘considered’ the relevant factors”).
    AFFIRMED.