Endangered and Threatened Wildlife and Plants; Threatened Species Status With Section 4(d) Rule for the Silverspot Butterfly, 11750-11772 [2024-03042]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 89, Number 32 (Thursday, February 15, 2024)]
[Rules and Regulations]
[Pages 11750-11772]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-03042]



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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R6-ES-2021-0134; FF09E21000 FXES1111090FEDR 245]
RIN 1018-BE98


Endangered and Threatened Wildlife and Plants; Threatened Species 
Status With Section 4(d) Rule for the Silverspot Butterfly

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine 
threatened species status under the Endangered Species Act of 1973 
(Act), as amended, for a subspecies of butterfly (Speyeria nokomis 
nokomis), a silverspot butterfly from Colorado, New Mexico, and Utah. 
We also finalize a rule issued under the authority of section 4(d) of 
the Act that provides measures that are necessary and advisable to 
provide for the conservation of this subspecies. We have determined 
that the designation of critical habitat is not prudent.

DATES: This rule is effective March 18, 2024.

ADDRESSES: This final rule is available on the internet at https://www.regulations.gov at Docket No. FWS-R6-ES-2021-0134. Comments and 
materials we received, as well as supporting documentation we used in 
preparing this rule, are available for public inspection at https://www.regulations.gov at Docket No. FWS-R6-ES-2021-0134.

FOR FURTHER INFORMATION CONTACT: Nathan Darnall, Western Colorado 
Supervisor, U.S. Fish and Wildlife Service, Colorado Ecological 
Services Field Office, 445 West Gunnison Avenue, Grand Junction, CO 
81501; telephone 970-628-7181. Individuals in the United States who are 
deaf, deafblind, hard of hearing, or have a speech disability may dial 
711 (TTY, TDD, or TeleBraille) to access telecommunications relay 
services. Individuals outside the United States should use the relay 
services offered within their country to make international calls to 
the point-of-contact in the United States.

SUPPLEMENTARY INFORMATION:

Executive Summary

    Why we need to publish a rule. Under the Act, a species warrants 
listing if it meets the definition of an endangered species (in danger 
of extinction throughout all or a significant portion of its range) or 
a threatened species (likely to become endangered within the 
foreseeable future throughout all or a significant portion of its 
range). If we determine that a species warrants listing, we must list 
the species promptly and designate the species' critical habitat to the 
maximum extent prudent and determinable. We have determined that the 
silverspot butterfly meets the Act's definition of a threatened 
species; therefore, we are listing it as such. Listing a species as an 
endangered or threatened species can be completed only by issuing a 
rule through the Administrative Procedure Act rulemaking process (5 
U.S.C. 551 et seq.). We have determined that the designation of 
critical habitat is not prudent due to the threat of collection.
    What this document does. This rule finalizes the listing of the 
silverspot butterfly as a threatened species with a rule issued under 
the authority of section 4(d) of the Act (a ``4(d) rule'').
    The basis for our action. Under the Act, we may determine that a 
species is an endangered or threatened species because of any of five 
factors: (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range; (B) overutilization for 
commercial, recreational, scientific, or educational purposes; (C) 
disease or predation; (D) the inadequacy of existing regulatory 
mechanisms; or (E) other natural or manmade factors affecting its 
continued existence. We have determined that the silverspot butterfly 
is threatened due to the individual and cumulative effects of habitat 
loss and fragmentation (Factor A), incompatible livestock grazing 
(Factor A), human-caused hydrologic alteration (Factor A), genetic 
isolation (Factor E), and climate change (Factor E).
    Section 4(a)(3) of the Act requires the Secretary of the Interior 
(Secretary), to the maximum extent prudent and determinable, to 
designate critical habitat concurrent with listing. We have determined 
that designating critical habitat is not prudent for the silverspot 
butterfly at this time, for the reasons discussed below in section III. 
Critical Habitat.

Previous Federal Actions

    Please refer to the May 4, 2022, proposed rule (87 FR 26319) to 
list the silverspot butterfly for a detailed description of previous 
Federal actions concerning this subspecies.

Peer Review

    A species status assessment (SSA) team prepared an SSA report for 
the silverspot butterfly (hereafter, silverspot). The SSA team was 
composed of Service biologists, in consultation with other species 
experts. The SSA report represents a compilation of the best scientific 
and commercial data available concerning the status of the subspecies, 
including the impacts of past, present, and future factors (both 
negative and beneficial) affecting the subspecies.
    In accordance with our joint policy on peer review published in the 
Federal Register on July 1, 1994 (59 FR 34270), and our August 22, 
2016, memorandum updating and clarifying the role of peer review of 
listing actions under the Act, we solicited independent scientific 
review of the information contained in the silverspot SSA report. We 
sent the SSA report to four appropriate and independent peer reviewers 
and received four responses. Results of this structured peer review 
process can be found at https://www.regulations.gov at Docket No. FWS-
R6-ES-2021-0134. We incorporated the results of these reviews, as 
appropriate, into the SSA report, which is the foundation for the May 
4, 2022, proposed rule and this final rule. A summary of the peer 
review comments and our responses can be found in the ``Summary of 
Public Comments and Recommendations'' below.

Summary of Changes From the Proposed Rule

    After consideration of the comments we received during the public 
comment period on the May 4, 2022, proposed rule (87 FR 26319), we made 
changes to this final rule. In addition to minor editorial changes, we 
updated information in this final rule and the SSA report (Service 
2023, entire) based on comments and additional information provided, as 
follows:
    First, we incorporated new survey information from 2021 and 2022 
for six populations (Garfield, Mesa/Grand, Montrose/San Juan, Ouray, 
San Miguel/Mora, and Taos) into the SSA report and our evaluation of 
current and future condition in this final rule. Recent surveys for 
these populations provided updated information on the number of 
colonies and habitat acreage. There are now 21 known silverspot 
colonies grouped into 10 populations, an increase from the 19 colonies 
reported in the May 4, 2022, proposed rule (the number of silverspot 
populations has not changed). There are now known to be approximately 
714 habitat acres (289

