[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:
    <bullet> Factor A--The present or threatened destruction, 
modification, or curtailment of its habitat or range;
    <bullet> Factor B--Overutilization for commercial, recreational, 
scientific, or educational purposes;
    <bullet> Factor C--Disease or predation;
    <bullet> Factor D--The inadequacy of existing regulatory 
mechanisms; or
    <bullet> 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 Docket No. 
FWS-R6-ES-2021-0134 on https://www.regulations.gov.

Summary of Biological Status and Threats

    In this discussion, we review the biological condition of the 
silverspot and its resources, and the threats that influence the 
subspecies' current and future condition, to assess the subspecies' 
overall viability and the risks to that viability.

Individual Needs

    Individual silverspot needs include wet meadows supported by 
springs, seeps, streams, or irrigated areas that contain the bog violet 
host plant for eggs and larvae, and other herbaceous vegetation for 
cover and food resources. The butterflies may benefit from a light 
interspersion of willow or other shrubs for shade and for larval 
shelter. More dense willow and shrubs often surround open meadows where 
the silverspot occurs and, if the woody vegetation does not take over 
the meadows, the margins of denser stands can be beneficial for shade 
and shelter as well.

Population Needs

    Populations need abundant individuals within habitat patches of 
adequate size and quality to maintain survival and reproduction. In 
general, the greater the suitable habitat acreage, and the greater the 
number of individuals within a population, the greater the resilience. 
Furthermore, colonies and populations need to be close enough to each 
other for individuals to breed with each other to maintain genetic 
diversity. The silverspot likely does not fly more than 5-10 miles (mi) 
(8-16 kilometers (km)) and would likely have difficulty finding another 
colony beyond this distance (Ellis 2020c, 2020d, 2020e, pers. comms.). 
Additionally, the silverspot needs the bog violet to be of sufficient 
extent and density to support colonies and populations. We define 
colonies to mean areas of abundant violets that produce butterflies, as 
well as surrounding habitat with nectar plants. If there is narrow but 
contiguous nectar habitat up or down a drainage but without violets (or 
with only sparse violets), we consider those areas transitional 
corridors that are likely valuable for dispersal and genetic 
connectivity.
    The silverspot and other S. nokomis subspecies can move between 
colonies within a continuous or nearly continuous riparian zone (Arnold 
1989, pp. 10, 14; Fleishman et al. 2002, p. 708). For example, six 
colonies occurred along a 5-mile stretch in Unaweep Canyon that had 
likely genetic interchange (Ellis 1989, p. 3). However, these are 
considered separate colonies due to the natural or human-caused 
patchiness of bog violets up and down the canyon. In a mark-recapture 
study (Arnold 1989, pp. 10, 14, 21) in Unaweep Canyon, about 50 percent 
of the recaptured butterflies moved between two colonies separated by 
about 0.75 mi (1.2 km). Based on this work, the researcher inferred 
that the silverspot could easily move at least 1 mile, and based on 
this, Ellis (1989, p. 19) further inferred that there was exchange of 
individuals among all the Unaweep Canyon colonies every 1 to 5 years. 
This information provided the basis for Ellis' professional judgement 
that colonies or populations farther than 5 to 10 mi (8 to 16 km) from 
each other are likely isolated (Ellis 2020c, 2020d, 2020e, pers. 
comm.).
    Some silverspot populations are comprised of a single colony, while

[[Page 11759]]

others are comprised of multiple colonies that function as a 
metapopulation. Within a metapopulation, butterflies are close enough 
to move between colonies and to interbreed and can recolonize 
temporarily extirpated areas that may result from local, naturally 
occurring (stochastic) events. For instance, a flood may extirpate a 
colony, but if there are nearby colonies, the temporarily flooded area 
may return to suitable habitat conditions and be recolonized by the 
silverspot.
    Unfortunately, there is very little information on what an 
adequate-sized habitat patch is, especially if there is only a single 
colony in a population. A professional estimate for minimum patch size 
of colonies is 2 acres (ac) (0.8 hectares (ha)) if the habitat has a 
reliable groundwater source and has high violet density and is 5 ac (2 
ha) if violets are less dense due to natural or human-caused 
variability within a patch (Ellis 2020e, pers. comm.). Although it is 
possible a single 2-ac or 5-ac patch of habitat could support the 
butterfly for a period of time, a more resilient metapopulation will 
likely contain at least three colonies of those patch sizes or greater. 
A three-colony metapopulation will have a better chance of survival by 
spreading the risk of extirpation if a natural event occurs at one or 
two of the colonies. Thus, the remaining one or two colonies can 
recolonize the extirpated sites assuming suitable habitat remains or 
reestablishes. Due to natural variability in soil and topographic 
conditions, we assume that most areas within the silverspot's range are 
likely to have a lower density of violets, rather than dense violets 
(Service 2023, pp. 23-25). Consequently, under this assumption, a 
minimum amount of habitat for a sufficiently resilient population may 
be 12 ac (5 ha), and this can be made up of multiple colonies if they 
are at least 2 ac (0.8 ha) in size (Service 2023, p. 25). The specific 
minimum threshold for single colonies to maintain viability is unknown, 
but the larger the acreage the greater the resiliency and higher 
likelihood of viability.
    There is also little information on the minimum number of 
silverspot individuals needed to sustain a colony. There have only been 
two demographic studies for the silverspot that occurred at the same 
locations 10 years apart: 1979 and 1989 (Arnold 1989, entire). The 1989 
study found a daily estimate of between 48 and 260 butterflies with two 
different models at the Unaweep Seep colony (Arnold 1989, pp. 6, 14). A 
combined population estimate at the Unaweep Seep colony and another 
upstream colony in Unaweep Canyon (which is considered two colonies due 
to intervening transitional habitat) resulted in a range of daily 
abundance from 594 to 2,689 butterflies.
    Quality of habitat may have as much weight in determining 
resiliency of a colony or population as does overall size of a habitat 
patch or number of individuals. Habitat quality could potentially be 
measured by density of violets. The Unaweep Seep study (Arnold 1989, p. 
20) revealed that the larger colony with many individuals became 
extirpated, likely due to vegetative encroachment, while the upstream 
colony with more violets remained extant. Consequently, populations 
appear to have greater chance for survival when containing more 
violets.
    Based on observations of grazed and burned properties in Unaweep 
Canyon, occasional or well-managed grazing and burning likely benefit 
the violet by reducing willows, as well as reducing thatch buildup from 
grasses and sedges (Arnold 1989, p. 14; Ellis 1989, pp. 18, 19). 
Consequently, natural factors or management activities that lead to 
early seral stages or at least more open conditions, where willow, 
grass, sedge, or other vegetation does not outcompete violets, is 
important to colonies and populations.
    Based on the scant evidence, the minimum number of individuals that 
are needed to sustain a silverspot colony or population is unknown, and 
even apparent natural but detrimental habitat factors, such as 
excessive growth of other plants, can cause extirpation of seemingly 
large colonies. Without additional study, it is not known what the 
minimum habitat size is to maintain viability, nor what density or 
abundance of bog violets or nectar plants is needed to sustain a colony 
or population, nor the maximum distance between colonies or populations 
that can be reached for genetic interchange to continue to occur on a 
regular basis. Furthermore, it is unknown if large single-colony 
populations can be sufficiently resilient without occasional genetic 
interchange from other populations.
    In summary, to be adequately resilient, silverspot populations need 
water to sustain violets for the larvae, as well as occasional or 
seasonal disturbance by grazing from native ungulates or domestic 
livestock, or burning, mowing, or non-catastrophic flooding, to 
occasionally remove vegetation that might otherwise crowd out the 
violets and other nectar plants for the adults. Furthermore, based on 
expert opinion and evidence, the most resilient populations need to be 
at least 2 ac (0.8 ha) in size with dense violets or at least 5 ac (2 
ha) in size with less dense violets (Ellis 2020e, pers. comm.), and 
need to have a few to several colonies within 0.75 to 5 mi (1.2 to 8 
km) of each other and likely be not more than 10 mi (16 km) from each 
other (Arnold 1989, pp. 10, 14; Ellis 1989, p. 19; Ellis 2020c, 2020d, 
2020e pers. comm.).

Subspecies Needs

    To maintain viability, the silverspot needs to have a sufficient 
quality and quantity of habitat for adequately resilient populations, 
numerous populations to create redundancy in the event of catastrophic 
events, and broad enough genetic and ecological diversity to adapt to 
changing environmental conditions (representation). The subspecies will 
have a better chance of long-term viability if single-colony 
populations and even the metapopulations occasionally receive 
individuals from other populations such that genetic interchange 
occurs, better enabling them to adapt to environmental changes.

Factors Influencing Subspecies Viability

    We reviewed the potential risk factors (i.e., threats, stressors) 
that could be affecting the silverspot now and in the future. In this 
final rule, we will discuss only those factors in detail that could 
meaningfully impact the status of the subspecies. Habitat loss and 
fragmentation, human-caused hydrologic alteration, livestock grazing, 
genetic isolation, exotic plant invasion, climate change, climate 
events, larval desiccation, and collecting are all factors that 
influence or could influence the subspecies' viability. Those risks 
that are not known to have effects on silverspot populations, such as 
disease, predation, prescribed burning or wildfire, and pesticides, are 
not discussed here but are evaluated in the SSA report.
Habitat Loss and Fragmentation
    Habitat loss from golf course and housing development caused the 
extirpation of two historical colonies north of Durango, Colorado 
(Selby 2007, entire; Ellis and Fisher 2020, pers. comm.). The remaining 
colony in the La Plata population has residential and commercial 
development across the street from it, and one of two drainages 
supplying water to it has relatively new housing and golf courses 
within 1.5 air miles (2.4 km), potentially degrading downstream 
silverspot habitat through hydrologic alteration. Housing development 
also appears to have been