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hectares (ha)) within the 10 populations, a slight increase from the 
710.5 acres (287.5 ha) reported in the May 4, 2022, proposed rule. This 
information resulted in changes to resiliency scores identified in 
tables 1 and 2 of the May 4, 2022, proposed rule, and the current and 
future resiliency condition categories for three (Garfield, Mesa/Grand, 
and San Miguel/Mora) of the six populations with new survey information 
(see Service 2023, pp. 8, 39-48). These changes include both increases 
and decreases in current and future resiliency scores, depending on the 
population (see tables 1 and 2, below). This information improves our 
understanding of the silverspot's status.
    Second, we incorporated into the SSA report a change to the 
categories that we used to evaluate the current status of silverspot 
populations (extant, likely extant, intermittent, unknown, likely 
extirpated, extirpated) as shown in the resiliency tables (see Service 
2023, pp. 8, 40-47). We no longer consider there to be a relevant 
distinction between the ``intermittent'' and ``unknown'' status 
categories given the similar levels of uncertainty ascribed to their 
status. Therefore, we merged the two categories into the ``unknown'' 
category, and, as a result, we changed the status of the Garfield and 
LaPlata populations from intermittent to unknown. This change 
simplifies and better delineates the status categories for the 
subspecies and does not affect the scoring of current and future 
condition.
    Third, we updated the range map in the SSA report and removed 
higher elevation areas. Now, the range map only identifies areas within 
the elevation range of the silverspot (Service 2023, pp. 16, 18).
    Finally, we made the following changes to the preamble discussion 
and/or regulatory text of the 4(d) rule:
    (1) We added an exception for maintenance and operation of existing 
utility infrastructure within existing rights-of-way (for more 
information, see ``Provisions of the 4(d) Rule'' below); and
    (2) We made editorial corrections to the wording of certain 
exceptions in the regulatory text of the 4(d) rule to increase clarity 
and to better align the language with existing regulations and law. 
These corrections include revisions such as specifying that a machine 
blade's height be measured from ``above the ground'' and that certain 
excepted activities can occur ``year-round.'' These editorial 
corrections do not alter the original meaning of these exceptions.

Summary of Public Comments and Recommendations

    In the proposed rule published on May 4, 2022 (87 FR 26319), we 
requested that all interested parties submit written comments on the 
proposal by July 5, 2022. We also contacted appropriate Federal and 
State agencies, Tribes, scientific experts and organizations, and other 
interested parties and invited them to comment on the proposal. On May 
3, 2022, we published a press release on our website inviting the 
public to comment. On May 4, 2022, a newspaper notice inviting general 
public comment was also published in the Grand Junction Daily Sentinel. 
We did not receive any requests for a public hearing. All substantive 
information we received during the comment period has either been 
incorporated directly into this final determination, has been used to 
clarify the information in the SSA report, or is addressed below.

Peer Reviewer Comments

    As discussed in ``Peer Review'' above, we received comments from 
four peer reviewers on the draft SSA report. We reviewed all comments 
we received from the peer reviewers for substantive issues and new 
information regarding the contents of the SSA report. Peer reviewer 
comments are addressed in the following summary. As discussed above, 
because we conducted this peer review prior to the publication of our 
proposed rule, we had already incorporated all applicable peer review 
comments into version 1.0 of the SSA report, which was the foundation 
for the proposed rule and this final rule. The four peer reviewers 
provided additional information, clarifications, and recommendations 
that we have either incorporated into the SSA report or address below. 
We received a few comments on recovery efforts for the silverspot. We 
note these for future reference in recovery planning but do not respond 
here because they are outside the scope of this rulemaking.
    (1) Comment: One reviewer recommended including more discussion in 
the SSA report about the results of a recent genetic study (Cong et al. 
2019, entire) regarding the timing of introgression (also known as 
introgressive hybridization, the transfer of genetic material between 
species following hybridization by repeated backcrossing of an 
interspecific hybrid with one of its parent species) between the 
silverspot and other species or subspecies, and how populations became 
introgressed. The reviewer also recommended that we evaluate 
introgression as a future threat to the silverspot if this would result 
in the loss of the subspecies' conservation value.
    Our response: We did not add more discussion on this topic to the 
SSA report because the document already has a summary of the genetic 
variation and introgression results from the recent genetic study 
referenced by the reviewer (Cong et al. 2019, entire). In the SSA 
report, we refer to introgression as hybridization that resulted in 
hybrid segregates or intermediate hybrids with various levels of 
genetic mixing between Speyeria nokomis nokomis, S. n. apacheana, and 
S. n. nitocris (Service 2023, pp. 13-14). We also stated that various 
levels of hybridization occurred historically between the silverspot 
and other subspecies, but that hybridization declined under warmer, 
drier climate conditions since the last ice age as the subspecies 
became isolated from each other. There is evidence of isolation between 
the silverspot and the other subspecies or hybrids that has persisted 
for centuries (over the last few hundred years or longer). We also 
identify genetic isolation as a threat to the silverspot based on the 
distances between known populations (see Factors Influencing Subspecies 
Viability, below). Given the low likelihood of current or future 
hybridization, we do not consider hybridization to be a threat to the 
silverspot.
    (2) Comment: One reviewer stated their concern with the current 
distribution description in the SSA report and the treatment of known 
sites as somewhat fixed in both space and time. The reviewer felt that 
the presence of undiscovered colonies within each population could have 
important consequences for colony persistence by augmenting known 
populations both demographically and genetically, thereby increasing 
resilience. The reviewer noted there is documentation of this in one 
Great Basin Speyeria n. apacheana colony (Britten et al. 2003, entire). 
The reviewer suggested that some discussion of this possibility and a 
description of systematic efforts that have been made to find 
additional colonies within the subspecies' range (as shown on the SSA 
report's range map) should be included.
    Our response: We acknowledge that species can shift their ranges 
over space and time. The range map in the SSA report (Service 2023, p. 
18) is based on the best available information at the time it was 
created, and we will update the SSA report and range map as new 
information becomes available for the subspecies. We also characterize 
the importance of colonies for population

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persistence, demographics, and genetics in the SSA report (Service 
2023, pp. 17, 23-26, 35-36). The demographic and genetic benefits of 
connectivity between known colonies would apply to undiscovered 
colonies, and we added this statement to the SSA report (Service 2023, 
p. 35). We are not able to disclose details or results of systematic 
survey efforts and colony locations due to the threat of collection; 
however, we have surveyed, and will continue to survey, historical 
locations and potential habitat to determine the presence or absence of 
the silverspot.
    (3) Comment: One reviewer agreed with the definition of the 
silverspot's occupied habitat, the individual site descriptions 
presented in the SSA report, and how current and past habitat patches 
have changed through time. However, the reviewer noted that the SSA 
report does not include implications of the long-term dynamics of 
habitat quality and dispersion. The reviewer thought a more in-depth 
analysis of the dynamic nature of the butterfly's habitat and 
population fluctuations would be helpful to the long-term persistence 
of the subspecies even if it is based on educated opinion. The reviewer 
stated that there is enough information to at least speculate on the 
potential for the silverspot to follow its habitat, or find newly 
formed habitat, as climate change and other perturbations alter the 
current distribution of its habitat. The reviewer wondered if there are 
places within the current distribution where butterfly colonies could 
move upslope as the current habitat becomes unsuitable due to warming. 
A second reviewer stated that climate change could cause small 
elevation shifts in silverspot colonies.
    Our response: Currently, we do not have sufficient information to 
make a reliable or well-informed projection of the silverspot's ability 
to find newly formed habitat or occupy higher elevation habitat if 
climate change or habitat loss and fragmentation alter its current 
distribution. We lack detailed information on the locations of bog 
violet populations across the range and in higher elevations. One 
species expert stated that the silverspot was not likely to move 
upslope in a warmer/drier climate unless habitat is continuous and the 
bog violet already occurs there (Ellis 2020b, pers. comm.; Service 
2023, p. 50). We will develop a recovery plan and recovery actions for 
the silverspot to improve our understanding of the silverspot and 
perhaps its ability to occupy higher elevation habitats.
    (4) Comment: One reviewer recommended referring to a silverspot 
population as a metapopulation because colonies connected by 
demographic and genetic exchange are better described as 
metapopulations.
    Our response: We use the term metapopulation when discussing 
silverspot populations with more than one colony. However, in the SSA 
report, we continue to use the term population in general, because 
there are also many single colony silverspot populations, and it is a 
standard term we use to describe the groupings of silverspots we used 
in our analysis of resiliency and viability.
    (5) Comment: One reviewer supported the subspecies delineation 
presented in the recent genetic study (Cong et al. 2019, entire) and 
the SSA report. However, the reviewer noted that while the genetic 
study uses strong methods, it has not been peer-reviewed and lacks some 
details about methods and analyses. The reviewer recommended a 
discussion in the SSA report about the level of confidence in the 
results and why we identify 10 major populations for the genus, 
Speyeria. Their interpretation of the results was that a delineation of 
13 populations was better supported than the 10 populations we state in 
the SSA report.
    Our response: We report the results and conclusions of the draft 
genetic study (Cong et al. 2019, entire) in the SSA report because the 
draft genetic study provides the best available information on the 
genetics of the silverspot and the other Speyeria nokomis subspecies. 
We are confident in the results of the draft study because of the 
researchers' genetic expertise despite the fact that the study has not 
been peer-reviewed. We will update the SSA report as needed to reflect 
major changes, if any, once the genetic study is published.
    (6) Comment: One reviewer stated that the SSA report does not 
include published reports of Speyeria nokomis apacheana to their full 
potential. The reviewer noted that the ecology and life history of S. 
n. nokomis and S. n. apacheana are similar and suggested that S. n. 
apacheana should serve as a good surrogate for S. n. nokomis where data 
are lacking. The reviewer noted that two reports document gene flow 
among S. n. apacheana colonies that may mitigate the effects of genetic 
drift (the loss of alleles (version of a gene) or change in their 
frequency in a population) on colony genetic diversity (Britten et al. 
1994, entire; Britten 2003, entire). The reviewer noted that S. n. 
apacheana also experiences high levels of colony turnover and routinely 
disperses about 4 kilometers (about 2.5 miles) from natal (birth) sites 
based on years of mark/recapture studies at several locations in Nevada 
(Fleishman et al. 2002, entire). The reviewer noted that the SSA report 
concluded that about 10 miles is a good estimate of S. n. nokomis 
dispersal distance but questioned whether estimates of the silverspot's 
viability would differ if shorter dispersal distances, closer to those 
of S. n. apacheana, were applied in the SSA report.
    Our response: In the SSA report, we evaluate connectivity between 
silverspot populations based on their estimated long-distance dispersal 
ability of 5 to 10 miles (Ellis 2020c, 2020d, 2020e, pers. comm.) and 
the potential for longer term gene flow between colonies within a 20-
mile distance based on the recent genetic study (Cong et al. 2019, 
entire). Taken together, these distances characterize the potential for 
gene flow and population connectivity over short-term and long-term 
timeframes and provide a more appropriate evaluation of gene flow than 
the annual dispersal distances for the silverspot and Speyeria nokomis 
apacheana. Therefore, we did not change the metrics we used to evaluate 
resiliency, although we note that the shorter, annual dispersal 
distances the reviewer mentions would receive the highest score for 
genetic connectivity in our analysis because those distances allow for 
a high level of genetic interchange and maintenance of a metapopulation 
structure.
    (7) Comment: One reviewer stated that collecting has never been 
shown to cause the extirpation of an insect population or species 
because it is a density-independent factor.
    Our response: The reviewer did not provide information to support 
their comment. Many of the silverspot populations are small and 
currently in low resiliency condition, and therefore could be easily 
extirpated if collection pressure increased. The best available 
information indicates that poaching of rare and imperiled taxa for 
profit does occur, even to the point of driving a species to extinction 
to increase the value of individual specimens (Kleiner 1995, entire; 
Hoekwater 1997, entire; Courchamp et al. 2006, entire; O'Neill 2007, 
entire; Stratton 2012, entire).
    (8) Comment: One reviewer stated that changes in water management 
are the most likely immediate threat to silverspot populations based on 
the decline of other S. nokomis subspecies' colonies from the capping 
of springs and water diversions.
    Our response: We consider hydrologic alteration to be a major 
factor affecting the subspecies (see Factors Influencing Subspecies 
Viability, below). We recognize that water management can

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result in the loss or alteration of silverspot habitat, and that 
extensive hydrologic alteration has occurred within the range of the 
silverspot for agricultural, commercial, and municipal purposes. The 
reviewer did not recommend any changes to our analysis, and we 
accounted for water management practices and hydrologic alteration of 
silverspot habitat in the habitat factor score for current and future 
condition (see Summary of Biological Status and Threats, below).
    (9) Comment: One reviewer stated that some colonies may require 
management, such as light grazing or mowing, to maintain habitat 
suitability. For example, the Speyeria nokomis apacheana population in 
Round Valley (Inyo County, California) has persisted at least over the 
past 70 years under a regime of light grazing. Conversely, the reviewer 
noted that heavy park-like mowing of the Mono County Park near Mono 
Lake, California, caused the extirpation of a small colony.
    Our response: We agree that light grazing or mowing in addition to 
other occasional disturbances, such as burning or non-catastrophic 
flooding, are needed to maintain suitable habitat conditions for the 
silverspot. We identify some of these practices as exceptions to the 
take prohibitions under the 4(d) rule (see ``Provisions of the 4(d) 
rule'' below). We intend to work with landowners or managers to provide 
occasional disturbance or even light annual disturbance that is 
compatible with conserving the silverspot and the bog violet.
    (10) Comment: A reviewer stated that the current common name for 
the species is Nokomis Fritillary according to the North American 
Butterfly Association (NABA) Common Names List, which is the recognized 
source for North American butterfly species. However, the reviewer 
noted that there is no recognized source for subspecies' common names.
    Our response: We state that Nokomis Fritillary is the accepted 
common name for the species, Speyeria nokomis, in the SSA report 
(Service 2023, appendix C, p. 80). We refer to the subspecies that is 
the subject of this document, S. n. nokomis, as the silverspot to 
distinguish it from the other Nokomis Fritillary subspecies and to 
minimize public confusion once it is listed under the Act. Prior to the 
recent genetic study (Cong et al. 2019, entire), which clarified the 
range of the subspecies, we referred to the silverspot butterfly as the 
Great Basin silverspot butterfly, a common name that is no longer 
applicable (see 87 FR 26319, May 4, 2022, p. 26322). We will report 
updates to its common name and taxonomy, if needed, in the SSA report 
and future 5-year status reviews to be consistent with the accepted 
taxonomic nomenclature. We note in the SSA report that the silverspot 
and other members of the Nokomis genus may be assigned to a different 
genus (Argynnis) soon (Service 2023, p. 13). This change in genus would 
likely not affect the silverspot's listing status under the Act.