[[Page 11760]]

a contributing factor in extirpation of the Beulah, New Mexico, colony 
(Scott and Fisher 2014, p. 3). In Colorado, it is possible that Rifle 
Gap Reservoir and Dam degraded and fragmented habitat, as one butterfly 
was sighted at a small wetland downstream of the dam and the reservoir 
flooded and fragmented habitat upstream. Additional habitat alteration 
upstream and downstream from a variety of factors (residential and 
commercial development, roads, and agricultural conversion of habitat) 
also has likely fragmented habitat. Many other colonies and populations 
have development around them that also either directly encroaches on 
the habitat or likely has caused degradation and fragmentation from 
homes, roads, hydrologic alteration, and habitat conversion.
    Agricultural habitat conversion can cause loss or fragmentation of 
habitat and typically involves mowing native meadows or growing exotic 
grasses for hay. Aerial imagery reveals that agricultural conversion 
has been extensive within the silverspot's range. It has likely caused 
loss of unknown colonies over the last 150 years and has fragmented 
native habitat, reducing connectivity between colonies and populations. 
Annual haying may be less detrimental than haying two or three times a 
summer. One major population of Speyeria nokomis (Chuska Mountains) in 
Arizona and New Mexico has persisted for many years even though haying 
occurs there once a year typically in late August or September (Cong et 
al. 2019, entire; Smith 2019, pers. comm.).
    Despite the silverspot's potential compatibility with annually 
mowing native hay fields, agricultural conversion to unsuitable crops 
or fragmentation of habitat in the silverspot's range has been 
extensive. Furthermore, the impact of residential and commercial 
development, and other development like roads, continues to limit and/
or degrade habitat in or adjacent to existing colonies and populations. 
Habitat loss and fragmentation, therefore, has meaningfully reduced the 
viability of the subspecies.
Hydrologic Alteration
    Hydrologic alteration is also a factor influencing the subspecies' 
viability. Hydrologic alteration can result from a variety of sources, 
including, but not limited to, diversions for agricultural and domestic 
use; erosion and stream channel incision caused by livestock grazing, 
mining, roads, or dredging and filling of wetlands; removal of beaver 
dams; manipulation of waterways that minimizes flooding and reduces 
natural meander features; and creation and operation of large human-
made dams. For example, the only colony in the Costilla population has 
a diversion ditch running through it that likely reduced the size of 
colony. The ditch and other diversions have allowed for extensive 
agricultural development in the drainage that has altered native 
habitat and likely dropped the water table in much of the area. The 
Montrose County colony in the Montrose/San Juan population also has had 
livestock grazing and water diversions occur over the last 30 years, 
which have degraded the quality of the wet meadow areas and lowered the 
water table (Ireland 2018, pers. comm.).
    Many drainages in the Sacramento Mountains, where one historical 
silverspot colony may have occurred, succumbed to incision of streams 
around 1900, in turn lowering water tables and eliminating wet meadow 
habitat (Service 2023, p. 35). Incision of stream channels occurred due 
to erosion from deforestation, conversion to agricultural and grazing 
lands, mining, and so forth. Beavers were also eliminated around 1900 
in the Sacramento Mountains (and other parts of the West), which also 
undoubtedly caused reduction of water tables and elimination of wet 
meadow habitat suitable for the silverspot and other wetland-dependent 
species. Hydrologic alteration that degrades riparian areas and lowers 
water tables from natural systems has occurred not only in the Costilla 
population, Montrose/San Juan population, and Sacramento Mountains, but 
extensively in the western United States, including much of the 
silverspot's range. Hydrologic alteration continues to limit suitable 
habitat and is a major factor influencing the viability of the 
subspecies.
Livestock Grazing
    Grazing is ongoing in suitable habitat for the subspecies and is a 
major factor influencing the subspecies' viability. Livestock grazing 
may cause habitat loss and degradation if excessive, especially in the 
naturally scarce habitats of the silverspot (Hammond and McCorkle 1983, 
p. 219) and depending on the timing and intensity. Year-round grazing 
or heavy summer grazing is typically incompatible with the silverspot 
because livestock graze on the violet leaves, nectar sources, and other 
vegetation necessary for the butterfly when the larvae and adults need 
them (Ellis 1999, p. 5). For example, an area adjacent to a colony in 
the Ouray population has underlying hydrology and soils beneficial for 
the silverspot, but the habitat is unsuitable due primarily to grazing 
and perhaps to a lesser extent occasional mowing for hay (Service 2023, 
figure 13, p. 34).
    Livestock grazing benefits and is compatible with silverspot 
conservation if managed appropriately. Winter grazing is beneficial to 
maintain the bog violet and suitable habitat conditions. Light or 
moderate summer grazing (up to 20 or 30 percent vegetative utilization) 
appears to be acceptable (Arnold 1989, p. 14), but total rest from 
grazing in the summer is preferred (Ellis 2020g, pers. comm.). If one 
or more kinds of vegetation are too dense, they can prevent the bog 
violet from persisting and thus cause extirpation of the silverspot. 
This occurred in the Unaweep Seep colony in the Mesa/Grand population, 
perhaps primarily because of spike rush (Eleocharis spp.) invasion of 
meadows but also seemingly because of grass, sedge, and willow invasion 
(Arnold 1989, pp. 9, 14; Ellis 1999, pp. 3, 5, 6). It is unknown if 
this invasion would have occurred without grazing or if long-term 
grazing was the factor that shifted vegetation. Without occasional 
reduction or removal, herbaceous or woody vegetation could crowd out 
violets. Seasonal grazing or mowing and 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).
Genetic Isolation
    Population isolation can cause detrimental genetic and demographic 
effects and is a concern for the silverspot's population resiliency as 
well as its redundancy and representation. Lower levels of genetic 
diversity can reduce the capacity of a population to respond to 
environmental change (representation) and may lead to reduced 
population fitness through reductions in individual longevity and 
fecundity (i.e., fewer offspring) and smaller population sizes (Darvill 
et al. 2006, p. 608). Another silverspot subspecies, S. n. apacheana, 
has low genetic diversity, likely from genetic drift (loss of alleles 
(versions of a gene) or change in their frequency in a population) due 
to genetic isolation and small population size (Britten et al. 1994, 
entire). Genetic exchange between and within populations can alleviate 
problems with genetic drift and augment populations demographically. In 
S. n. apacheana, routine dispersal distances up to 2.5 mi (3.9 km) were 
documented, and 26 percent of the

[[Page 11761]]

recaptured butterflies had emigrated from the initial patch of capture 
(Fleishman et al. 2002, p. 708). This migration appears to play an 
important role for S. n. apacheana populations both demographically and 
genetically (Britten et al. 2003, p. 232). Consequently, the ability or 
inability of individuals to migrate between colonies and populations is 
expected to also be of benefit or detriment, respectively, for the 
silverspot.
    Genetic isolation among silverspot populations indicates reduced 
population fitness and could be of concern in the future (Cong et al. 
2019, p. 22). Based on the latest scientific evidence, genetic exchange 
does not appear to occur between colonies or populations that are at 
least 20 miles apart (Cong et al. 2019, entire). Currently, the 
distance between the two closest populations, which we know are 
genetically different and represent separate populations, is 24.5 air 
miles (39 km) (between the Taos and San Miguel/Mora populations in New 
Mexico). Consequently, and more specifically, the distance where 
silverspot populations may not interbreed and thus may not support each 
other genetically or demographically appears to be somewhere between 20 
and 24.5 air miles (32 and 39 km). We used the minimum distance of 20 
mi (32 km), based on findings of Cong et al. (2019, entire), in our 
analysis of genetic connectivity (see Current Condition, below).
    Reasons for isolation, specifically whether from natural 
fragmentation or human habitat alteration, are not currently known for 
all populations. It is also not known how long single colonies may have 
been isolated from each other. If an isolated colony has enough area of 
habitat to support large numbers of the butterfly, it may be resilient 
enough to survive without nearby colonies and thus maintain viability 
for a long time. However, many silverspot populations, whether single-
colony or multi-colony, have limited amounts of habitat. It is unknown 
specifically how long it will take for low genetic diversity to become 
a threat to the silverspot, but isolation of populations indicates that 
loss of genetic diversity could be a threat at some point, if loss of 
populations through lack of demographic support does not occur first, 
and both are cause for concern for the subspecies' viability.
Exotic Plant Invasion
    The Taos population has experienced some invasion by the exotic 
Siberian elm (Ulmus pumila). Because Siberian elm is widespread in the 
silverspot's range, we expect its occurrence to increase if changes in 
climate reduce snowpack and water levels in the wet meadows of the Taos 
population or other populations. Similarly, the extirpated Unaweep Seep 
colony location was invaded by other exotic species, including 
Himalayan blackberry (Rubus armeniacus) and tree-of-heaven (Ailanthus 
altissima). Although not known to occupy other colonies at present, 
these plant species could invade other colonies (Plank 2020, pers. 
comm.). Other exotic woody or herbaceous species (such as Russian olive 
(Elaeagnus angustifolia), tamarisk (Tamarix spp.), or leafy spurge 
(Euphorbia esula)) can rapidly take over habitat and could eliminate 
bog violets and other native plants. However, there is currently little 
to no data on plants at the colonies (Ellis 1989, pp. 14-15).
    Some nonnative thistles, such as Canada thistle (Cirsium arvense), 
occur in or around colonies and can create monocultures that create 
poor overall habitat conditions for the silverspot and bog violet by 
replacing native species (Ellis 1989, p. 14; Selby 2007, p. 30). Land 
managers in the West sometimes control the spread of exotic thistles, 
but Canada thistle (as well as native thistles) provides a nectar 
source for the silverspot. Additionally, the adventive (exotic but not 
well-established) bull thistle (C. vulgare) and burdock (Arctium minus) 
can provide nectar sources (Ellis 1989, p. 14). Because the silverspot 
uses exotic thistles, aggressive control of them has been advised 
against (Fisher 2020e, pers. comm.). It does not appear that 
monocultures of Canada thistle or other exotic vegetation have replaced 
native vegetation beneficial for the silverspot at observed colonies 
(Ireland 2018, pers. comm.), but study of plant composition at all 
colonies is needed to determine levels of exotic plant presence. Exotic 
plant invasion is currently considered a minor factor because exotic 
species are not currently known to be significantly influencing the 
subspecies' viability.
Climate Events
    Climate events are defined in the SSA report as events that would 
happen within the range of normal variability (i.e., stochastic 
events). However, they may reduce the amount and quality of habitat and 
the number of butterflies. A record of other Speyeria in Utah indicates 
that too much rain can reduce the number of butterflies but may be 
beneficial to violets, which can support greater numbers of butterflies 
in following years (Myrup 2020b, pers. comm.). Similarly, floods may at 
least temporarily reduce the amount and quality of habitat and 
vegetation as well as butterfly numbers by inundating the area with 
water for long periods or by erosion. For instance, the Lake Fork River 
in northeast Utah flooded in the spring of 2019 and caused the 
reduction or extirpation of a related silverspot subspecies colony in 
the Uinta Mountains documented the year before (Ellis 2019, pers. 
comm.). However, the flood event was not outside the norm for past 
observed flood events in that drainage. This stochastic event provides 
an example of normal climate events that can cause reduction in numbers 
of individual butterflies or temporary extirpation of a colony but are 
not expected to cause permanent reduction or extirpation. Thus, climate 
events are not expected to reduce the subspecies' viability in the long 
term and are considered a minor factor influencing the subspecies' 
viability.
Climate Change
    The climate within the silverspot's range already appears to be 
changing because of increased greenhouse gas emissions, with earlier 
springs and warmer temperatures. Average temperatures in Colorado have 
increased by 2.5 [deg]F (1.4 [deg]C) in the last 50 years (Lukas et al. 
2014, p. 2). Snowpack, as measured by snow water equivalent, has mostly 
been below average in Colorado since 2000. The timing of snowmelt and 
peak runoff has also shifted 1 to 4 weeks earlier in the last 30 years 
in Colorado. Furthermore, the Palmer Drought Severity Index has shown 
an increasing trend in soil-moisture drought conditions due to below 
average precipitation since 2000 and the warming trend (Lukas et al. 
2014, p. 2). More recent analysis using National Oceanic and 
Atmospheric Administration (NOAA) temperature data shows that, since 
1895, the average temperature in much of the northern half of the 
silverspot's range has increased by 3.6 [deg]F (2 [deg]C) or more, and 
it is reported that average annual flows in the Colorado River Basin 
have declined by 20 percent over the past century (Eilperin 2020, 
entire). However, tree ring and other paleoclimate data indicate that 
there were more severe and sustained droughts prior to recent climate 
data (since 1900) (Lukas et al. 2014, pp. 2, 3). The silverspot has 
survived through the more severe past droughts, and, despite noted 
changes in climate over the last 36 years, climate has thus far not 
been a detectable factor in reduction of the subspecies' viability. 
Consequently, at the present and for the current condition analysis in 
the SSA report,