Comments From States

    (11) Comment: The Utah Public Lands Policy Coordination Office 
(PLPCO) of the Utah Governor's Office stated that they advocate for 
silverspot conservation and are available to assist in the development 
of a conservation strategy for the subspecies. They expressed that the 
most effective conservation strategy is to coordinate with State 
agencies, local governments, and landowners because the silverspot is 
mostly on private lands. The PLPCO also supported our determination 
that the designation of critical habitat is not prudent for the 
silverspot.
    Our response: We welcome participation by the PLPCO and any 
stakeholder or landowner to provide conservation for the silverspot 
through the development of a conservation strategy or other means. We 
agree that State and local support will be critical to the recovery and 
successful management of the silverspot.
    (12) Comment: The PLPCO expressed that managed grazing, burning, 
mowing, and non-catastrophic flooding are necessary to remove harmful 
and invasive vegetation to benefit the silverspot and its host plants. 
They suggested that lack of grazing could lead to population extinction 
of the silverspot based on a published study from another endangered 
butterfly, the Quino checkerspot (Preston et al. 2012, entire).
    Our response: The SSA report (Service 2023, entire), proposed rule 
(87 FR 26319; May 4, 2022), and this final rule state that managed 
grazing, burning, mowing, and non-catastrophic flooding can benefit the 
silverspot. Livestock grazing that is done in a manner consistent with 
local ecological conditions, including soil types, precipitation zones, 
vegetation composition, and drought conditions, to provide early seral 
or more open conditions for the bog violet can be compatible with the 
needs and conservation of the silverspot. For more information, see the 
discussions under ``Summary of Biological Status and Threats'' and 
``Beneficial Factors'' below. We also recognize that maintenance of 
sustainable grazing practices on private lands can aid in recovery of 
the silverspot by discouraging further conversion of the species' 
habitat into habitat unsuitable to the species (i.e., due to 
development).
    We reviewed the Preston et al. 2012 paper, and it does not state 
that lack of grazing resulted in the extinction or extirpation of the 
Quino checkerspot (Euphydryas editha quino), which is currently listed 
as endangered under the Act. However, the paper did reference another 
article (Weiss 1999, entire) related to beneficial grazing practices to 
suppress nonnative plants in butterfly populations. We have 
incorporated this article into the SSA report (Service 2023, p. 38).
    (13) Comment: The New Mexico Department of Agriculture (NMDA) and 
others expressed concern that the range map of the silverspot in the 
SSA report (Service 2021, p. 12) is overly broad relative to the small 
amount of known, occupied habitat, and includes elevations much higher 
than the upper elevation for the butterfly. The NMDA recommended the 
use of range delineation methods from a published article (Burgman and 
Fox 2003, entire) to refine the subspecies' range. Another commenter 
suggested the range map in the 2021 SSA report is an example of a 
flawed habitat model that could be corrected with a more detailed 
discussion of why the area is thought to be suitable, and the commenter 
provided a definition of wildlife habitat to improve how we define 
habitat in the proposed rule. Both commenters expressed the need for 
comprehensive surveys and improvements to the habitat model to better 
define suitable, occupied habitat, and the silverspot's range, to 
reduce unnecessary regulatory burden.
    Our response: We have updated the range map in the SSA report and 
removed higher elevation areas to address the comment. Now, the range 
map in the SSA report identifies only areas within the known elevation 
range of the silverspot (Service 2023, p. 18). The range map provides 
an intentionally broad delineation of the current extent of the 
silverspot's range to protect the exact locations of colonies and 
should not be used or considered as a habitat model for the subspecies. 
We acknowledge that most of the lands identified in the range map are 
not suitable habitat for the silverspot; the subspecies is a habitat 
specialist with very specific habitat needs.
    We do not have a habitat model for the silverspot; however, when 
this rule is effective (see DATES, above), we intend to develop one 
using the best available habitat information and

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methods used by the Service, which are consistent with those 
recommended in the published paper recommended by the commenter 
(Burgman and Fox 2003, entire) (see Service 2019, entire). Once 
developed, the suitable habitat model will inform the need for surveys, 
and additional surveys would better delineate occupied habitat, 
suitable habitat, and the current range of the subspecies.
    (14) Comment: The NMDA and others requested time to implement 
proactive conservation and education in cooperation with private 
landowners, Federal land managers, and lessees prior to a final listing 
determination for the silverspot. They state that there are beneficial 
management practices for the silverspot that have yet to be 
implemented.
    Our response: The commenters are correct that beneficial management 
practices have not been implemented for the silverspot, and we welcome 
participation by States, counties, landowners, or other stakeholders to 
implement conservation and recovery efforts for the subspecies. Under 
the Act, we must list a species or subspecies if it meets the 
definition of an endangered species or a threatened species. Moreover, 
our policy for the evaluation of conservation efforts when making 
listing decisions (PECE policy; 68 FR 15100, March 28, 2003) identifies 
criteria we use in determining whether formalized conservation efforts 
that have yet to be implemented or to show effectiveness contribute to 
making listing a species as endangered or threatened unnecessary. The 
PECE policy applies to conservation efforts identified in conservation 
agreements, conservation plans, management plans, or similar documents 
developed by Federal agencies, State and local governments, Tribal 
governments, businesses, organizations, and individuals. For the 
silverspot, there were no formalized conservation efforts that had yet 
to be implemented prior to this final rule for us to consider under the 
PECE policy.
    (15) Comment: The NMDA expressed that the 4(d) rule should ensure 
that private landowners and public land managers will not be exposed to 
risk of take of the silverspot for their normal agricultural activities 
in wet meadows that do not contain the silverspot within its range. 
They recommend the 4(d) rule clarify that take of the silverspot from 
habitat modification only applies to areas where the silverspot is 
found (known colonies) and requested that we modify the specific take 
prohibition in the 4(d) rule to reflect that.
    Our response: Under 50 CFR 17.31(c), for a species listed as a 
threatened species, the species-specific 4(d) rule will contain all the 
applicable prohibitions and exceptions. On the effective date of this 
rule (see DATES above), the protections of the Act provided for in the 
4(d) rule for the silverspot will apply to the subspecies wherever it 
is found. We acknowledge that there is uncertainty about the extent of 
suitable habitat within the silverspot's range, and thus it would be 
premature to except take prohibitions for actions in suitable habitats 
where occupancy is unknown until adequate surveys for the butterfly are 
conducted. In the 4(d) rule, we provide exceptions for take for common 
agricultural practices in wet meadow habitats (see ``Provisions of the 
4(d) Rule'' below). Additionally, if anyone has concerns about specific 
agricultural practices in wet meadow habitats that are not identified 
as exceptions in the 4(d) rule, we welcome those discussions and will 
provide information (see FOR FURTHER INFORMATION CONTACT above). 
Therefore, we have not made any changes to the 4(d) rule in response to 
this comment.
    (16) Comment: The NMDA and others recommended developing an 
outreach strategy and materials for private landowners and local 
entities to provide them information on the listing of the silverspot, 
the subspecies' 4(d) rule, and beneficial conservation actions for the 
subspecies (such as protecting bog violets and planting beneficial 
nectar plants).
    Our response: As part of our outreach efforts, we intend to contact 
landowners of known occupied habitat and discuss the silverspot's 
listing and 4(d) rule, as well as beneficial conservation actions for 
the subspecies. We welcome the assistance of the commenters, State and 
Federal agencies, Tribes, nongovernmental organizations, and other 
interested parties with outreach and implementation of conservation and 
recovery actions.

Public Comments

    (17) Comment: One commenter expressed opposition to listing the 
silverspot under the Act because the reasons for population declines 
are lacking and several of the factors influencing viability in the SSA 
report are either not detectable or are unknown. Without an 
understanding of what is causing the presumed population decline, the 
commenter thought it will be nearly impossible to develop a viable 
recovery plan.
    Our response: We summarize the threats to the silverspot in this 
final rule (see ``Summary of Biological Status and Threats'' below). 
While we acknowledge that there are gaps in our understanding of the 
subspecies, listing under the Act will confer protections to the 
silverspot from several of the identified threats to help arrest and 
reverse its decline. When this rule is effective (see DATES above), 
actions authorized, funded, or carried out by Federal agencies that may 
affect the subspecies will require consultations under section 7 of the 
Act in all occupied areas. Prohibitions against take under section 9 of 
the Act will further protect the silverspot from human-caused mortality 
such as continued habitat loss.
    The Act requires us to develop recovery plans for all listed 
species, unless such a plan will not promote the conservation of the 
species. Recovery plans must, to the maximum extent practicable, 
contain objective, measurable criteria that, when met, would lead to 
``delisting,'' that is, removal of the species from the Lists of 
Endangered and Threatened Wildlife and Plants. These recovery plans are 
created following a final determination to list a species as endangered 
or threatened. Recovery plans are non-binding documents intended to 
provide a roadmap for us and our partners on methods of enhancing 
conservation and minimizing threats to listed species, as well as 
measurable criteria against which to evaluate progress towards 
recovery. Recovery criteria and objectives are developed based on the 
information known at that time, and much is learned about a species 
between the time the recovery plan is developed and the time it is 
determined to no longer meet the Act's definition of endangered or 
threatened.
    (18) Comment: One commenter stated that utility corridors maintain 
or create open, early successional areas that support the silverspot's 
needs, and requested that the proposed exception for maintenance of 
other existing structures in the 4(d) rule apply to many common 
electric company operation, maintenance, and modernization (OMM) 
activities that are essentially maintenance of other existing 
structures. The commenter felt that the additional requirement in the 
4(d) rule for those activities to be kept within the confines of 
already disturbed ground was unclear and, depending on how it is 
interpreted and applied in practice, could significantly limit many OMM 
activities. For example, transmission lines often span long distances 
of relatively undisturbed vegetation between the support towers or 
poles. However, electric companies regularly need to conduct OMM 
activities along transmission line rights-of-way (ROWs)

[[Page 11755]]