[[Page 11762]]

climate change is considered a minor factor. However, climate may 
become a major factor; see additional discussion of climate change 
under Future Condition, below.
Desiccation of Larvae
    Desiccation of overwintering larvae may be a stressor if soil 
moisture and air humidity are too low or if larvae cannot remain 
hydrated. Soil moisture and dead vegetation, along with some air flow, 
may provide suitable conditions that prevent desiccation (Fisher 2020b, 
2020f, pers. comm.). Hydration also appears to be needed prior to first 
instar larvae overwintering and is achievable if water for drinking is 
freely available and if soil or air moisture is sufficient for 
absorption (Myrup 2020a, pers. comm.; Stout 2020, entire). Snow cover 
may also provide some desiccation prevention and thermal cover, 
although it may not be a significant factor (Ellis 2020a, 2020b, pers. 
comm.). Snow cover may be of benefit during extreme cold (Fisher 2020b, 
pers. comm.). In general, however, extreme cold in the silverspot's 
range is preceded by snow; thus, extreme cold may kill some larvae but 
is likely not a major factor that reduces the subspecies' viability.
Collecting
    Collecting has occurred in silverspot colonies, and it is possible 
collecting in small colonies could negatively affect population 
resiliency (Ellis 1989, p. 15; Selby 2007, p. 31; Scott 2023, pers. 
comm.). We know of one colony that was extirpated, in part, from 
collection by multiple people (Scott 2023, pers. comm.). However, 
collecting is not currently thought to be a significant stressor for 
the silverspot because most colonies occur on private land, colony 
locations are largely unknown to the public, and current collecting 
pressure is not thought to be extensive (Ellis 2020f, pers. comm.). In 
terms of the effect on the current condition of the subspecies, 
collecting is currently considered a minor factor and does not appear 
to be significantly reducing the subspecies' viability. Efforts should 
be taken to keep it a minor factor, as losing even one of the remaining 
populations to collection could have a substantial impact on the 
subspecies' redundancy and representation. We are concerned about the 
potentially detrimental effects to the subspecies' viability from 
future collection if silverspot locations, especially the locations of 
smaller populations, are made public (see section III. Critical Habitat 
below).

Current Condition

    We assessed current conditions of silverspot populations in 
relation to the ecological requirements of this subspecies. 
Measurements available that are consistent across populations are 
habitat patch size, number of colonies, and approximate distance 
between colonies within a population from which genetic connectivity 
can be estimated. Additionally, the presence and potential influence of 
the three major habitat factors affecting the subspecies (habitat loss 
and fragmentation, livestock grazing, and hydrologic alteration) were 
derived from aerial imagery and/or on-the-ground knowledge. Therefore, 
we used these metrics to characterize the current resiliency condition 
of populations (see the SSA report's section 3.5 ``Current Condition by 
Population'' on how metric scores were derived; Service 2023, pp. 39-
40).
    Resiliency scores and categories were established based on the best 
available information and professional opinion of species experts. 
Habitat patch sizes are estimates based on expert opinion of individual 
colony bog violet areas and primary nectar plant areas using aerial 
imagery or field observations. Determination of the number and status 
of colonies within a population was primarily based on expert input and 
survey information.
    There are 10 silverspot populations comprised of 21 known colonies. 
Two populations, Archuleta and Garfield, were not included in the 
genetic analysis by Cong et al. (2019, entire) due to a lack of 
samples, but we consider them to be part of the silverspot subspecies 
due to their geographic proximity to confirmed populations. We 
designated the Archuleta and Garfield populations as separate 
populations because they are more than 20 air miles (32 km) away from 
other populations (41 and 80 mi (66 and 129 km), respectively) and it 
is likely populations more than 20 mi (32 km) apart are not genetically 
connected (Ellis 2020c, 2020d, 2020e, pers. comm.; Grishin 2020b, pers. 
comm.)
    Within the range of and among all 10 populations, five previously 
known colonies have been extirpated; one was confirmed as extirpated 
from the Ouray population as recently as 2022 (Fisher 2022b, pers. 
comm.). The other four extirpations occurred over the last 40 years 
(since the late 1970s) (Scott and Fisher 2014, p. 3; Service 2023, pp. 
18-19). Not including the extirpated colonies or stray sightings, and 
based on recent surveys or expert input, we evaluated the 21 known 
colonies that make up the 10 populations. There is some uncertainty 
whether all 21 colonies are extant based on the lack of consistent and 
consecutive surveys over the last 5 years. We characterize their 
current status in the SSA report as extant, likely extant, unknown, 
likely extirpated, or extirpated (Service 2023, pp. 40, 47).
    Resiliency for each population was scored using metrics for 
population size (in acres), number of colonies within populations, 
connectivity within populations, and habitat condition. Resiliency 
scores are categorized as follows: 0 = predicted extirpation (future 
scenarios only); 1 = very low resiliency; 2 and 3 = low resiliency; 4 
to 6 = moderate resiliency; and 7 and above = high resiliency (see 
table 1, below). According to our current condition analysis in the SSA 
report, three populations have very low resiliency, three populations 
have low resiliency, two populations have moderate resiliency, and two 
populations have high resiliency (see table 1, below; Service 2023, pp. 
46-49).

                    Table 1--Current Condition Resiliency Rankings for Silverspot Populations
----------------------------------------------------------------------------------------------------------------
                                                                                                    Population
                           Population                               Size in ac       Number of      resiliency
                                                                       (ha)          colonies          score
----------------------------------------------------------------------------------------------------------------
Archuleta.......................................................      11.9 (4.8)               1               1
Conejos.........................................................     39.2 (15.9)               1               3
Costilla........................................................       4.3 (1.7)               1               1
Garfield........................................................     25.8 (10.4)               1               2
La Plata........................................................       5.2 (2.1)               1               1
Mesa/Grand......................................................     45.6 (18.5)               6               9
Montrose/San Juan...............................................      19.9 (8.1)               2               5
Ouray...........................................................     38.6 (15.6)               2               5

[[Page 11763]]

 
San Miguel/Mora.................................................       1.5 (0.6)               2               3
Taos............................................................   522.2 (211.3)               4              11
----------------------------------------------------------------------------------------------------------------

    With 10 populations spread across 284 air miles (457 km) north to 
south and 237 air miles (381 km) east to west, there appears to be 
adequate redundancy should catastrophic events occur that cause 
extirpation of one or a few populations. However, if catastrophic 
events cause extirpation of the populations with the highest resiliency 
(Mesa/Grand, Montrose/San Juan, Ouray, and Taos), it could be quite 
detrimental to the viability of the subspecies because the six 
remaining populations have very low or low resiliency. Due to the low 
resiliency of many populations, more populations with sufficient 
resiliency would contribute to the subspecies' viability. Based on our 
evaluation of the 10 populations, we consider the current condition of 
the subspecies' redundancy to be moderate.
    The 10 silverspot populations represent the genetic and ecological 
variation (representation) currently known for this subspecies. Eight 
silverspot populations were identified based on genetic variation, 
which supports the ability of the subspecies to adapt over time to 
long-term changes in the environment (for example, climate change) 
(Cong et al. 2019, entire). However, 5 populations are comprised of a 
single colony, and all 10 populations appear isolated from one another. 
Genetic drift, the change in allele frequency in a population, is a 
particular concern for the small, isolated populations, and could 
impact the subspecies' adaptive capacity. In general, the bog violet 
and the silverspot occur in the same habitat across the range, but 
ecological representation adds to adaptive capacity because the 
silverspot occurs at different elevations and latitudes, such that 
overall, the silverspot has low to moderate representation. Future 
analysis of ecological settings at all colonies and populations is 
needed to improve our understanding of representation across the 
subspecies' range.
    In summary, there are currently 21 colonies representing the 10 
populations. In terms of resiliency, three populations are in very low 
condition, three in low condition, two in moderate condition, and two 
in high condition. Current redundancy is determined to be moderate, and 
representation is thought to be low to moderate.

Future Condition

    In the SSA report, we forecast the resiliency of silverspot 
populations and the redundancy and representation of the subspecies 
over the next approximately 30 years (to the year 2050) using a range 
of plausible future scenarios. This timeframe encompasses approximately 
30 generations of the subspecies, and we can reasonably rely on the 
climate model projections and our projections of the subspecies' 
response up to this point. Climate change impacts and human habitat 
impacts are likely to be the biggest drivers of changes to resiliency, 
redundancy, and representation for the silverspot. We evaluated four 
future scenarios that capture the range of plausible futures based on 
four climate models and future climate projections developed for 
southern Colorado and northern New Mexico (Rangwala 2020a, entire; 
2020b, entire). Three of the four models use representative 
concentration pathway (RCP; a greenhouse gas concentration trajectory) 
4.5, and the fourth uses RCP8.5. The RCP4.5 is considered a medium 
emissions trajectory, and the RCP8.5 is considered a high emissions 
trajectory. The higher the emissions, the greater chance the climate 
will change further from the 1971-2000 baseline. Current policies are 
projected to take us slightly above the RCP4.5 emission trends by mid-
century (Hausfather and Peters 2020, p. 260). The climate models are 
presented in the SSA report (Service 2023, tables 5-8, pp. 51-54).
    Using the four climate scenarios, we developed four future 
condition scenarios to evaluate the future viability of the silverspot. 
In simple terms, the four scenarios include:
    <bullet> Scenario 1: Warm Climate with Conservation Efforts;
    <bullet> Scenario 2: Hot and Dry Summers/Very Wet Winters with 
Conservation Efforts;
    <bullet> Scenario 3: Very Hot and Very Dry Summers/Wet Winters with 
No Conservation Efforts; and
    <bullet> Scenario 4: Hot and Very Dry Summers/Dry Winters with No 
Conservation Efforts.
    Because Scenarios 1 and 2 included potential future conservation 
efforts, which are not certain to occur and are not formalized in any 
conservation agreements, we did not consider these scenarios when 
determining if the silverspot meets the Act's definition of an 
endangered species or of a threatened species. However, Scenarios 1 and 
2 will inform our strategies for recovery of the subspecies. Therefore, 
our analysis in this final rule focuses on the future condition of the 
silverspot under Scenarios 3 and 4, as summarized below. Refer to the 
SSA report for full descriptions of the future scenarios (Service 2023, 
chapter 4, pp. 49-67).
Scenario 3
    Scenario 3 is characterized by the following assumptions:
    <bullet> An increase in direct habitat loss due to development 
occurs, particularly in colonies close to existing housing development.
    <bullet> Habitat fragmentation due to agricultural conversion 
remains unchanged from the current condition.
    <bullet> Greater negative effects from summer grazing occur because 
of dry or drought conditions (an increase from current condition) that 
reduce nectar sources.
    <bullet> No efforts are made to maintain current hydrology, and, in 
combination with dry or drought conditions, the habitat areas of small 
colonies will dry up and become extirpated and larger colonies are 
reduced in size (a decrease in suitable habitat from the current 
condition).
    <bullet> All populations receive a negative habitat factor score 
due to climate-related hydrologic alteration whether there is 
surrounding development or not.
    <bullet> No translocations of butterflies are implemented, and 
genetic diversity is low.
    <bullet> Climate emissions follow RCP8.5 (a high emissions 
scenario) with very hot and dry summers and wet winters.
Scenario 4
    Scenario 4 is characterized by the following assumptions:
    <bullet> We include the same assumptions as Scenario 3 for habitat 
loss and fragmentation, summer grazing,

[[Page 11764]]

hydrology and climate-related hydrologic factors, and translocation 
(the first six bullets, above).
    <bullet> Climate emissions follow RCP4.5 (a medium emissions 
scenario) with hot and very dry summers and dry winters.
Results of Scenarios 3 and 4
    Resiliency rankings for each population under Scenario 3 can be 
found in table 2, below, and in the SSA report (Service 2023, table 11, 
p. 64). Four of the previously ranked low or very low resiliency 
populations under current conditions are expected to become extirpated, 
three populations have a very low resiliency, two have low resiliency, 
and the Ouray population retains a moderate resiliency, surpassing the 
Mesa/Grand and Taos populations as the highest-ranking population. 
Extirpation of colonies will reduce resiliency and redundancy of 
populations and will also undoubtedly decrease representation relative 
to the current condition, causing a decline in subspecies' viability.
    Resiliency rankings for each population under Scenario 4 can be 
found in table 2, below, and in the SSA report (Service 2023, table 12, 
p. 66). As in Scenario 3, we expect climate change will cause the 
extirpation of four populations, which have habitat areas smaller than 
12 ac (5 ha). The size of habitat in the remaining populations is 
projected to decrease compared to the current condition. Compared to 
Scenario 3, habitat size is projected to be larger in the Colorado 
populations and smaller in the Taos population, but not enough to 
change the size scoring. With slightly less evaporative stress and 
slightly lower frequency of severe drought under Scenario 4 compared to 
Scenario 3, remaining populations may, in turn, be slightly more 
resilient in this scenario than in Scenario 3. However, using the 
resiliency scoring metrics in the SSA report, the minor differences in 
resiliency between the two scenarios are too small to result in 
different scores. Consequently, resiliency scorings are the same in 
both Scenarios 3 and 4, with four extirpated populations, three very 
low and two low resiliency populations, and only one moderately 
resilient population. Redundancy and representation are projected to be 
low, the same as in Scenario 3, and a decrease from the current 
condition.

Summary of Current and Future Conditions

    A comparison of the resiliency of each population for the current 
condition and future scenarios is presented below in table 2, and table 
3 presents a summary of redundancy and representation (see also Service 
2023, table 13, p. 67). Currently, we have determined that 3 of the 10 
silverspot populations are in a very low resiliency condition, 3 are in 
a low resiliency condition, 2 are in a moderate resiliency condition, 
and 2 of the largest populations are in a high resiliency condition. 
With 10 populations spread across the subspecies' range, there appears 
to be adequate redundancy should catastrophic events occur that cause 
the extirpation of one or a few populations, and we consider current 
redundancy to be moderate for the silverspot. It is likely there is 
sufficient representation and adaptability due to the genetic 
differences observed among populations. However, many of the 
populations are composed of a single colony, and all populations appear 
isolated genetically. In general, the bog violet and the silverspot 
occur in the same habitat across the subspecies' range, but ecological 
representation adds to adaptive capacity through occurrences at 
different elevations and latitudes and provides a low-to-moderate 
subspecies representation currently.
    The effects of future climate changes coupled with the continuation 
of other stressors that alter hydrology and cause habitat loss and 
fragmentation are projected to increase over the next 30 years in 
Scenarios 3 and 4, resulting in future conditions that cause 
resiliency, redundancy, and representation to decrease, and thus the 
subspecies' viability is expected to decrease from the current 
condition. Resiliency rankings are the same for Scenarios 3 and 4 with 
four extirpated populations, three very low and two low resiliency 
populations, and only one moderately resilient population. Redundancy 
and representation are both projected to be reduced from the current 
condition.

            Table 2--Summary of Silverspot Resiliency for Current Condition and Two Future Scenarios
----------------------------------------------------------------------------------------------------------------
                                                                                    Resiliency
                                                                 -----------------------------------------------
                           Population                                 Current         Future          Future
                                                                     condition      scenario 3      scenario 4
----------------------------------------------------------------------------------------------------------------
Archuleta.......................................................               1               0               0
Conejos.........................................................               3               2               2
Costilla........................................................               1               0               0
Garfield........................................................               2               1               1
La Plata........................................................               1               0               0
Mesa/Grand......................................................               9               1               1
Montrose/San Juan...............................................               5               1               1
Ouray...........................................................               5               5               5
San Miguel/Mora.................................................               3               0               0
Taos............................................................              11               3               3
----------------------------------------------------------------------------------------------------------------


   Table 3--Summary of Silverspot Redundancy and Representation for Current Condition and Two Future Scenarios
----------------------------------------------------------------------------------------------------------------
                                          Current condition        Future scenario 3        Future scenario 4
----------------------------------------------------------------------------------------------------------------
Redundancy...........................  Moderate...............  Very Low...............  Very Low.
Representation.......................  Low-Moderate...........  Low....................  Low.
----------------------------------------------------------------------------------------------------------------


[[Page 11765]]

Cumulative Effects
    We note that, by using the SSA framework to guide our analysis of 
the scientific information documented in the SSA report, we have 
analyzed the cumulative effects of identified threats and conservation 
actions on the subspecies. To assess the current and future condition 
of the subspecies, we evaluate the effects of all the relevant factors 
that may be influencing the subspecies, including threats and 
conservation efforts.
    Habitat loss and fragmentation, human-caused hydrologic alteration, 
livestock grazing, genetic isolation, exotic plant invasion, climate 
change, climate events, larval desiccation, and collecting are all 
factors that influence or could influence the subspecies' viability. 
These factors also have the potential to act cumulatively to impact 
silverspot viability and their cumulative impacts were considered in 
our characterization of the subspecies' current and future condition in 
the SSA report. Because the SSA framework considers not just the 
presence of the factors, but to what degree they collectively influence 
risk to the entire subspecies, our assessment integrates the cumulative 
effects of factors and replaces a standalone cumulative effects 
analysis.
Beneficial Factors
    Mowing or haying: Periodic mowing or haying, occasionally or once a 
year, appears to be beneficial to open the canopy for violets, to 
reduce a buildup of thatch from dead vegetation, and to keep woody 
vegetation from encroaching beyond what is suitable for the silverspot. 
Mowing or haying may approximate disturbance that would have occurred 
historically from native ungulate grazing or wildfire or both. Mowing 
in the early summer would allow for regrowth of vegetation and nectar 
plants suitable for the silverspot (Ellis 2020g, pers. comm.). Mowing 
once in the late summer or early fall could also potentially be 
compatible (Smith 2019, pers. comm.), but has a higher risk of reducing 
vegetation and nectar plants for that year's pupae and adults and 
possibly crushing pupae, eggs, and larvae. Occasional or annual mowing 
can, nonetheless, be beneficial to reduce competition from other plants 
if adequate nectar plants remain in the field or if there are enough 
within a short distance around the field to supply nectar to adult 
silverspots.
    Grazing: Winter and spring grazing (October to mid-April) can be 
beneficial to the silverspot (Arnold 1989, pp. 14-15). This is because 
removal of thatch from the dead vegetation limits competition in the 
spring for the violets. It also may approximate historical grazing 
patterns by native ungulates (deer and elk), which, in the winter, come 
down to lower valleys where there is less snow. Horses grazed an 
apparently healthy colony in the spring and summer (Arnold 1989, p. 
14), so some light to moderate grazing in the spring or summer appears 
to be acceptable. In contrast, grazing when violets have emerged and 
are actively growing (spring and summer) may be detrimental if 
livestock readily consume or trample the violets and possibly eggs, 
larvae, and pupae.
    Burning: Burning of meadows to reduce dead vegetation and reduce 
woody vegetation to suitable levels for the silverspot can also be 
beneficial and can possibly increase violet density (Arnold 1989, p. 
14; Ellis 1989, p. 14).
    Exotic plant invasion: Some exotic plants considered invasive or 
adventive may provide nectar sources that benefit the silverspot (Ellis 
1989, p. 14; Fisher 2020e, pers. comm.). However, especially with 
invasive plants, this may only be the case where native nectar plants 
have been substantially reduced or eliminated.
    Conservation efforts: The historical Unaweep Seep colony in the 
Mesa/Grand population was designated as a State Natural Area in 1983 
(Ellis 1999, p. 2). The Bureau of Land Management (BLM) also 
established a Research Natural Area around it in 1983 and designated it 
as an Area of Critical Environmental Concern (ACEC) through their 2015 
Resource Management Plan (Ellis 1989, p. 1; BLM 2015, pp. 207-208). 
Some monitoring, at least for the bog violet, occurred through 1999, 
but sometime after 1989 or possibly 1999, the colony became extirpated 
(Ellis 1999, entire). Habitat monitoring actions were recommended, but 
it is unclear whether any of them were ever implemented (Ellis 1999, 
pp. 8-9). Although the State of Colorado and the BLM implemented land 
conservation designations around the Unaweep Seep colony in the Mesa/
Grand population, this colony has been extirpated for at least 20 
years. Therefore, unless the bog violet and silverspot are translocated 
back to Unaweep Seep, the land designations do not benefit the 
silverspot. There are no other State regulatory mechanisms that benefit 
the silverspot in Colorado, New Mexico, or Utah. The Colorado State 
Wildlife Action Plan (SWAP) includes the silverspot, but there are no 
State statutes for management of the subspecies, so management would 
occur through cooperative efforts with other agencies or organizations.
    The BLM (Colorado), U.S. Forest Service (USFS) Region 2 (Colorado), 
and USFS Region 3 (New Mexico) have the silverspot on their sensitive 
species lists. The USFS Region 4 (Utah) does not, but no silverspots 
are currently known on USFS land in Utah. No silverspot colonies are 
currently known on USFS land in Colorado or New Mexico either, but the 
elevational range of the subspecies includes some lower elevation USFS 
land. The BLM does not have the silverspot on its sensitive species 
lists in either Utah or New Mexico. If species are on BLM sensitive 
species lists, the BLM works cooperatively with other Federal and State 
agencies and nongovernmental organizations to conserve these species 
and ensure that activities on BLM lands do not contribute to the need 
for their listing under the Act. Specific conservation objectives for 
BLM sensitive species are established in BLM land use plans. BLM's 
Grand Junction Field Office manages the Unaweep Seep property and, in 
addition to ACEC designation, includes management of the area for the 
butterfly in their 2015 Resource Management Plan (BLM 2015, pp. 207-
208, appendix B, appendix H). The butterfly is not included in other 
BLM land use plans in any of the other BLM resource areas in Colorado, 
New Mexico, or Utah, because the butterfly was not known to occur on 
BLM land in areas other than Unaweep Seep until very recently (only one 
new colony has been identified on BLM lands).
    Only three silverspot colonies are known to occur on public land 
(Federal and State lands), but there is potentially part of a fourth 
colony (unconfirmed) on public land in the Ouray population. 
Additionally, there are unsurveyed bog violet patches on State and 
Federal lands in the Garfield, Mesa/Grand, and Montrose/San Juan 
populations. Consequently, at present, any regulatory mechanisms or 
conservation efforts on State, BLM, and USFS lands, although 
contributing to conservation of the silverspot, would have a low impact 
on the silverspot's overall viability because most colonies and 
populations occur on private land.