in the space between towers or poles. The commenter requested the scope 
of this exception be clarified to include OMM activities along entire 
transmission line ROWs rather than limited to previously disturbed 
areas centered on support towers or poles.
    Our response: Maintenance and operation activities and vegetation 
removal along existing transmission line and utility corridors are not 
major factors influencing the silverspot and are not known to 
negatively affect the subspecies (Service 2023, pp. 28-38). Therefore, 
in this final rule, we add to the silverspot's 4(d) rule an exception 
to the take prohibitions for these activities if the activities are 
kept within the confines of existing ROWs. This does not remove the 
requirement for section 7 consultation and appropriate permitting 
processes. Importantly, construction of new transmission lines and 
utility corridors is not an excepted activity under the 4(d) rule.
    (19) Comment: One commenter requested that we revise one aspect of 
the definition of ``reasonable care'' in the silverspot's 4(d) rule. 
The commenter asked that instead of ``ensuring no introduction of'' 
invasive plant species, we revise the 4(d) rule to read, ``minimizing 
the potential to introduce'' invasive plant species.
    Our response: We agree with the commenter that reasonable care to 
control for invasive plant species should be to minimize their 
potential introduction rather than ensure no introduction. We used 
language in the proposed 4(d) rule that was stricter than we intended, 
and because it is not feasible to ensure no introduction of invasive 
plant species, in this final rule, we clarify that statement in the 
4(d) rule in accordance with the commenter's suggestion.
    (20) Comment: One commenter requested listing the silverspot as 
endangered or alternatively strengthening the 4(d) rule. They also 
recommended designating critical habitat. Their reasons are explained 
in greater detail below:
    a. List as endangered: The commenter stated that the silverspot 
faces immediate extinction and climate change should be considered a 
major factor, rather than a minor factor, as it has significant impacts 
to the subspecies' viability as defined in the SSA report. Most 
silverspot populations face very low or low resiliency conditions and 
possess little to no ability to respond to and recover from 
disturbances and the negative effects of climate change, such as 
earlier springs, rising temperatures, less snowpack, and soil-moisture 
drought. The commenter felt that the proposed rule provided no analysis 
or evidence that these very low resiliency populations are currently 
not at risk of extirpation. The commenter suggested that the imminent 
threat of losing half of the silverspot's populations should make the 
subspecies in danger of extinction throughout a significant portion of 
its range, thus warranting an endangered listing. The commenter stated 
that the loss of these populations may occur in 5 years, not the 30 
years identified as the foreseeable future.
    b. Strengthen the 4(d) rule: Alternatively, the commenter requested 
that we develop a more protective 4(d) rule that does not permit year-
round grazing, because it is not scientifically supported and not 
enforceable. The commenter felt that the proposed 4(d) rule gave 
disproportionate weight to inconclusive possible benefits of grazing in 
need of further study over the more conclusive studies establishing 
grazing's detrimental effects to the silverspot's habitat. They 
recommend that the final 4(d) rule should not allow summer grazing, to 
provide for adequate protection and enforcement.
    c. Designate critical habitat: The commenter requested that we 
designate critical habitat for the silverspot because the benefit of 
designation outweighs the threat of collection. As stated in the SSA 
report, collection is not thought to be a current stressor, and 
designation can be done without disclosing silverspot locations. The 
commenter stated that without credible information regarding actual 
collection risk, designating critical habitat is prudent and necessary 
to conserve the silverspot.
    Our response: Climate change is occurring, and there is strong 
scientific support for projections that warming will continue through 
the 21st century (see ``Climate Change'' under Factors Influencing 
Subspecies Viability, below). However, to date, there is only one small 
silverspot population (Archuleta) of the 10 total populations where 
prolonged drought combined with overgrazing is identified as a 
potential contributor to the population's very low resiliency rank 
based on the best available information (Whiteman 2022, pers. comm.; 
Service 2023, pp. 30, 40-41, 57-60). The other nine populations 
currently appear to have an adequate water supply despite existing 
hydrologic alterations, recent droughts, and drier, current climate 
conditions (Bainbridge and Ireland 2022, pers. comm; Service 2023, p. 
30). While current water availability is not a concern, we are 
concerned about future climate effects to the silverspot in combination 
with other threats, and we determined that the subspecies meets the 
Act's definition of a threatened species. For additional explanation as 
to why the species does not meet the Act's definition of an endangered 
species throughout all or a significant portion of its range, see 
``Summary of Biological Status and Threats and Determination of 
Silverspot's Status'' below.
    We find that the 4(d) rule exception for grazing is scientifically 
supported and enforceable. The exception for grazing is based on the 
best available scientific information that light summer grazing (30 
percent or less utilization of forage) and moderate fall and spring 
grazing (40 to 50 percent utilization) appears to be compatible with 
the subspecies' needs and habitat requirements (Arnold 1989, entire; 
Service 2023, pp. 33-34). In practice, little summer grazing occurs in 
silverspot habitat because many landowners move their cattle to higher 
elevations with more seasonal forage (Service 2023, p. 33). While 
livestock grazing under this exception may result in low levels of 
take, these grazing practices do not pose a threat to the silverspot's 
continued existence and should help maintain suitable habitat 
conditions for the subspecies. Additionally, we consider the 
utilization rates for seasonal grazing to provide enforceable and 
objective grazing measurements. We find that the 4(d) rule provides 
flexibility to our partners and satisfies the requirement in section 
4(d) of the Act to issue regulations deemed necessary and advisable to 
provide for the conservation of the silverspot. When this rule is 
effective (see DATES above), we will work with private landowners, 
public land managers, Tribes, and grazing experts to maintain or 
improve silverspot habitat using seasonal grazing practices.
    Finally, the demand for butterflies is high by collectors in the 
illegal animal trade, and the best available information indicates that 
collection may have resulted in the extirpation of one silverspot 
colony (Scott 2023, pers. comm.; Service 2023, p. 31). We believe that 
the public has been largely unaware of the subspecies and that listing 
under the Act will raise public awareness and result in a greater 
demand from collectors. We determine in this final rule that the 
designation of critical habitat is not prudent in accordance with 50 
CFR 424.12(a)(1), because the silverspot faces a threat of unauthorized 
collection and trade, and designation can reasonably be expected to 
increase the degree of this threat to the subspecies. We have 
determined that the publication of maps and

[[Page 11756]]

descriptions outlining the locations of the silverspot would further 
facilitate unauthorized collection and trade, as collectors would know 
the exact locations where silverspots occur (see section III. Critical 
Habitat below).
    For the reasons explained above, we are not making any changes to 
this final rule in response to this comment.
    (21) Comment: Some commenters opposed listing the silverspot and 
stated that the Act does not work for insects and other species that 
cannot accurately be identified. Commenters felt that the silverspot's 
definition and description in the proposed rule was highly ambiguous 
and the SSA report identified almost every color as a characteristic of 
the subspecies. They are concerned about the ability to accurately 
count and distinguish the silverspot from other subspecies with ranges 
that overlap and from potential hybrids that may result from 
reproduction between the silverspot and other subspecies; they are also 
concerned about the environmental factors that may impact the 
silverspot's characteristics. The commenters felt that the Service's 
inability to clearly identify the silverspot will lead to public 
confusion, an erosion of public support, and the assumption that any 
butterfly or moth in the silverspot's range would be treated as a 
listed species. The inability to accurately describe the species falls 
into the category of intrinsic uncertainty as defined by a published 
paper they provided and may not be resolvable (Freckleton 2020, 
entire). The commenters requested to know what has changed since our 
previous determinations that suggested the silverspot was not a 
listable entity.
    Our response: We understand the commenters' questions and 
uncertainty regarding identification and taxonomy. We disagree with the 
comment that the subspecies is not well defined or described, or that 
there is intrinsic uncertainty regarding the taxonomy that cannot be 
resolved. A recent genetic study identified the silverspot as a 
distinct taxon, and we have delineated the subspecies' range based on 
that report (Cong et al. 2019, entire) (see ``Background'' under 
section I. Final Listing Determination below). The silverspot and its 
habitat can be identified accurately by experts or with training, in 
the field or with close-up photographs. There is always the potential 
for hybridization to occur at the margins of a species' range or areas 
of overlapping ranges with other species or subspecies. However, there 
is a low likelihood of interbreeding to produce hybrid butterflies 
within the silverspot's range (Service 2023, pp. 1-14). Any potential 
hybrids can be confirmed through additional genetic analysis, and we 
will address methods to count and estimate butterfly numbers during the 
recovery planning process.
    Our determination in 1996 that removed the designation of the 
silverspot as a category 2 candidate was not related to taxonomy; 
rather, we discontinued the practice of maintaining a list of species 
regarded as category 2 candidates (see 61 FR 7596, February 28, 1996; 
see also ``Previous Federal Actions'' in the May 4, 2022, proposed rule 
(87 FR 26319)). Category 2 candidate species were taxa for which we 
lacked conclusive data on biological vulnerability and threats. By 
2013, we had more information on the silverspot to evaluate its status 
and threats in response to a petition submitted to us by Wild Earth 
Guardians.
    (22) Comment: Commenters asked about the status of potential 
silverspot hybrids under the Act.
    Our response: We address hybrids on a case-by-case basis under the 
Act, and in this case, we did not propose to list hybrids of the 
silverspot because as we describe above in our response to Comment (1), 
there is a low likelihood of finding hybrid butterflies in the 
silverspot's range in the future because the various subspecies of S. 
nokomis are isolated from one another.
    (23) Comment: Some commenters felt that the Service made an 
arbitrary decision when we determined that habitat fragmentation is a 
threat to the silverspot, while pesticide usage is not. The best 
available science for other insect species such as the monarch 
butterfly (Danaus plexippus) identifies pesticide use as a significant 
component of activities that cause habitat fragmentation (e.g., 
agriculture and haying). Commenters also stated that it was not clear 
whether we evaluated habitat fragmentation across the entire range or 
only in known, occupied habitat.
    Our response: The hypothesis that pesticides are a major threat to 
the silverspot presented in this comment appears to be based solely on 
the commenters' evaluation of threats identified for other species. No 
methods or data are given or cited for pesticide use and effects on the 
silverspot or similar species in the arid western United States. 
Evidence in support of such a hypothesis would need to be provided for 
further consideration. We do not discuss pesticides in the May 4, 2022, 
proposed rule or this final rule because our evaluation in the SSA 
report identified it as a minor factor influencing the current and 
future condition of the silverspot (Service 2023, pp. 27-28, 32). The 
primary agricultural practices in the silverspot's range are haying and 
grazing that generally use fewer pesticides than are used on croplands. 
However, we state in the SSA report that further research is needed on 
pesticide use and its effects on the subspecies.
    Based on the best available information, habitat loss and 
fragmentation are primary threats to the silverspot in occupied habitat 
and across the range (see Factors Influencing Subspecies Viability, 
below). Nearly all populations have been or are expected to be 
negatively affected by this threat, which has resulted in lower current 
and future population resiliency and connectivity.
    (24) Comment: Commenters expressed concern that there would be 
significant restrictions placed on recreation as a result of listing 
the silverspot, even though the proposed rule identifies recreation as 
a minimal threat to the silverspot. The commenters were familiar with 
listing decisions for other species (wolverine (Gulo gulo luscus) and 
Mexican spotted owl (Strix occidentalis lucida)) where the Service 
explicitly and clearly states that recreation is not a threat, but 
other agencies placed significant restrictions on recreation because of 
the potential for habitat fragmentation.
    Our response: The silverspot primarily occurs on private lands (18 
of the 21 colonies), where recreation does not occur. Occupied habitat 
on public lands also currently appears to have minimal recreational 
use, and we are not aware of plans that may increase the level of 
future recreational use in these areas. However, recreation could pose 
a threat to the silverspot if trails or other recreational facilities 
are planned in the future within the butterfly's habitat that may 
result in habitat loss or degradation, invasive plant establishment, 
changes to the water regime, or erosion.
    Section 7(a)(2) of the Act requires Federal agencies to ensure that 
activities they authorize, fund, or carry out are not likely to 
jeopardize the continued existence of any endangered or threatened 
species or destroy or adversely modify its critical habitat. When this 
rule is effective (see DATES above), Federal agencies will be required 
to consult with us on the potential effects to the silverspot for all 
proposed projects, including recreation projects, that are subject to 
the requirements of section 7(a)(2) of the Act. For proposed projects 
without a Federal nexus, the proponent must ensure that the project 
will not result in take of the silverspot as set forth in the

[[Page 11757]]

4(d) rule. We will cooperate with Federal agencies, landowners, and 
project proponents to identify conservation measures that avoid or 
minimize effects and take of the silverspot during project planning.

I. Final Listing Determination

Background

    A thorough review of the taxonomy, life history, and ecology of the 
silverspot is presented in the SSA report (Service 2023, pp. 9-27), and 
is briefly summarized here.
    The silverspot is a relatively large butterfly with up to a 3-inch 
wingspan. Males typically have bright orange on the upper side of the 
wing, while females typically have cream or light yellow with brown or 
black. The underside of the wing of both sexes has silvery-white spots, 
giving the subspecies' the common name of silverspot butterfly.
    Based on recent genetic analysis, there are 10 major populations of 
Speyeria nokomis comprised of five subspecies throughout the United 
States and Mexico (Cong et al. 2019, entire). We established a new, 
more precise range boundary for the subspecies that is the subject of 
this document, the silverspot (S. n. nokomis), in the SSA report based 
on the genetic analysis, which limits the distribution to east-central 
Utah through western and south-central Colorado and into north-central 
New Mexico (Service 2023, p. 18). The new range delineation shows that 
the subspecies does not occur in the Great Basin and thus the former 
common name, Great Basin silverspot butterfly, is no longer valid. 
Consequently, we refer to the S. n. nokomis subspecies as 
``silverspot'' in this final rule.
    In the SSA report, we identified 10 populations of silverspot in 
our analysis, consisting of the following: Archuleta, Conejos, 
Costilla, Garfield, La Plata, Mesa/Grand, Montrose/San Juan, and Ouray 
populations in Colorado and Utah; and the San Miguel/Mora and Taos 
populations in New Mexico (Service 2023, figure 14 and table 4, pp. 39-
47). Populations of silverspot occur between 5,200 feet (ft) (1,585 
meters (m)) and 8,300 ft (2,530 m). The butterfly requires moist 
habitats in mostly open meadows with a variety of herbaceous and woody 
vegetation. Eggs are laid on or near the bog violet (Viola 
nephrophylla/V. sororia var. affinis), which the larvae feed on 
exclusively. A variety of flowering plants provide adult nectar 
sources. The butterfly completes its entire life cycle in one year.