Determination of Silverspot's Status

    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations (50 CFR part 424) set forth the procedures for determining 
whether a species meets the Act's definition of an endangered species 
or a threatened species. The Act defines an ``endangered species'' as a 
species in danger of extinction throughout all or a significant portion 
of

[[Page 11766]]

its range, and a ``threatened species'' as a species 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 a species meets the definition of endangered species or 
threatened species because of any of the following 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.

Status Throughout All of Its Range

    After evaluating threats to the species and assessing the 
cumulative effect of the threats under the Act's section 4(a)(1) 
factors, we found habitat loss and fragmentation (Factor A), 
incompatible livestock grazing (Factor A), human-caused hydrologic 
alteration (Factor A), and genetic isolation (Factor E) to be the main 
drivers of the silverspot's current condition, with the addition of the 
effects of climate change (Factor E) influencing future condition. 
These stressors all contribute to loss of habitat quantity and quality 
for the silverspot and for the bog violet, the plant on which 
silverspot larvae exclusively feed. These threats can currently occur 
anywhere in the range of the silverspot, and the future effects of 
climate change are expected to be ubiquitous throughout the subspecies' 
range. The existing regulatory mechanisms (Factor D) do not 
significantly affect the subspecies or ameliorate these stressors; 
thus, these stressors continue and are predicted to increase in 
prevalence in the future.
    Under the two future scenarios considered in this evaluation, we 
expect some populations to become extirpated and resiliency of the 
remaining populations to decrease. This would result in decreased 
redundancy and representation in the future compared to the current 
condition.
    We find that the silverspot is not currently in danger of 
extinction because the subspecies is still widespread with multiple 
populations of various sizes and levels of resiliency spread across its 
range, capturing known genetic and ecological variation. Therefore, the 
subspecies currently has sufficient redundancy and representation to 
withstand catastrophic events and maintain adaptability to changes. 
However, we expect that the stressors, individually and cumulatively, 
will reduce resiliency, redundancy, and representation within all parts 
of the range within the foreseeable future, in light of future climate 
change effects. Thus, after assessing the best available information, 
we conclude that the silverspot is not currently in danger of 
extinction but is likely to become in danger of extinction within the 
foreseeable future throughout all of its range. This finding is based 
on anticipated reductions in resiliency, redundancy, and representation 
in the future as a result of predicted loss and degradation of wet 
meadow habitat from the synergistic and cumulative interactions between 
climate change and other stressors. Climate change is predicted to 
increase temperatures and decrease water availability and snowpack 
necessary to maintain the wet meadows that the silverspot and bog 
violet need. This, coupled with the continuation of other stressors 
that alter hydrology and cause habitat loss and fragmentation, is 
expected to impact the future viability of this subspecies. We can 
reasonably determine that both the future threats and the subspecies' 
responses to those threats are likely within a 30-year timeframe (i.e., 
the foreseeable future). Thus, after assessing the best available 
information, we determine that the silverspot is not currently in 
danger of extinction but is likely to become in danger of extinction 
within the foreseeable future throughout all of its range.

Status Throughout a Significant Portion of Its Range

    Under the Act and our implementing regulations, a species may 
warrant listing if it is in danger of extinction or likely to become so 
in the foreseeable future throughout all or a significant portion of 
its range. The court in Center for Biological Diversity v. Everson, 435 
F. Supp. 3d 69 (D.D.C. 2020) (Everson), vacated the provision of the 
Final Policy on Interpretation of the Phrase ``Significant Portion of 
Its Range'' in the Endangered Species Act's Definitions of ``Endangered 
Species'' and ``Threatened Species'' (Final Policy; 79 FR 37578, July 
1, 2014) that provided if the Services determine that a species is 
threatened throughout all of its range, the Services will not analyze 
whether the species is endangered in a significant portion of its 
range.
    Therefore, we proceed to evaluating whether the species is 
endangered in a significant portion of its range--that is, whether 
there is any portion of the species' range for which both (1) the 
portion is significant; and (2) the species is in danger of extinction 
in that portion. Depending on the case, it might be more efficient for 
us to address the ``significance'' question or the ``status'' question 
first. We can choose to address either question first. Regardless of 
which question we address first, if we reach a negative answer with 
respect to the first question that we address, we do not need to 
evaluate the other question for that portion of the species' range.
    Following the court's holding in Everson, we now consider whether 
there are any significant portions of the species' range where the 
species is in danger of extinction now (i.e., endangered). In 
undertaking this analysis for the silverspot, we choose to address the 
status question first--we consider information pertaining to the 
geographic distribution of both the subspecies and the threats that the 
subspecies faces to identify portions of the range where the subspecies 
may be endangered.
    We evaluated the range of the silverspot to determine if the 
species is in danger of extinction now in any portion of its range. The 
range of a species can theoretically be divided into portions in an 
infinite number of ways. We focused our analysis on portions of the 
subspecies' range that may meet the definition of an endangered 
species.
    For the silverspot, we considered whether the threats or their 
effects on the subspecies are greater in any biologically meaningful 
portion of the subspecies' range than in other portions such that the 
subspecies is in danger of extinction now in that portion. We examined 
the following threats: Habitat loss and fragmentation; livestock 
grazing; human-caused hydrologic alteration; genetic isolation; climate 
change; climate events; invasion by nonnative plants; larval 
desiccation; and collecting. These are all factors that influence or 
could influence the subspecies' viability, including cumulative 
effects. All of these threats are similar in scope, scale, and 
distribution across the range of the subspecies. The spatial 
distribution of these threats is evenly distributed throughout the 
range and not concentrated in any particular area. However, there are 
several smaller populations distributed throughout the range that are 
currently in low resiliency condition and therefore could experience an 
elevated risk of extinction in the future (see tables 1 and 2, above). 
These smaller populations are not concentrated in their location, 
instead they are distributed across the range with more highly 
resilient populations interspersed between them. These smaller 
populations are not at risk of extinction currently due to the lack of 
imminent threats, as described in our

[[Page 11767]]

analysis above. Climate events are currently a minor factor and when 
considered with the other stressors are not expected to reduce the 
subspecies' viability in the near term. The risk of extinction of the 
smaller populations increases in the foreseeable future when climate 
change becomes a major factor and when other major factors such as 
habitat loss and degradation are predicted to increase. Therefore, the 
smaller populations risk of extinction is influenced by the predicted 
increase in threats from habitat loss and degradation, climate change, 
and (to a lesser extent) the other stressors analyzed in this rule, and 
their future effects to the silverspot.
    We found no portion of the silverspot's range where threats are 
impacting individuals differently from how they are affecting the 
subspecies elsewhere in its range, or where the biological condition of 
the subspecies differs from its condition elsewhere in its range such 
that the status of the subspecies in that portion differs from any 
other portion of the subspecies' range. Therefore, no portion of the 
subspecies' range provides a basis for determining that the subspecies 
is in danger of extinction in a significant portion of its range, and 
we determine that the subspecies is likely to become in danger of 
extinction within the foreseeable future throughout all of its range. 
This does not conflict with the courts' holdings in Desert Survivors v. 
U.S. Department of the Interior, 321 F. Supp. 3d 1011, 1070-74 (N.D. 
Cal. 2018), and Center for Biological Diversity v. Jewell, 248 F. Supp. 
3d 946, 959 (D. Ariz. 2017), because, in reaching this conclusion, we 
did not apply the aspects of the Final Policy, including the definition 
of ``significant'' that those court decisions held to be invalid.

Determination of Status

    Our review of the best scientific and commercial data available 
indicates that the silverspot meets the Act's definition of a 
threatened species. Therefore, we are listing the silverspot as a 
threatened species in accordance with sections 3(20) and 4(a)(1) of the 
Act.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened species under the Act include recognition as a listed 
species, planning and implementation of recovery actions, requirements 
for Federal protection, and prohibitions against certain practices. 
Recognition through listing results in public awareness, and 
conservation by Federal, State, Tribal, and local agencies, private 
organizations, and individuals. The Act encourages cooperation with the 
States and other countries and calls for recovery actions to be carried 
out for listed species. The protection required by Federal agencies, 
including the Service, and the prohibitions against certain activities 
are discussed, in part, below.
    The primary purpose of the Act is the conservation of endangered 
and threatened species and the ecosystems upon which they depend. The 
ultimate goal of such conservation efforts is the recovery of these 
listed species, so that they no longer need the protective measures of 
the Act. Section 4(f) of the Act calls for the Service to develop and 
implement recovery plans for the conservation of endangered and 
threatened species. The goal of this process is to restore listed 
species to a point where they are secure, self-sustaining, and 
functioning components of their ecosystems.
    Recovery planning consists of preparing draft and final recovery 
plans, beginning with the development of a recovery outline and making 
it available to the public soon after a final listing determination. 
The recovery outline guides the immediate implementation of urgent 
recovery actions and describes the process to be used to develop a 
recovery plan. The recovery planning process involves the 
identification of actions that are necessary to halt and reverse the 
species' decline by addressing the threats to its survival and 
recovery. The recovery plan also identifies recovery criteria for 
review of when a species may be ready for reclassification from 
endangered to threatened (``downlisting'') or removal from protected 
status (``delisting''), and methods for monitoring recovery progress. 
Recovery plans also establish a framework for agencies to coordinate 
their recovery efforts and provide estimates of the cost of 
implementing recovery tasks. Recovery teams (composed of species 
experts, Federal and State agencies, nongovernmental organizations, and 
stakeholders) may be established to develop recovery plans. Revisions 
of the plan may be done to address continuing or new threats to the 
species, as new substantive information becomes available. When 
completed, the recovery outline, draft recovery plan, and the final 
recovery plan will be available on our website (https://www.fws.gov/program/endangered-species), or from our Colorado Ecological Services 
Field Office (see FOR FURTHER INFORMATION CONTACT).
    Implementation of recovery actions generally requires the 
participation of a broad range of partners, including other Federal 
agencies, States, Tribes, nongovernmental organizations, businesses, 
and private landowners. Examples of recovery actions include habitat 
restoration (e.g., restoration of native vegetation), research, captive 
propagation and reintroduction, and outreach and education. The 
recovery of many listed species cannot be accomplished solely on 
Federal lands because their range may occur primarily or solely on non-
Federal lands. For many listed species, achieving recovery requires 
cooperative conservation efforts on private, State, and Tribal lands.
    Once this subspecies is listed (see DATES above), funding for 
recovery actions will be available from a variety of sources, including 
Federal budgets, State programs, and cost-share grants for non-Federal 
landowners, the academic community, and nongovernmental organizations. 
In addition, pursuant to section 6 of the Act, the States of Colorado, 
New Mexico, and Utah will be eligible for Federal funds to implement 
management actions that promote the protection or recovery of the 
silverspot. Information on our grant programs that are available to aid 
the subspecies recovery can be found at: https://www.fws.gov/service/financial-assistance.
    Please let us know if you are interested in participating in 
recovery efforts for the silverspot. Additionally, we invite you to 
submit any new information on this subspecies whenever it becomes 
available and any information you may have for recovery planning 
purposes (see FOR FURTHER INFORMATION CONTACT).
    Section 7 of the Act is titled Interagency Cooperation and mandates 
all Federal action agencies to use their existing authorities to 
further the conservation purposes of the Act and to ensure that their 
actions are not likely to jeopardize the continued existence of listed 
species or adversely modify critical habitat. Regulations implementing 
section 7 are codified at 50 CFR part 402.
    Section 7(a)(2) states that each Federal action agency shall, in 
consultation with the Secretary, ensure that any action they authorize, 
fund, or carry out is not likely to jeopardize the continued existence 
of a listed species or result in the destruction or adverse 
modification of designated critical habitat. Each Federal agency shall 
review its action at the earliest possible time to determine whether it 
may affect listed species or critical habitat. If a determination is 
made that the action may affect listed species or critical habitat, 
formal consultation is required (50 CFR 402.14(a)), unless the Service 
concurs in

[[Page 11768]]

writing that the action is not likely to adversely affect listed 
species or critical habitat. At the end of a formal consultation, the 
Service issues a biological opinion, containing its determination of 
whether the federal action is likely to result in jeopardy or adverse 
modification.
    Examples of discretionary actions for the silverspot that may be 
subject to consultation procedures under section 7 are land management 
or other landscape-altering activities on Federal lands administered by 
the U.S. Fish and Wildlife Service, Bureau of Land Management, Bureau 
of Indian Affairs, Bureau of Reclamation, National Park Service, and 
U.S. Forest Service as well as actions on State, Tribal, local, or 
private lands that require a Federal permit (such as a permit from the 
U.S. Army Corps of Engineers under section 404 of the Clean Water Act 
(33 U.S.C. 1251 et seq.) or a permit from the Service under section 10 
of the Act) or that involve some other Federal action (such as funding 
from the Federal Highway Administration, Federal Aviation 
Administration, or the Federal Emergency Management Agency). Federal 
actions not affecting listed species or critical habitat--and actions 
on State, Tribal, local, or private lands that are not federally 
funded, authorized, or carried out by a Federal agency--do not require 
section 7 consultation. Federal agencies should coordinate with the 
local Service Field Office (see FOR FURTHER INFORMATION CONTACT) with 
any specific questions on Section 7 consultation and conference 
requirements.
    It is the policy of the Services, as published in the Federal 
Register on July 1, 1994 (59 FR 34272), to identify to the extent known 
at the time a species is listed, specific activities that will not be 
considered likely to result in violation of section 9 of the Act. To 
the extent possible, activities that will be considered likely to 
result in violation will also be identified in as specific a manner as 
possible. The intent of this policy is to increase public awareness of 
the effect of a listing on proposed and ongoing activities within the 
range of the species. Although most of the prohibitions in section 9 of 
the Act apply to endangered species, sections 9(a)(1)(G) and 9(a)(2)(E) 
of the Act prohibit the violation of any regulation under section 4(d) 
pertaining to any threatened species of fish or wildlife, or threatened 
species of plant, respectively. Section 4(d) of the Act directs the 
Secretary to promulgate protective regulations that are necessary and 
advisable for the conservation of threatened species. As a result, we 
interpret our policy to mean that, when we list a species as a 
threatened species, to the extent possible, we identify activities that 
will or will not be considered likely to result in violation of the 
protective regulations under section 4(d) for that species.
    At this time, we are unable to identify specific activities that 
will or will not be considered likely to result in violation of section 
9 of the Act beyond what is already clear from the descriptions of 
prohibitions and exceptions established by protective regulation under 
section 4(d) of the Act.
    Questions regarding whether specific activities would constitute 
violation of section 9 of the Act should be directed to the Colorado 
Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT).

II. Final Rule Issued Under Section 4(d) of the Act

Background

    Section 4(d) of the Act contains two sentences. The first sentence 
states that the Secretary shall issue such regulations as she deems 
necessary and advisable to provide for the conservation of species 
listed as threatened. The U.S. Supreme Court has noted that statutory 
language similar to the language in section 4(d) of the Act authorizing 
the Secretary to take action that she ``deems necessary and advisable'' 
affords a large degree of deference to the agency (see Webster v. Doe, 
486 U.S. 592, 600 (1988)). Conservation is defined in the Act to mean 
the use of all methods and procedures which are necessary to bring any 
endangered species or threatened species to the point at which the 
measures provided pursuant to the Act are no longer necessary. 
Additionally, the second sentence of section 4(d) of the Act states 
that the Secretary may by regulation prohibit with respect to any 
threatened species any act prohibited under section 9(a)(1), in the 
case of fish or wildlife, or section 9(a)(2), in the case of plants. 
Thus, the combination of the two sentences of section 4(d) provides the 
Secretary with wide latitude of discretion to select and promulgate 
appropriate regulations tailored to the specific conservation needs of 
the threatened species. The second sentence grants particularly broad 
discretion to the Service when adopting the prohibitions under section 
9.
    The courts have recognized the extent of the Secretary's discretion 
under this standard to develop rules that are appropriate for the 
conservation of a species. For example, courts have upheld rules 
developed under section 4(d) as a valid exercise of agency authority 
where they prohibited take of threatened wildlife or include a limited 
taking prohibition (see Alsea Valley Alliance v. Lautenbacher, 2007 
U.S. Dist. Lexis 60203 (D. Or. 2007); Washington Environmental Council 
v. National Marine Fisheries Service, 2002 U.S. Dist. Lexis 5432 (W.D. 
Wash. 2002)). Courts have also upheld 4(d) rules that do not address 
all of the threats a species faces (see State of Louisiana v. Verity, 
853 F.2d 322 (5th Cir. 1988)). As noted in the legislative history when 
the Act was initially enacted, ``once an animal is on the threatened 
list, the Secretary has an almost infinite number of options available 
to [her] with regard to the permitted activities for those species. 
[She] may, for example, permit taking, but not importation of such 
species, or [she] may choose to forbid both taking and importation but 
allow the transportation of such species'' (H.R. Rep. No. 412, 93rd 
Cong., 1st Sess. 1973).
    The provisions of this 4(d) rule will promote conservation of the 
silverspot by encouraging management of the landscape in ways that meet 
both land management considerations and the conservation needs of the 
silverspot. The provisions of this rule are one of many tools that we 
will use to promote the conservation of the silverspot.
    As mentioned previously in ``Available Conservation Measures,'' 
section 7(a)(2) of the Act requires Federal agencies, including the 
Service, to ensure that any action they fund, authorize, or carry out 
is not likely to jeopardize the continued existence of any endangered 
species or threatened species or result in the destruction or adverse 
modification of designated critical habitat of such species.
    These requirements are the same for a threatened species with a 
species-specific 4(d) rule. For example, as with an endangered species, 
if a Federal agency determines that an action is ``not likely to 
adversely affect'' a threatened species will require the Service's 
written concurrence (50 CFR 402.13(c). Similarly, if a Federal agency 
determines that an action is ``likely to adversely affect'' a 
threatened species, the action will require formal consultation and the 
formulation of a biological opinion (50 CFR 402.14(a)).

Provisions of the 4(d) Rule

    Exercising the Secretary's authority under section 4(d), we have 
developed a rule that is designed to address the silverspot's specific 
threats and conservation needs. As discussed above under ``Summary of 
Biological Status

[[Page 11769]]