Regulatory and Analytical Framework

Regulatory Framework

    Section 4 of the Act (16 U.S.C. 1533) and the implementing 
regulations in title 50 of the Code of Federal Regulations set forth 
the procedures for determining whether a species is an endangered 
species or a threatened species, issuing protective regulations for 
threatened species, and designating critical habitat for endangered and 
threatened species. In 2019, jointly with the National Marine Fisheries 
Service, the Service issued a final rule that revised the regulations 
in 50 CFR part 424 regarding how we add, remove, and reclassify 
endangered and threatened species and the criteria for designating 
listed species' critical habitat (84 FR 45020; August 27, 2019). On the 
same day, we issued a finalrule that revised 50 CFR 17.31 and 17.71(84 
FR 44753; hereinafter, ``the 20194(d) rule'') and ended the ``blanket 
rule'' option for application of section 9prohibitions to species newly 
listed as threatened after the effective date ofthose regulatory 
revisions (September 26, 2019). Blanket rules hadextended the majority 
of the protections (all of the prohibitions that apply to endangered 
species under section 9 and additional exceptions to the prohibitions) 
to threatened species, unless we issued an alternative rule under 
section 4(d) of the Act for a particular species (i.e., a species-
specific 4(d) rule).The blanket rule protectionscontinued to apply to 
threatened speciesthat were listed prior to September 26,2019, without 
an associated species-specificrule. Under the 2019 4(d) rule,the only 
way to apply protections to aspecies newly listed as threatened is 
forus to issue a species-specific rule settingout the protective 
regulations that areappropriate for that species.
    Our analysis for this decision applied our current regulations, 
portions of which were last revised in 2019. Given that we proposed 
further revisions to these regulations on June 22, 2023 (88 FR 40742; 
88 FR 40764), we have also undertaken an analysis of whether the 
decision would be different if we were to apply those proposed 
revisions. We concluded that the decision would have been the sameif we 
had applied the proposed 2023 regulations. The analyses under both the 
regulations currently in effect and the regulations after incorporating 
the June 22, 2023, proposed revisions are included in our decision 
file.
    The Act defines an ``endangered species'' as a species that is in 
danger of extinction throughout all or a significant portion of its 
range, and a ``threatened species'' as a species that is likely to 
become an endangered species within the foreseeable future throughout 
all or a significant portion of its range. The Act requires that we 
determine whether any species is an endangered species or a threatened 
species because of any of the following factors:
     Factor A--The present or threatened destruction, 
modification, or curtailment of its habitat or range;
     Factor B--Overutilization for commercial, recreational, 
scientific, or educational purposes;
     Factor C--Disease or predation;
     Factor D--The inadequacy of existing regulatory 
mechanisms; or
     Factor E--Other natural or manmade factors affecting its 
continued existence.
    These factors represent broad categories of natural or human-caused 
actions or conditions that could have an effect on a species' continued 
existence. In evaluating these actions and conditions, we look for 
those that may have a negative effect on individuals of the species, as 
well as other actions or conditions that may ameliorate any negative 
effects or may have positive effects.
    We use the term ``threat'' to refer in general to actions or 
conditions that are known to or are reasonably likely to negatively 
affect individuals of a species. The term ``threat'' includes actions 
or conditions that have a direct impact on individuals (direct 
impacts), as well as those that affect individuals through alteration 
of their habitat or required resources (stressors). The term ``threat'' 
may encompass--either together or separately--the source of the action 
or condition or the action or condition itself.
    However, the mere identification of any threat(s) does not 
necessarily mean that the species meets the statutory definition of an 
``endangered species'' or a ``threatened species.'' In determining 
whether a species meets either definition, we must evaluate all 
identified threats by considering the species' expected response and 
the effects of the threats--in light of those actions and conditions 
that will ameliorate the threats--on an individual, population, and 
species level. We evaluate each threat and its expected effects on the 
species, then analyze the cumulative effect of all threats on the 
species as a whole. We also consider the cumulative effect of the 
threats in light of those actions and conditions that will have 
positive effects on the species, such as any existing regulatory 
mechanisms or conservation efforts. The Secretary determines whether 
the species meets the definition

[[Page 11758]]

of an ``endangered species'' or a ``threatened species'' only after 
conducting this cumulative analysis and describing the expected effect 
on the species now and in the foreseeable future.
    The Act does not define the term ``foreseeable future,'' which 
appears in the statutory definition of ``threatened species.'' Our 
implementing regulations at 50 CFR 424.11(d) set forth a framework for 
evaluating the foreseeable future on a case-by-case basis. The term 
``foreseeable future'' extends only so far into the future as the 
Service can reasonably determine that both the future threats and the 
species' responses to those threats are likely. In other words, the 
foreseeable future is the period of time in which we can make reliable 
predictions. ``Reliable'' does not mean ``certain''; it means 
sufficient to provide a reasonable degree of confidence in the 
prediction. Thus, a prediction is reliable if it is reasonable to 
depend on it when making decisions.
    It is not always possible or necessary to define the foreseeable 
future as a particular number of years. Analysis of the foreseeable 
future uses the best scientific and commercial data available and 
should consider the timeframes applicable to the relevant threats and 
to the species' likely responses to those threats in view of its life-
history characteristics. Data that are typically relevant to assessing 
the species' biological response include species-specific factors such 
as lifespan, reproductive rates or productivity, certain behaviors, and 
other demographic factors.

Analytical Framework

    The SSA report documents the results of our comprehensive 
biological review of the best scientific and commercial data regarding 
the status of the subspecies, including an assessment of the potential 
threats to the subspecies. The SSA report does not represent our 
decision on whether the subspecies should be listed as an endangered or 
threatened species under the Act. However, it does provide the 
scientific basis that informs our regulatory decisions, which involve 
the further application of standards within the Act and its 
implementing regulations and policies.
    To assess the silverspot's viability, we used the three 
conservation biology principles of resiliency, redundancy, and 
representation (Shaffer and Stein 2000, pp. 306-310). Briefly, 
resiliency is the ability of a species to withstand environmental and 
demographic stochasticity (for example, wet or dry, warm or cold 
years); redundancy is the ability of a species to withstand 
catastrophic events (for example, droughts, large pollution events); 
and representation is the ability of a species to adapt to both near-
term and long-term changes in its physical and biological environment 
(for example, climate conditions, pathogens). In general, species 
viability will increase with increases in resiliency, redundancy, and 
representation (Smith et al. 2018, p. 306). Using these principles, we 
identified the silverspot's ecological requirements for survival and 
reproduction at the individual, population, and subspecies levels, and 
described the beneficial and risk factors influencing the subspecies' 
viability.
    The SSA process can be categorized into three sequential stages. 
During the first stage, we evaluated the individual subspecies' life-
history needs. The next stage involved an assessment of the historical 
and current condition of the subspecies' demographics and habitat 
characteristics, including an explanation of how the subspecies arrived 
at its current condition. The final stage of the SSA report involved 
making predictions about the subspecies' responses to positive and 
negative environmental and anthropogenic influences. Throughout all of 
these stages, we used the best available information to characterize 
viability as the ability of a species (or in this case, subspecies, 
which is a listable entity under the Act) to sustain populations in the 
wild over time. We use this information to inform our regulatory 
decision. The following is a summary of the key results and conclusions 
from the SSA report; the full SSA report can be found at Docke