and Threats,'' we have concluded that the silverspot is likely to 
become in danger of extinction within the foreseeable future primarily 
due to the individual and cumulative effects of habitat loss and 
fragmentation, incompatible livestock grazing, human-caused hydrologic 
alteration, genetic isolation, and climate change. Section 4(d) 
requires the Secretary to issue such regulations as she deems necessary 
and advisable to provide for the conservation of each threatened 
species and authorizes the Secretary to include among those protective 
regulations any of the prohibitions that section 9(a)(1) of the Act 
prescribes for endangered species. We find that the protections, 
prohibitions, and exceptions in this rule as a whole satisfy the 
requirement in section 4(d) of the Act to issue regulations deemed 
necessary and advisable to provide for the conservation of the 
silverspot.
    The protective regulations for the silverspot incorporate 
prohibitions from section 9(a)(1) to address the threats to the 
species. Section 9(a)(1) prohibits the following activities for 
endangered wildlife: importing or exporting; take; possession and other 
acts with unlawfully taken specimens; delivering, receiving, carrying, 
transporting, or shipping in interstate or foreign commerce in the 
course of commercial activity; or selling or offering for sale in 
interstate or foreign commerce. This protective regulation includes all 
of these prohibitions because the silverspot is at risk of extinction 
in the foreseeable future and putting these prohibitions in place will 
help to preserve the subspecies' remaining populations, slow their rate 
of decline, and decrease synergistic, negative effects from other 
threats.
    This 4(d) rule will provide for the conservation of the silverspot 
by prohibiting the following activities, except as otherwise authorized 
or permitted (e.g., allowed for in an exception or authorized by a 
permit issued under section 10(a)(1)(A) of the Act): importing or 
exporting; possession and other acts with unlawfully taken specimens; 
delivering, receiving, carrying, transporting, or shipping in 
interstate or foreign commerce in the course of commercial activity; or 
selling or offering for sale in interstate or foreign commerce. In 
addition, anyone taking, attempting to take, or otherwise possessing a 
silverspot, or parts thereof, in violation of section 9 of the Act will 
be subject to a penalty under section 11 of the Act, with certain 
exceptions (discussed below).
    Under the Act, ``take'' means to harass, harm, pursue, hunt, shoot, 
wound, kill, trap, capture, or collect, or to attempt to engage in any 
such conduct. Some of these provisions have been further defined in 
regulation at 50 CFR 17.3. Take can result knowingly or otherwise, by 
direct and indirect impacts, intentionally or incidentally. Regulating 
incidental and intentional take will help preserve the subspecies' 
remaining populations, slow their rate of decline, and decrease 
synergistic, negative effects from other threats.
    Exceptions to the prohibition on take include all of the general 
exceptions to the prohibition on take of endangered wildlife, as set 
forth in 50 CFR 17.21 and additional exceptions, as described below.
    The 4(d) rule will also provide for the conservation of the species 
by allowing exceptions that incentivize conservation actions or that, 
while they may have some minimal level of take of the silverspot, are 
not expected to rise to the level that would have a negative impact 
(i.e., would have only de minimis impacts) on the subspecies' 
conservation.
    As discussed above under ``Summary of Biological Status and 
Threats'', livestock grazing, exotic plant invasion, prescribed 
burning, and use of pesticides affect the status of the silverspot both 
negatively and positively depending on how, when, and where they are 
done. Accordingly, this final 4(d) rule addresses activities to 
facilitate conservation and management of the silverspot where the 
subspecies currently occurs and may occur in the future by excepting 
the activities from the Act's take prohibition under certain specific 
conditions. These activities are intended to increase management 
flexibility and encourage support for the conservation and habitat 
improvement of the silverspot. Under this 4(d) rule, take will be 
prohibited, except for take incidental to an otherwise lawful activity 
described in the exceptions to prohibitions in the 4(d) rule for the 
purpose of silverspot conservation or recovery.
    The specific exceptions to the prohibitions for specific types of 
incidental take under this 4(d) rule are explained in more detail 
below. For all of these, reasonable care must be practiced to minimize 
the impacts from the actions. Reasonable care means limiting the 
impacts to the silverspot and its host plant (bog violet) by complying 
with any and all applicable Federal, State, and Tribal regulations for 
the activity in question; using methods and techniques that result in 
the least harm, injury, or death, as feasible; undertaking activities 
at the least impactful times (e.g., conducting activities that might 
impact habitat during the flight season) and locations, as feasible; 
ensuring the number of individuals affected does not impact the 
existing populations; minimizing the potential to introduce invasive 
plant species; and preserving the genetic diversity of populations.
    Under this 4(d) rule, incidental take of a silverspot will not be a 
violation of section 9 of the Act if it occurs as a result of the 
following activities. All activities and statements below only apply in 
habitat areas of silverspot that include wet meadow areas where bog 
violets are growing and immediately adjacent areas with nectar plants.

Livestock Grazing

    By excepting take of the silverspot caused by grazing, we 
acknowledge the positive role that some ranchers have already played in 
conserving the silverspot and the importance of preventing any 
additional loss and fragmentation of native grasslands and riparian 
habitat. Grazing (and browsing) by livestock may improve silverspot 
habitat by opening up tree or shrub canopy cover in the habitat and 
removing herbaceous vegetation that shades and competes with the bog 
violet, thereby reducing its abundance. Grazing may be an effective 
tool to improve silverspot habitat when carefully applied in 
cooperation and consultation with private landowners, public land 
managers, and grazing experts. Moderate vegetative utilization (40-55 
percent) in late fall to early spring (October 15 to May 31) is 
excepted under this 4(d) rule. Resting pastures that include silverspot 
habitat is preferred in summer through fall (June 1 to October 14), but 
light grazing (less than 30 percent utilization) during this timeframe 
is also excepted from take because it may reduce competition for the 
bog violet. Recovery of the silverspot will depend on the protection 
and restoration of high-quality habitats supporting the bog violet on 
private lands and on public lands that are grazed by private 
individuals under lease or other agreements.

Annual Haying or Mowing

    Annual haying or mowing in early summer can be beneficial, or at 
least not detrimental, to the silverspot by removing vegetation that 
competes with the bog violet for light, nutrients, and water and 
reduces the violet's abundance. Therefore, we except take from annual 
haying or mowing in silverspot habitat under the following conditions: 
activities must occur in the early summer (June 30 or earlier), and 
blade height must be a minimum of 6

[[Page 11770]]

inches above the ground, with 8 inches or higher preferred in areas 
with bog violet to avoid cutting the violet leaves. The timing of 
cutting also applies to adjacent drier habitat areas that contain 
nectar plants, an important food source for adult butterflies, but 
blade height may be lower than 6 inches where the bog violet is not 
present. However, haying or mowing from July 1 through October would be 
detrimental due to removal of nectar plants and cover for all 
silverspot life stages, and therefore is not excepted from the 
prohibitions in this 4(d) rule in and adjacent to bog violet habitat.

Prescribed Burning

    Spring burning can be beneficial to remove thatch that may reduce 
or prevent growth of the bog violet. Prescribed burning in the spring 
(March 1 to April 30) has limited impact to silverspots and is excepted 
from take. Fall burning (October 15 to December 15) is also excepted if 
adequate monitoring (i.e., at least two surveys at times when 
butterflies are active) is performed on the property during the adult 
flight period of that year and does not detect the silverspot.

Brush Control

    Some woody vegetation interspersed in silverspot habitat or at the 
margins of habitat can be beneficial for bog violet survival and growth 
by providing some protection from livestock grazing and trampling and a 
future substrate for violet establishment on old decaying logs (Ireland 
2021a, pers. comm.). However, if allowed to become too dense, woody 
vegetation can crowd out bog violets and nectar plants. Consequently, 
brush removal every 4 to 5 years is excepted from take and may occur at 
any time during the year. Removal can be by mechanical means, burning, 
grazing, or herbicide application if in compliance with other excepted 
activities in the 4(d) rule. If mechanical means such as a brush hog is 
used, the blade must be set to 8 inches or higher above the ground. If 
herbicides are used, an appropriate systemic herbicide to prevent 
regrowth must be directly applied to cut stems. Broadcast spraying in 
silverspot habitat is prohibited because it may remove all nectar 
plants for the butterfly.

Noxious Weed Control

    Although some noxious weeds like Canada thistle provide nectar 
sources for silverspot, spot spraying, hand pulling, or mechanical 
treatment of noxious weeds is excepted from take and may occur at any 
time during the year. High densities of noxious weeds can be 
detrimental to the bog violet and their control can benefit the 
silverspot. However, broadcast spraying in silverspot habitat is 
prohibited because it may remove all nectar plants for the butterfly.

Fence Maintenance

    Excepted activities related to fence maintenance include 
replacement of poles and wire, and aboveground removal of woody 
vegetation along fence lines. These activities may occur at any time 
during the year. Fences help manage where cattle and other livestock 
can graze and reduce unwanted impacts to bog violet habitat. Removal of 
woody vegetation can prevent encroachment of vegetation into bog violet 
habitat and reduces competition with bog violet. If removal of woody 
vegetation is done by machine, such as a brush hog, the machine blade 
must be set 8 inches or higher above ground to avoid or minimize damage 
to the bog violet. If permanent removal of woody vegetation is desired, 
we recommend a systemic herbicide be directly applied to the cut stems 
of woody vegetation. However, as stated earlier, broadcast spraying in 
silverspot habitat is prohibited because it may remove all nectar 
plants for the butterfly.

Maintenance and Operation of Existing Utility Corridors

    Maintenance and operation of existing utility infrastructure within 
and immediately adjacent to silverspot habitat are excepted from take 
within existing rights-of-way for standard activities to repair and 
maintain existing transmission towers, lines, access roads, and to 
perform brush control. These activities are excepted from take year-
round and as needed with no restriction on frequency. Replacement of 
existing structures and the installation of new structures and 
infrastructure such as access roads are not excepted. Noxious weed 
control and fence maintenance must abide by the exceptions for these 
activities identified in the 4(d) rule.

Maintenance of Other Structures

    Maintenance of other existing structures within and immediately 
adjacent to silverspot habitat is excepted if activities are kept 
within the confines of already disturbed ground so as to not disturb 
the subspecies or its habitat.
    Despite these prohibitions regarding threatened species, we may 
under certain circumstances issue permits to carry out one or more 
otherwise prohibited activities, including those described above. The 
regulations that govern permits for threatened wildlife state that the 
Director may issue a permit authorizing any activity otherwise 
prohibited with regard to threatened species. These include permits 
issued for the following purposes: for scientific purposes, to enhance 
propagation or survival, for economic hardship, for zoological 
exhibition, for educational purposes, for incidental taking, or for 
special purposes consistent with the purposes of the Act (50 CFR 
17.32). The statute also contains certain exemptions from the 
prohibitions, which are found in sections 9 and 10 of the Act.
    We recognize the special and unique relationship with our State 
natural resource agency partners in contributing to conservation of 
listed species. State agencies often possess scientific data and 
valuable expertise on the status and distribution of endangered, 
threatened, and candidate species of wildlife and plants. State 
agencies, because of their authorities and their close working 
relationships with local governments and landowners, are in a unique 
position to assist us in implementing all aspects of the Act. In this 
regard, section 6 of the Act provides that we must cooperate to the 
maximum extent practicable with the States in carrying out programs 
authorized by the Act. Therefore, any qualified employee or agent of a 
State conservation agency that is a party to a cooperative agreement 
with us in accordance with section 6(c) of the Act, who is designated 
by his or her agency for such purposes, will be able to conduct 
activities designed to conserve the silverspot that may result in 
otherwise prohibited take without additional authorization.
    Nothing in this 4(d) rule will change in any way the recovery 
planning provisions of section 4(f) of the Act, the consultation 
requirements under section 7 of the Act, or the ability of the Service 
to enter into partnerships for the management and protection of the 
silverspot. However, interagency cooperation may be further streamlined 
through planned programmatic consultations for the subspecies between 
Federal agencies and the Service.

III. Critical Habitat

    Section 4(a)(3) of the Act, as amended, and implementing 
regulations (50 CFR 424.12), require that, to the maximum extent 
prudent and determinable, the Secretary shall designate critical 
habitat at the time the species is determined to be an endangered or 
threatened species. Our regulations (50 CFR 424.12(a)(1)) state that 
the Secretary may, but is not required to, determine that a

[[Page 11771]]

designation would not be prudent in the following circumstances:
    <bullet> The species is threatened by taking or other human 
activity and identification of critical habitat can be expected to 
increase the degree of such threat to the species;
    <bullet> The present or threatened destruction, modification, or 
curtailment of a species' habitat or range is not a threat to the 
species, or threats to the species' habitat stem solely from causes 
that cannot be addressed through management actions resulting from 
consultations under section 7(a)(2) of the Act;
    <bullet> Areas within the jurisdiction of the United States provide 
no more than negligible conservation value, if any, for a species 
occurring primarily outside the jurisdiction of the United States;
    <bullet> No areas meet the definition of critical habitat; or
    <bullet> The Secretary otherwise determines that designation of 
critical habitat would not be prudent based on the best scientific data 
available.
    In this final rule, we affirm the prudency determination we made in 
our May 4, 2022, proposed rule (87 FR 26319 at pp. 26335-26336) 
concerning the designation of critical habitat for the silverspot. We 
find that the designation of critical habitat is not prudent for the 
silverspot, 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 these 
threats to the subspecies. Designation of critical habitat requires the 
publication of maps and a narrative description of specific critical 
habitat areas in the Federal Register. The degree of detail in those 
maps and boundary descriptions is greater than the general location 
descriptions provided in this final rule. We find that the publication 
of maps and descriptions outlining the locations of the silverspot 
would likely facilitate unauthorized collection and trade, as 
collectors would know the exact locations where silverspots occur. The 
silverspot has been collected in the past, and there is potential for 
collection pressure to increase if specific locations of populations 
were to become widely known (Ellis 2020f, pers. comm.). Butterflies in 
general are highly sought after by collectors in the illegal animal 
trade (Courchamp et al. 2006, entire). We are concerned that the 
publicity from listing the silverspot may result in greater interest 
from collectors and make the subspecies more desirable for collection 
because of its rarity as has been documented for other rare butterflies 
(Hoekwater 1997, entire; Courchamp et al. 2006, entire; O'Neill 2007, 
entire; Stratton 2012, entire; Lewis 2018, entire). Therefore, a 
designation of critical habitat would be detrimental for the 
subspecies. For more information on the rationale for our determination 
that designation of critical habitat is not prudent, see the May 4, 
2022, proposed rule (87 FR 26319 at pp. 26335-26336).

Required Determinations

National Environmental Policy Act (42 U.S.C. 4321 et seq.)

    Regulations adopted pursuant to section 4(a) of the Act are exempt 
from the National Environmental Policy Act (NEPA; 42 U.S.C. 4321 et 
seq.) and do not require an environmental analysis under NEPA. We 
published a notice outlining our reasons for this determination in the 
Federal Register on October 25, 1983 (48 FR 49244). This includes 
listing, delisting, and reclassification rules, as well as critical 
habitat designations and species-specific protective regulations 
promulgated concurrently with a decision to list or reclassify a 
species as threatened. The courts have upheld this position (e.g., 
Douglas County v. Babbitt, 48 F.3d 1495 (9th Cir. 1995) (critical 
habitat); Center for Biological Diversity v. U.S. Fish and Wildlife 
Service., 2005 WL 2000928 (N.D. Cal. Aug. 19, 2005) (concurrent 4(d) 
rule)).

Government-to-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994 
(Government-to-Government Relations with Native American Tribal 
Governments; 59 FR 22951), Executive Order 13175 (Consultation and 
Coordination with Indian Tribal Governments), and the Department of the 
Interior's manual at 512 DM 2, we readily acknowledge our 
responsibility to communicate meaningfully with federally recognized 
Tribes on a government-to-government basis. In accordance with 
Secretary's Order 3206 of June 5, 1997 (American Indian Tribal Rights, 
Federal-Tribal Trust Responsibilities, and the Endangered Species Act), 
we readily acknowledge our responsibilities to work directly with 
Tribes in developing programs for healthy ecosystems, to acknowledge 
that Tribal lands are not subject to the same controls as Federal 
public lands, to remain sensitive to Indian culture, and to make 
information available to Tribes. Thirty-eight Tribes with cultural 
claims or affiliation to land or with lands currently in the range of 
the silverspot were contacted via letter to solicit input on the SSA 
report. One Tribe responded and stated that they do not have scientific 
data but would like to be kept informed of the SSA findings. We 
notified Tribes of the May 4, 2022, proposed listing determination and 
this final determination.

References Cited

    A complete list of references cited in this rulemaking is available 
on the internet at https://www.regulations.gov and upon request from 
the Colorado Ecological Services Field Office (see FOR FURTHER 
INFORMATION CONTACT).

Authors

    The primary authors of this final rule are the staff members of the 
Fish and Wildlife Service's Species Assessment Team and the Colorado 
Ecological Services Field Office.

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Plants, 
Reporting and recordkeeping requirements, Transportation, Wildlife.

Regulation Promulgation

    Accordingly, we amend part 17, subchapter B of chapter I, title 50 
of the Code of Federal Regulations, as set forth below:

PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS

0
1. The authority citation for part 17 continues to read as follows:

    Authority:  16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, 
unless otherwise noted.


0
2. In Sec.  17.11, in paragraph (h), amend the List of Endangered and 
Threatened Wildlife by adding an entry for ``Butterfly, silverspot'' in 
alphabetical order under INSECTS to read as follows:


Sec.  17.11   Endangered and threatened wildlife.

* * * * *
    (h) * * *

[[Page 11772]]



----------------------------------------------------------------------------------------------------------------
                                                                                          Listing citations and
           Common name              Scientific name      Where listed         Status         applicable rules
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
             Insects
 
                                                  * * * * * * *
Butterfly, silverspot...........  Speyeria nokomis    Wherever found....  T              89 FR [INSERT FEDERAL
                                   nokomis.                                               REGISTER PAGE WHERE
                                                                                          THE DOCUMENT BEGINS],
                                                                                          February 15, 2024; 50
                                                                                          CFR 17.47(h).\4d\
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------


0
3. Amend Sec.  17.47 by adding paragraph (h) to read as follows:


Sec.  17.47   Special rules--insects.

* * * * *
    (h) Silverspot butterfly (Speyeria nokomis nokomis). (1) 
Prohibitions. The following prohibitions that apply to endangered 
wildlife also apply to the silverspot butterfly. Except as provided 
under paragraphs (h)(2) and (3) of this section and Sec. Sec.  17.4 and 
17.5, it is unlawful for any person subject to the jurisdiction of the 
United States to commit, to attempt to commit, to solicit another to 
commit, or cause to be committed, any of the following acts in regard 
to this species:
    (i) Import or export, as set forth at Sec.  17.21(b) for endangered 
wildlife.
    (ii) Take, as set forth at Sec.  17.21(c)(1) for endangered 
wildlife.
    (iii) Possession and other acts with unlawfully taken specimens, as 
set forth at Sec.  17.21(d)(1) for endangered wildlife.
    (iv) Interstate or foreign commerce in the course of commercial 
activity, as set forth at Sec.  17.21(e) for endangered wildlife.
    (v) Sale or offer for sale, as set forth at Sec.  17.21(f) for 
endangered wildlife.
    (2) General exceptions from prohibitions. In regard to this 
species, you may:
    (i) Conduct activities as authorized by a permit under Sec.  17.32.
    (ii) Take, as set forth at Sec.  17.21(c)(2) through (c)(4) for 
endangered wildlife.
    (iii) Take as set forth at Sec.  17.31(b).
    (iv) Possess and engage in other acts with unlawfully taken 
wildlife, as set forth at Sec.  17.21(d)(2) for endangered wildlife.
    (3) Exceptions from prohibitions for specific types of incidental 
take. You may take silverspot butterfly without a permit in wet meadow 
areas where bog violets (Viola nephrophylla/V. sororia var. affinis) 
are growing and immediately adjacent areas with nectar sources while 
carrying out the legally conducted activities set forth in this 
paragraph (h)(3), as long as the activities:
    (i) Are conducted with reasonable care. For the purposes of this 
paragraph, ``reasonable care'' means limiting the impacts to the 
silverspot and bog violet by complying with any and all applicable 
Federal, State, and Tribal regulations for the activity in question; 
using methods and techniques that result in the least harm, injury, or 
death, as feasible; undertaking activities at the least impactful times 
(e.g., conducting activities that might impact habitat during the 
flight season) and locations, as feasible; ensuring the number of 
individuals affected does not impact the existing populations; 
minimizing the potential to introduce invasive plant species; and 
preserving the genetic diversity of populations; and
    (ii) Consist of one or more of the following:
    (A) Grazing:
    (1) Moderate grazing (40 to 55 percent vegetative utilization) in 
late fall to early spring (October 15 to May 31); or
    (2) Light grazing (less than 30 percent vegetative utilization) in 
summer through fall (June 1 to October 14).
    (B) Annual haying or mowing in silverspot habitat in the early 
summer (June 30 or earlier). Blade height must be a minimum of 6 inches 
above the ground, with 8 inches or higher preferred in areas with bog 
violet. In surrounding drier areas, blade height may be lower than 6 
inches where the violet is not present.
    (C) Prescribed burning:
    (1) In the spring (March 1 to April 30); or
    (2) In the fall (October 15 to December 15), if the silverspot 
butterfly has been shown to not be present in a given year through 
adequate monitoring (i.e., at least two surveys at times when 
butterflies are active).
    (D) Brush removal every 4 to 5 years. Brush removal may be 
conducted at any time during the year. Removal can be by mechanical 
means, burning, grazing, or herbicide application if in compliance with 
other excepted activities in this paragraph (h)(3). If mechanical means 
such as a brush hog is used, the blade must be set to 8 inches or 
higher above the ground. If herbicides are used, an appropriate 
systemic herbicide to prevent regrowth must be directly applied to cut 
stems; broadcast spraying is prohibited.
    (E) Spot spraying, hand pulling, or mechanical treatment of noxious 
weeds, which may be conducted at any time during the year. Broadcast 
spraying of noxious weeds is prohibited.
    (F) Replacement of fence poles and wire, and aboveground removal of 
woody vegetation along fence lines, which may be conducted at any time 
during the year. If removal of woody vegetation is done by machine, 
such as a brush hog, the machine blade must be set 8 inches or higher 
above the ground. For permanent removal of woody vegetation, a systemic 
herbicide may be applied directly to the cut stems of woody vegetation; 
broadcast spraying is prohibited.
    (G) Maintenance and operation of existing utility infrastructure 
within and immediately adjacent to silverspot habitat if activities are 
kept within the confines of existing rights-of-way. This exception 
applies to standard activities to repair and maintain existing 
transmission towers, lines, and access roads, and to perform brush 
control, that are conducted as needed at any time during the year. 
Replacement of existing structures and the installation of new 
structures and infrastructure such as access roads are not excepted. 
Noxious weed control and fence maintenance must abide by the exceptions 
for these activities identified in paragraphs (h)(3)(ii)(E) and (F) of 
this section.
    (H) Maintenance of other existing structures within and immediately 
adjacent to silverspot habitat if activities are kept within the 
confines of already disturbed ground.

Martha Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2024-03042 Filed 2-14-24; 8:45 am]
BILLING CODE 4333-15-P